Audi TT 24 User Manual

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Service

Workshop Manual

Audi 100 1991 ➤ , Audi 80 1992 ➤ ,

Audi A1 2011 ➤ , Audi A2 2001 ➤ , Audi A3 1997 ➤ , Audi A3 2004 ➤ , Audi A4 1995 ➤ , Audi A4 2001 ➤ , Audi A4 2008 ➤ , Audi A4 Cabriolet 2003 ➤ , Audi A5 Cabriolet 2009 ➤ , Audi A5 Coupé 2008 ➤ , Audi A5 Sportback 2010 ➤ , Audi A6 1995 ➤ , Audi A6 1998 ➤ , Audi A6 2005 ➤ , Audi A6 2011 ➤ , Audi A7 Sportback 2011 ➤ , Audi A8 1994 ➤ , Audi A8 2003 ➤ , Audi A8 2010 ➤ , Audi Cabriolet 1991 ➤ , Audi Q5 2008 ➤ , Audi Q7 2007 ➤ , Audi R8 2007 ➤ , Audi TT 1999 ➤ , Audi TT 2007 ➤

Air conditioner with refrigerant R134a

Edition 01.2011

Service Department. Technical Information

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Service

List of Workshop Manual Repair GroupsList of Workshop Manual Repair GroupsList of Workshop Manual Repair Groups

Re pa ir G ro up

87 - Air conditioning system

Technical information should always be available to the foremen and mechanics, because their careful and constant adherence to the instructions is essential to ensure vehicle road-worthiness and safety. In addition, the normal basic safety precautions for working on motor vehicles must, as a matter of course, be observed.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Contents

87 - Air conditioning system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1 General information on air conditioning systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Safety precautions for vehicles with a start/stop system . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.4 Other reference material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.5 Basics of air conditioning technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.6 Refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.7 Properties of refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.8 Refrigerant oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.9 How air conditioning works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.10 General work safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.11 Product properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.12 Handling refrigerant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.13 Handling pressure vessels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.14 Safety regulations for working with extraction and charging systems . . . . . . . . . . . . . . . . 13

1.15 Safety measures when working on vehicles with air conditioning and when working with

refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.16 Basics for working on refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.17 Before starting up air conditioning system after fresh charging . . . . . . . . . . . . . . . . . . . . . . 17

2 General information on refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.1 Refrigerant circuit components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.2 Arrangement of the refrigerant circuit components and their influence on the high and low-

pressure ends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.3 Design of refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.4 Quick-release coupling connections in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5 Switches and senders in refrigerant circuit and related connections . . . . . . . . . . . . . . . . . . 31

2.6 Electrical components not installed in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.7 Pressures and temperatures in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

2.8 Test and measurement operations which can be performed with a pressure gauge . . . . 40

2.9 Air conditioner service and recycling units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.10 Repair information for refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3 Laws and regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

3.1 Laws and regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

4 Refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.1 Important repair information for air conditioning systems . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.2 Converting refrigerant circuits from R12 refrigerant to R134a . . . . . . . . . . . . . . . . . . . . . . 48

4.3 Working with the air conditioner service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4.4 Blowing out refrigerant circuit with compressed air and nitrogen . . . . . . . . . . . . . . . . . . . . 60

4.5 Flushing (cleaning) refrigerant circuit with refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . 64

4.6 Determining refrigerant circuit leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

5 Problems with refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

5.1 Possible problems with refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

6 Connecting air conditioner service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

6.1 Connecting air conditioner service station on vehicles with a connection on the low and high-

pressure end of the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

6.2 Connecting air conditioner service station on vehicles with no connection on the low-pressure

end of the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

7 Checking pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

7.1 Checking pressures in refrigerant circuit (with air conditioner service station) with ignition

switched off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

7.2 Checking pressures on vehicles with a restrictor and reservoir (with internally regulated air

conditioner compressor) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Contents i

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

7.3 Checking pressures on vehicles with an expansion valve and receiver (with internally

regulated air conditioner compressor) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

7.4 Checking pressures on vehicles with restrictor, reservoir and air conditioner compressor

regulating valve N280 (with externally regulated air conditioner compressor) . . . . . . . . . . 125

7.5 Checking pressures on vehicles with expansion valve, receiver and air conditioner compressor regulating valve N280 (with externally regulated air conditioner compressor)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

8 Replacing components of refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

8.1 Replacing components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

9 Capacities for refrigerant R134a, refrigerant oil and approved refrigerant oils . . . . . . . . . . 152

9.1 Capacities for refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

9.2 Approved refrigerant oils and refrigerant oil capacities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

10 Test equipment and tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

10.1 List of testers, tools and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

10.2 Tools and materials available from regional sales centre or importer . . . . . . . . . . . . . . . . 201

10.3 Commercially available tools and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

10.4 Improvised tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

ii Contents

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

87 – Air conditioning system

1 General information on air condition‐

ing systems

1.1 General information

♦ Introduction ⇒ page 1

♦ Other reference material ⇒ page 2

♦ Basics of air conditioning technology ⇒ page 3

♦ Refrigerant R134a ⇒ page 5

♦ Properties of refrigerant R134a ⇒ page 6

♦ Refrigerant oil ⇒ page 9

♦ How air conditioning works ⇒ page 10

♦ General work safety ⇒ page 11

♦ Product properties ⇒ page 11

♦ Handling refrigerant ⇒ page 11

♦ Handling pressure vessels ⇒ page 13

♦ Safety regulations for working with extraction and charging

systems ⇒ page 13

♦ Safety measures when working on vehicles with air condition‐

ing and when working with refrigerant R134a ⇒ page 14

♦ Basics for working on refrigerant circuit ⇒ page 15

♦ Before starting up air conditioning system after fresh charging

⇒ page 17

1.2 Introduction

The purpose of this publication is to provide foremen and me‐ chanics with basic knowledge so that they can work in an expert manner.

Note

This requires careful study of the manual, coupled with suitable training on automotive air conditioning systems (with a qualifica‐ tion test if applicable) and the ability to apply the acquired exper‐ tise in practice.

This document is a compact reference work which should be kept at the workplace. It should also be kept available for presentation to the responsible supervisory agency upon request.

1. General information on air conditioning systems 1

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Vehicles with start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

All vehicles

Caution

Non-approved tools or materials (e.g. sealing additives) may damage/impair the system.

Use is only to be made of tools and materials approved by the manufacturer.

Warranty claims will be invalidated by the use of non-approved tools or materials.

1.3 Safety precautions for vehicles with a start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

1.4 Other reference material

♦ Workshop manual for model-specific servicing work ⇒ Heat‐

ing, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Current flow diagrams, Electrical fault finding and Fitting locations

♦ Technical Service Handbook outlining action to be taken to

rectify current problems

♦ Self-study programmes, e.g. ⇒ Self-study programme No.

208 ; Air conditioning systems in motor vehicles

♦ Video programmes for in-dealership training

♦ List of special tools and workshop equipment required for

servicing air conditioning systems ⇒ Workshop equipment catalogue

♦ Service Organisation Handbook Vol. „1“ „Additional equip‐

ment“ ⇒ Audi-ServiceNet, Handbooks

2 Rep. gr.87 - Air conditioning system

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

♦ Air conditioner with refrigerant R12 Workshop Manual (for ve‐

hicles manufactured up to model year 1993; this Workshop Manual is available in hardcopy form only)

1.5 Basics of air conditioning technology

♦ Physical principles ⇒ page 3

♦ Pressure and boiling point ⇒ page 3

♦ Vapour pressure table for refrigerant R134a ⇒ page 4

♦ Properties of refrigerant R134a ⇒ page 6

1.5.1 Physical principles:

The four familiar states of water apply to air conditioning refriger‐ ants as well.

1 - Gas (invisible)

2 - Vapour

3 - Liquid

4 - Solid

When water is heated in a vessel (heat absorption), water vapour can be seen to rise. If the vapour is further heated through heat absorption, the visible vapour turns into invisible gas. The process is reversible. If heat is extracted from gaseous water -A-, it changes first to vapour -B-, then to water and finally to ice.

A - Heat absorption

B - Heat emission

Heat always flows from a warmer to a colder substance

Every substance consists of a mass of moving molecules. The fast moving molecules of a warmer substance give off some of their energy to the cooler and thus slower molecules. As a result, the molecular motion of the warmer substance slows down and that of the colder substance is accelerated. This process contin‐ ues until the molecules of both substances are moving at the same speed. They are then at the same temperature and no fur‐ ther heat exchange takes place.

1.5.2 Pressure and boiling point

The boiling point given in tables for a liquid is always referenced to an atmospheric pressure of 1 bar. If the pressure acting on a fluid changes, its boiling point also changes.

1. General information on air conditioning systems 3

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Note

Pressure may be given in various units: 1 MPa (megapascal) cor‐ responds to 10 bar gauge pressure or 145 psi; 1 bar absolute pressure corresponds to 0 bar gauge pressure, which is roughly equivalent to atmospheric pressure.

For example, the lower the pressure, the lower the temperature at which water boils.

The vapour pressure curves for water and refrigerant R134a show for example that, at constant pressure, reducing the temperature changes vapour to liquid (in the condenser) or that, for instance, reducing pressure causes the refrigerant to change from the liquid to the vapour state (in the evaporator).

Vapour pressure curve for water

A - Liquid

B - Gas

C - Vapour pressure curve for water

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

Vapour pressure curve for refrigerant R134a

A - Liquid

B - Gas

D - Vapour pressure curve for refrigerant R134a

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

1.5.3 Vapour pressure table for refrigerant R134a

The vapour pressure table for every refrigerant is published in literature for refrigeration system engineers. This table makes it possible to determine the vapour pressure acting on the column of liquid in a vessel if the temperature of the vessel is known.

As there is a known characteristic vapour pressure table for every refrigerant, the type of refrigerant can be identified by way of pressure and temperature measurement.

4 Rep. gr.87 - Air conditioning system

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

At absolute pressure, „0 bar“ corresponds to an absolute vac‐ uum. Normal atmospheric pressure corresponds to „1 bar“ absolute pressure. On the scales of most pressure gauges, „0 bar“ corresponds to an absolute pressure of 1 bar (this is in‐ dicated by the value „-1 bar“ below „0“).

♦

Pressure may be given in various units: 1 MPa (megapascal) corresponds to 10 bar gauge pressure or 145 psi; 1 bar ab‐ solute pressure corresponds to 0 bar gauge pressure, which is roughly equivalent to atmospheric pressure.

Temperature in °C Pressure in bar R134a

-45 -0,61

-40 -0,49

-35 -0,34

-30 -0,16

-25 0,06

-20 0,32

-15 0,63

-10 1,00

-5 1,43 0 1,92 5 2,49

10 3,13 15 3,90 20 4,70 25 5,63 30 6,70 35 7,83 40 9,10 45 10,54 50 12,11 55 13,83 60 15,72 65 17,79 70 20,05 75 22,52 80 25,21 85 28,14 90 31,34

1.6 Refrigerant R134a

Vehicle air conditioning systems make use of the vaporisation and condensation process. Use is made of a substance with a low boiling point, referred to as refrigerant.

The refrigerant used is tetrafluoroethane R134a, which boils at

-26.5°C at a vapour pressure of „1 bar“.

♦ Physical data of refrigerant R134a ⇒ page 6

♦ Critical point ⇒ page 6

1. General information on air conditioning systems 5

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

♦ Environmental aspects of refrigerant R134a ⇒ page 6

1.6.1 Physical data of refrigerant R134a

Chemical formula CH2F–CF3 or CF3–CH2F Chemical designation Tetrafluoroethane Boiling point at 1 bar -26.5 °C Solidification point -101.6 °C Critical temperature 100.6 °C Critical pressure 40.56 bar (absolute)

1.6.2 Critical point

The critical point (critical temperature and critical pressure) is that above which there is no longer a boundary between liquid and gas.

A substance above its critical point is always in the gaseous state.

At temperatures below the critical point, all types of refrigerant in pressure vessels exhibit both a liquid and a gas phase, i.e. there is a layer of gas above the liquid.

As long as both liquid and gas are present in the vessel, the pres‐ sure is governed by ambient temperature ⇒ page 4 „Vapour pressure table“.

Note

Different types of refrigerant are never to be mixed. Exclusive use is to be made of the refrigerant specified for the respective air conditioning system.

1.6.3 Environmental aspects of refrigerant R134a

♦ R134a is a fluorocarbon and contains no chlorine.

♦ R134a has a shorter atmospheric lifespan than refrigerant

R12.

♦ R134a does not damage the ozone layer, the ozone depletion

potential is zero.

♦ The global warming potential (GWP) of R134a is 1300 (the

GWP of carbon dioxide = 1).

♦ The global warming effect of R134a is „10“ times less than that

of refrigerant R12.

1.7 Properties of refrigerant R134a

♦ Trade names and designations ⇒ page 7

♦ Colour ⇒ page 7

♦ Vapour pressure ⇒ page 7

♦ Physical properties of R134a ⇒ page 7

♦ Effects on metal ⇒ page 7

♦ Critical temperature / critical pressure ⇒ page 7

♦ Water content ⇒ page 8

♦ Combustibility ⇒ page 8

♦ Charge factor ⇒ page 8

6 Rep. gr.87 - Air conditioning system

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

♦ Detecting leaks ⇒ page 8

1.7.1 Trade names and designations

The refrigerant R134a is currently available under the following trade names:

♦ H-FKW 134a

♦ SUVA 134a

♦ KLEA 134a

Note

♦

Different trade names may be used in other countries.

♦

Of the wide range of refrigerants available, this is the only one which may be used for vehicles. The names Frigen and Freon are trade names. They also apply to refrigerants which are not to be used in vehicles.

1.7.2 Colour

Like water, refrigerants are colourless in both vapour and liquid form. Gas is invisible. Only the boundary layer between gas and liquid is visible (liquid level in indicator tube of charging cylinder or bubbles in sight glass). Liquid refrigerant R134a may have a coloured (milky) appearance in a sight glass. This cloudiness is caused by partially dissolved refrigerant oil and does not indicate a fault.

1.7.3 Vapour pressure

In a partially filled, closed vessel, the quantity of refrigerant evap‐ orating from the surface equals the quantity returning to the liquid state as vapour particles condense. This state of equilibrium oc‐ curs under the influence of pressure and is often called vapour pressure. Vapour pressure is a function of temperature

⇒ page 4 „Vapour pressure table“.

1.7.4 Physical properties of R134a

As the vapour pressure curves of R134a and other refrigerants are often very similar, unequivocal identification cannot be made simply on the basis of pressure.

When using R134a, the air conditioner compressor is lubricated by means of special synthetic refrigerant oils, e.g. PAG oils (pol‐ yalkylene glycol oils).

1.7.5 Effects on metal

In its pure state, refrigerant R134a is chemically stable and does not corrode iron or aluminium.

However, contamination of the refrigerant, e.g. with chlorine com‐ pounds, leads to the corrosion of certain metals and plastics. This can result in blockage, leaks or deposits at the air conditioner compressor piston.

1.7.6 Critical temperature / critical pressure

The refrigerant R134a remains chemically stable up to a gas pressure of 39.5 bar (corresponding to a temperature of 101 °C). Above this temperature, the refrigerant decomposes (refer to "Combustibility").

1. General information on air conditioning systems 7

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1.7.7 Water content

Only very small amounts of water are soluble in liquid refrigerant. On the other hand, refrigerant vapour and water vapour mix in any ratio.

Any water in the refrigerant circuit will be entrained in droplet form once the dryer in the receiver or reservoir has absorbed as little as approx. 7 g of water. This water flows as far as the expansion valve nozzle or the restrictor and turns to ice. The air conditioner no longer provides any cooling effect.

Water destroys the air conditioner because at high pressures and temperatures it combines with other impurities to form acids.

1.7.8 Combustibility

Refrigerant is non-flammable. In fact it has a fire-inhibiting or fireextinguishing effect. Refrigerant decomposes when exposed to flames or red-hot surfaces. UV light (occurring for example during electric welding) also causes refrigerant decomposition. Products of such decomposition are poisonous and must not be inhaled. However, these chemicals irritate the mucous membranes, giving adequate warning of their presence.

1.7.9 Charge factor

A vessel must have space for vapour as well as liquid. As the temperature rises, the liquid expands. The vapour-filled space becomes smaller. At a certain point, there will only be liquid in the vessel. Beyond this, even a slight increase in temperature causes great pressure to build up in the vessel as the liquid attempts to continue expanding despite the absence of the necessary space. The resultant force is sufficient to rupture the vessel. To stop ves‐ sels being overfilled, regulations governing the storage of com‐ pressed gases specify the number of kilograms of refrigerant with which a vessel may be filled per litre of internal vessel volume. The product of multiplying this charge factor by the internal vol‐ ume of the vessel is the permissible capacity. The figure for the refrigerant used in motor vehicles is 1.15 kg/litre.

1.7.10 Detecting leaks

External damage, for example, can cause a leak in the refrigerant circuit. The small quantity of refrigerant escaping from minor leaks can be detected for example using an electronic leak detector or by introducing a leak detection additive into the refrigerant circuit. Electronic leak detectors are capable of registering leaks with re‐ frigerant losses of less than 5 g per year.

Note

Use must be made for the various refrigerants of leak detectors designed for the composition of the refrigerant concerned. For example, a leak detector for R12 refrigerant is not appropriate for R134a, as R134a refrigerant has no chlorine atoms and the leak detector therefore does not respond.

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1.8 Refrigerant oil

Caution

♦ For handling of refrigerant oil, refer to ⇒ Audi-ServiceNet,

HSO Environmental Protection (or ⇒ Volkswagen-Serv‐ iceNet, Handbooks, Service Handbook; Environmental Protection; Immission Protection ).

Refrigerant oil mixes with the refrigerant (about 20 - 40 %, de‐ pending on compressor type and amount of refrigerant) and circulates constantly in the system, lubricating the moving parts.

Special synthetic refrigerant oils, e.g. polyalkylene glycol (PAG) oil, are used in conjunction with R134a air conditioning systems. This is necessary as mineral oil, for example, does not mix with R134a. In addition, the materials of the R134a air conditioning system could be corroded as a result of mixture flowing through the refrigerant circuit under pressure at high temperatures or breakdown of the lubricating film in the air conditioner compres‐ sor. The use of non-approved oils can lead to the failure of the air conditioning system; exclusive use is therefore to be made of au‐ thorised oils.

⇒ Electronic parts catalogue

Type of oil for R134a in motor vehicles: PAG. (polyalkylene glycol)

Note

♦

Do not store refrigerant oils in open containers as they are extremely hygroscopic (water-absorbing).

♦

Always keep oil container sealed.

♦

Do not re-use old refrigerant oil. It must be disposed of as used oil of unknown origin ⇒ Audi-ServiceNet, HSO Environmental Protection (or ⇒ Volkswagen-ServiceNet, Handbooks, Serv‐ ice Handbook; Environmental Protection; Immission Protec‐ tion ).

♦

Ester-based oils are only intended for use with large systems (not for motor vehicle air conditioners).

♦ Properties of refrigerant oil ⇒ page 9

1.8.1 Properties of refrigerant oil

The most important properties are a high degree of solubility with refrigerant, good lubricity, absence of acid and minimal water content. It is therefore only permissible to use certain specified oils. For a list of approved refrigerant oils and capacities, refer to

⇒ page 174 .

PAG oils, which are appropriate for refrigerant R134a, are highly hygroscopic and do not mix with other oils. Opened containers should therefore be closed again immediately to prevent ingress of moisture. Moisture and acids promote the ageing of refrigerant oil, causing it to become dark, viscous and corrosive towards metals.

1. General information on air conditioning systems 9

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Note

♦

On account of its chemical properties, the refrigerant oil is not to be disposed of together with engine or gear oil. Refrigerant oil must be disposed of as used oil of unknown origin ⇒ AudiServiceNet, HSO Environmental Protection (or ⇒ Volkswa‐ gen-ServiceNet, Handbooks, Service Handbook; Environ‐ mental Protection; Immission Protection ).

♦

Only oil approved for the air conditioner compressor is to be used for refrigerant circuits containing refrigerant R134a ⇒ Electronic parts catalogue and capacities ⇒ page 174 .

1.9 How air conditioning works

The temperature in the passenger compartment depends on the amount of heat radiated through the windows and conducted by the metal parts of the body. In hot weather some of the heat must be pumped off to achieve a more comfortable temperature for the occupants.

As heat spreads into cooler areas, the passenger compartment is fitted with a unit for generating low temperatures in which re‐ frigerant is constantly evaporated. The heat required for this is extracted from the air flowing through the evaporator.

After absorbing heat, the refrigerant is pumped off through the air conditioner compressor. The work of compression of the air con‐ ditioner compressor increases the heat content and temperature of the refrigerant. Its temperature is now substantially higher than that of the surrounding air.

The hot refrigerant flows with its heat content to the condenser, where the refrigerant dissipates its heat to the surrounding air via the condenser due to the temperature gradient between the re‐ frigerant and the surrounding air.

The refrigerant thus acts as a heat transfer medium. As it is reused, the refrigerant is returned to the evaporator.

For this reason all air conditioning systems are based on the re‐ frigerant circulation principle. There are however differences in the composition of the units.

♦ Comfort ⇒ page 10

♦ Environmental aspects ⇒ page 11

1.9.1 Comfort

A basic requirement for concentrated and safe driving is a feeling of comfort in the passenger compartment. Especially when it is hot and humid, comfort can only be attained through the use of air conditioning. Comfort can of course also be enhanced by opening windows/the sun roof or increasing the air output. Such a course of action is however associated with certain drawbacks for the occupants of the vehicle, e.g. more noise, draughts, ex‐ haust fumes and unfiltered pollen (unpleasant for allergy suffer‐ ers).

Climate control together with a good heating and ventilation sys‐ tem concept can create a sense of wellbeing and comfort by regulating the temperature, humidity and air circulation in the passenger compartment to suit ambient conditions, with the ve‐ hicle both stationary and moving.

Other important advantages of air conditioning are:

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♦ Purification of the air supplied to the passenger compartment

(dust and pollen, for example, are washed out by the moist fins of the evaporator and removed with the condensate).

♦ Temperatures in a mid-size car (example: after short travelling

time, ambient temperature 30 °C in the shade and vehicle ex‐ posed to sunlight).

With air conditioning Without air condi‐

tioning

At head height 23 °C 42 °C At chest level 24 °C 40 °C In footwell 30 °C 35 °C

1.9.2 Environmental aspects

As of around 1992, the air conditioning systems of newly manu‐ factured cars have been successively changed to refrigerant R134a. This refrigerant contains no chlorine and therefore does not deplete the ozone layer.

Until about 1992, the air conditioning systems were equipped with refrigerant R12. Due to its chlorine atoms, this CFC had a high ozone depletion potential as well as potential for intensifying the greenhouse effect.

Conversion programmes are available for old existing systems filled with the ozone-depleting substance R12 ⇒ Workshop Man‐ ual for air conditioners with refrigerant R12 (this Workshop Man‐ ual is available in hardcopy form only).

For environmental protection reasons, refrigerants must not be released into the atmosphere ⇒ page 43 (laws and regulations).

1.10 General work safety

♦ As per VBG 20, German industrial liability insurance associa‐

tion (other regulations may apply in other countries)

♦ Heed the workplace-specific instructions ⇒ Audi-ServiceNet,

HSO Environmental Protection , which are to be displayed at refrigerant workplaces.

1.11 Product properties

Refrigerants used in motor vehicle air conditioning systems be‐ long to the new generation of refrigerants based on chlorine-free, partially fluorinated hydrocarbons (H-FKW, R134a; other names may be used in other countries).

With regard to their physical properties, these are refrigerants which have been liquified under pressure. They are subject to the regulations governing pressure vessels and use is only to be made of approved and appropriately marked containers.

Compliance with specific conditions is required to ensure safe and proper use.

1.12 Handling refrigerant

If refrigerant vessels are opened, the contents may escape in liq‐ uid or vapour form. The higher the pressure in the vessel, the more vigorous the process.

How high the pressure is depends on two factors:

• The type of refrigerant in the vessel. „Rule: The lower the boil‐ ing point, the higher the pressure.“

• The temperature „Rule: The higher the temperature, the high‐ er the pressure.“

1. General information on air conditioning systems 11

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WARNING

♦ There is a risk of icing-up.

♦ The refrigerant may emerge in liquid or vapour form.

♦ Do not open vessels containing refrigerant.

Wear safety goggles

Put on safety goggles to prevent refrigerant getting into the eyes, as this could cause severe injury through frostbite.

Wear protective gloves and an apron

Greases and oils dissolve readily in refrigerants. They would therefore destroy the protective layer of grease if allowed to come into contact with the skin. Degreased skin is however sensitive to the cold and germs.

Do not allow liquid refrigerant to come into contact with the skin

The refrigerant draws heat for evaporation from the surrounding area - even if this is the skin. This may give rise to extremely low temperatures and result in local frostbite (boiling point of R134a:

-26.5 °C at ambient pressure).

Do not inhale refrigerant vapours

If highly concentrated refrigerant vapour escapes, it mixes with the surrounding air and displaces the oxygen necessary for breathing.

Smoking is absolutely prohibited

A burning cigarette can cause refrigerant to decompose. The re‐ sultant substances are toxic and must not be inhaled.

Welding and soldering on refrigeration systems

Before performing welding or soldering work on vehicles in the vicinity of air conditioning system components, extract refrigerant and remove remnants by blowing out with nitrogen.

The products of decomposition of the refrigerant arising from the effect of heat are not only toxic, but also highly corrosive and can therefore damage pipes and sections of the system. The principal substance is hydrogen fluoride.

Pungent odour

A pungent odour indicates that the products of decomposition mentioned above are already present. Avoid inhaling these sub‐ stances under all circumstances, as otherwise the airways, lungs and other organs could be damaged.

First aid

• Following contact with eyes or mucous membranes, immedi‐ ately rinse with copious amounts of running water and consult an eye specialist.

• Following contact with the skin, immediately remove clothing affected and rinse skin with copious amounts of water.

• Following inhalation of highly concentrated refrigerant va‐ pours, the person concerned is to be taken immediately into the open air. Call a doctor. Administer oxygen in the event of breathing difficulties. If the person affected is having great dif‐ ficulty breathing or is not breathing at all, tilt back the head and administer artificial respiration.

♦ Handling pressure vessels ⇒ page 13

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1.13 Handling pressure vessels

Secure vessels to prevent them falling over.

Secure upright cylinders to stop them falling over and cylinders lying flat to stop them rolling away.

Vessels are never to be thrown.

If dropped, the vessels could be so severely deformed that they rupture. The refrigerant evaporates immediately, liberating con‐ siderable force. Flying fragments of cylinders can cause severe injuries.

To protect the cylinder valves, cylinders are only to be transported with the protective cap screwed on.

Cylinder valves may break off if not properly transported.

Never store in the vicinity of radiators,

as high temperatures may occur in these areas. High tempera‐ tures are also accompanied by high pressures and the maximum permissible vessel pressure may be exceeded.

Never heat to above 50 °C

To avoid possible risk, pressure vessel regulations specify that vessels are not to be heated to in excess of 50 °C.

Do not heat in an uncontrolled manner

Do not heat with a naked flame under any circumstances. Local‐ ised overheating can cause structural changes in the vessel material, which then reduce its ability to withstand pressure. There is also a danger of the refrigerant decomposing due to lo‐ calised overheating.

Seal empty vessels

Empty refrigerant containers must always be closed to prevent the penetration of moisture. Moisture causes steel containers to rust. Rust weakens the container walls. In addition, rust particles which ingress into refrigeration systems from containers cause malfunctions.

1.14 Safety regulations for working with ex‐ traction and charging systems

• Before connecting the charging system to the air conditioning

system, ensure that the shut-off valves are closed.

• Before disconnecting the charging system from the air condi‐

tioning system, ensure that the process has been completed so that no refrigerant can escape into the atmosphere.

• Once the purified refrigerant from the charging system has

been filled into an external compressed-gas cylinder, close the hand shut-off valves at the cylinder and charging system.

• Do not expose the charging system to moisture or use it in a

wet environment.

• Before performing service work on the charging system, dis‐

connect the power supply.

• To reduce the danger of fire, avoid using an extension cable.

If the use of an extension cable is unavoidable, the minimum cross-section should be 2.5 mm2.

• In case of fire, remove the external cylinder.

• Entrained oil from the air conditioning system drawn off by the

suction unit into the measurement vessel supplied is subse‐ quently to be transferred to a sealable container, as it contains

1. General information on air conditioning systems 13

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a small quantity of refrigerant which must not be released into the environment.

• Following shutdown, the air conditioner service station is to be secured to stop it rolling away.

1.15 Safety measures when working on ve‐

hicles with air conditioning and when working with refrigerant R134a

Vehicles with start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

All vehicles

WARNING

♦ It is advisable to always keep an eye bath to hand.

♦ Should liquid refrigerant come into contact with the eyes,

rinse them thoroughly with water for about 15 minutes. Then administer eye drops and consult a doctor immedi‐ ately even if no pain is felt.

♦ The doctor must be informed that the frostbite was caused

by refrigerant R134a. Should refrigerant come into contact with other parts of the body despite compliance with the safety regulations, these must likewise be rinsed immedi‐ ately for approximately 15 minutes with cold water.

♦ Work may only be performed on the refrigerant circuit of

an air conditioning system in well ventilated areas. Work‐ shop extraction systems are to be switched on.

♦ Refrigerant must not be stored in low-level areas (e.g. cel‐

lars) and their exits or light wells.

• Welding, brazing and soldering operations are not to be per‐ formed on air conditioner components when filled. This also applies to vehicle welding and soldering work if there is a dan‐ ger of air conditioner components becoming hot. When per‐ forming paintwork repairs, the temperature in the drying booth or preheating zone must not exceed 80 °C.

Reason:

Exposure to heat gives rise to considerable pressure in the sys‐ tem, which could cause the pressure relief valve to open.

Remedy:

– Discharge refrigerant circuit with air conditioner service sta‐

tion.

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Note

Damaged or leaking components of the air conditioning system are not to be repaired by welding or soldering. They must always be replaced.

Refrigerant vessels (e.g. charging cylinders of air conditioner service station) must never be subjected to excessive heat or ex‐ posed to direct sunlight.

Remedy:

– Vessels must never be completely filled with liquid refrigerant.

Without sufficient room for expansion (gas cushion), vessels will rupture with devastating effect in the event of an increase in temperature ⇒ page 6 .

Refrigerant should never be poured into systems or vessels con‐ taining any air.

Remedy:

– Evacuate systems and containers before charging with refrig‐

erant.

1.16 Basics for working on refrigerant circuit

Vehicles with start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

All vehicles

♦ General ⇒ page 15

♦ Cleaning refrigerant circuit ⇒ page 16 .

♦ Additionally for vehicles with air conditioner compressor with

no magnetic clutch (with air conditioner compressor regulating valve -N280- ) ⇒ page 16

♦ O-rings ⇒ page 16

1.16.1 General

• Heed the workplace-specific instructions ⇒ Audi-ServiceNet, HSO Environmental Protection .

• Ensure absolute cleanliness when working.

• Wear safety goggles and gloves when working with refrigerant and nitrogen.

• Workshop extraction systems are to be switched on.

• Always use air conditioner service station to discharge refrig‐ erant circuit, then unfasten screw connections and replace defective components.

1. General information on air conditioning systems 15

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• Use caps to seal off opened assemblies and hoses to prevent the ingress of moisture and dirt.

• Make exclusive use of tools and materials intended for refrig‐ erant R134a.

• Seal opened refrigerant oil containers to protect against mois‐ ture.

Note

♦

After completing service work, screw sealing caps (with seals) onto all connections with valves and service connections.

♦

Before starting up the air conditioning system, heed the vehi‐ cle-specific capacities ⇒ page 152 .

♦

Do not top up the refrigerant in the circuit; discharge the ex‐ isting refrigerant and re-charge the system.

1.16.2 Cleaning refrigerant circuit

Flush the refrigerant circuit with refrigerant R134a ⇒ page 64 (or blow out with compressed air and nitrogen ⇒ page 60 ) in the following cases:

– If moisture or dirt has ingressed into the refrigerant circuit (e.g.

following an accident).

– If the refrigerant oil is dark and viscous.

– If there is too much refrigerant oil in the refrigerant circuit after

compressor replacement.

– If the air conditioner compressor has to be replaced on ac‐

count of „internal“ damage (e.g. noise or no output).

Note

When flushing components with compressed air and nitrogen, al‐ ways extract the gas mixture escaping from the components with suitable extraction units (workshop extraction system).

1.16.3 Additionally for vehicles with air condi‐

tioner compressor with no magnetic clutch (with air conditioner compressor regulating valve -N280- only)

• The engine is only to be started following complete assembly of the refrigerant circuit (constant air conditioner compressor operation).

• If the engine has to be operated with the refrigerant circuit empty, only do so for as long as absolutely essential and avoid high engine speeds.

1.16.4 O-rings

♦ Make exclusive use of seals which are resistant to refrigerant

R134a and the related refrigerant oils. Colour coding of the Oring seals is no longer employed. Black and coloured O-rings are used.

♦ Pay attention to the correct inside diameter of the seals used

⇒ Electronic parts catalogue , ⇒ Heating, air conditioning; Rep. gr. 87 and / or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual).

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♦ Seals are only to be used once.

♦ Before fitting, moisten seals slightly with refrigerant oil (PAG

oil).

1.17 Before starting up air conditioning sys‐ tem after fresh charging

– Give the air conditioner compressor approx. 10 turns by hand

by way of the magnetic clutch plate or the pulley.

– Start the engine with the air conditioning system switched off

( air conditioning system magnetic clutch -N25- and air condi‐ tioner compressor regulating valve -N280- are not actuated).

– Switch on the air conditioner compressor once the idling speed

has stabilised and run it for at least 10 minutes at idle in the maximum cooling output setting.

1. General information on air conditioning systems 17

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2 General information on refrigerant

circuit

Vehicles with start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

All vehicles

♦ Refrigerant circuit components ⇒ page 18

♦ Arrangement of the refrigerant circuit components and their

influence on the high and low-pressure ends ⇒ page 19

♦ Design of refrigerant circuit ⇒ page 28

♦ Quick-release coupling connections in refrigerant circuit

⇒ page 29

♦ Switches and senders in refrigerant circuit and related con‐

nections ⇒ page 31

♦ Electrical components not fitted in the refrigerant circuit

⇒ page 35 .

♦ Pressures and temperatures in refrigerant circuit

⇒ page 36

♦ Test and measurement operations which can be performed

with a pressure gauge ⇒ page 40

♦ Air conditioner service and recycling units ⇒ page 41

♦ Repair information for refrigerant circuit ⇒ page 42

2.1 Refrigerant circuit components

• All components of the refrigerant circuit submitted for quality observation are always to be sealed (use the original sealing caps of the replacement part).

• Replace damaged or leaking components of the refrigerant circuit ⇒ page 143 .

Note

The following replacement parts (air conditioner compressor, res‐ ervoir, evaporator and condenser) have so far been filled with nitrogen gas. This charge is being gradually discontinued. Con‐ sequently, no or only very slight pressure equalisation is percep‐ tible on unscrewing the sealing plugs from the replacement part.

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2.2 Arrangement of the refrigerant circuit components and their influence on the high and low-pressure ends

High-pressure end: Condenser, receiver and restrictor or expan‐ sion valve to separate the high and low-pressure liquid ends.

High pressure results from the restrictor or expansion valve form‐ ing a constriction and causing the refrigerant to accumulate, thus leading to an increase in pressure and temperature.

Excess pressure occurs if too much refrigerant or refrigerant oil is used, the condenser is contaminated, the radiator fan is defec‐ tive, the system is blocked or in the event of moisture in the refrigerant circuit (icing-up of restrictor or expansion valve).

Low-pressure end: Evaporator, evaporator temperature sensor and air conditioner compressor to separate the high and lowpressure gas ends.

A drop in system pressure can be caused by a loss of refrigerant, the restrictor or expansion valve (constrictions), a defective air conditioner compressor or an iced-up evaporator.

♦ Air conditioner compressor ⇒ page 20

♦ Condenser ⇒ page 21

♦ Evaporator ⇒ page 22

♦ Reservoir ⇒ page 22

♦ Restrictor ⇒ page 23

♦ Receiver ⇒ page 24

♦ Expansion valve ⇒ page 25

♦ Refrigerant line with internal heat exchanger ⇒ page 25

♦ Refrigerant line quick-release coupling connections

⇒ page 26

♦ O-rings ⇒ page 27

♦ Pipes and hoses of refrigerant circuit ⇒ page 27

♦ Pressure relief valve ⇒ page 28

2. General information on refrigerant circuit 19

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2.2.1 Air conditioner compressor

The air conditioner compressor is driven by the engine via a poly V-belt or a drive shaft.

Air conditioner compressor with magnetic clutch:

♦ An electromagnetic clutch -A- attached to the air conditioner

compressor provides the power link between the pulley -Band the compressor crankshaft when the air conditioning sys‐ tem is switched on.

♦ An overload safeguard attached to the clutch plate or fitted in

the solenoid of the air conditioner compressor is triggered if the air conditioner compressor is not running smoothly in order to protect the belt drive against overload.

Air conditioner compressor with no magnetic clutch:

♦ An overload safeguard attached to the pulley -B- or fitted in

the drive unit of the air conditioner compressor is triggered if the air conditioner compressor is not running smoothly in order to protect the belt drive against overload.

All air conditioner compressors

The air conditioner compressor draws in refrigerant gas from the evaporator, compresses it and conveys it to the condenser.

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Note

♦

The air conditioner compressor contains refrigerant oil which mixes with refrigerant R134a at all temperatures.

♦

The rating plate indicates the refrigerant for which the air con‐ ditioner compressor is designed. A valve regulates the pres‐ sure on the low-pressure end within the specified range (control characteristic).

♦

At present, actuation is effected externally by way of a regu‐ lating valve -C- on air conditioner compressors with or without magnetic clutch.

♦

On air conditioner compressors with no magnetic clutch, the engine is only to be started following complete assembly of the refrigerant circuit.

♦

To prevent air conditioner compressor damage if the refriger‐ ant circuit is empty, the magnetic clutch is deactivated and the air conditioner compressor regulating valve -N280- no longer actuated (air conditioner compressor idles with engine).

♦

If the refrigerant circuit is empty, an air conditioner compressor with no air conditioning system magnetic clutch -N25- (with air conditioner compressor regulating valve -N280- ) is switched to internal lubrication by way of a valve.

♦

Depending on the version of the air conditioner compressor, the high-pressure end of the air conditioner compressor may be fitted with a valve to prevent the backflow of liquid refriger‐ ant into the compressor after switching off the air conditioning system. If an air conditioner compressor with this valve is fitted on a vehicle with a refrigerant circuit with an expansion valve, a relatively long period may elapse before the pressure on the high-pressure end decreases (the expansion valve is cold and the pressure on the low-pressure end increases rapidly after switch-off, the expansion valve closes and the refrigerant can only flow slowly to the low-pressure end). If the air conditioner compressor is switched on, the pressure on the low-pressure end decreases, the expansion valve opens and the refrigerant can flow to the low-pressure end.

♦

In the case of air conditioner compressors with an electro‐ magnetic clutch -A- and a regulating valve -C-, the electro‐ magnetic clutch -A- is usually only actuated when the regulating valve -C- is actuated as well ⇒ Air conditioning; Rep. gr. 87 .

2.2.2 Condenser

The condenser transfers heat from the compressed refrigerant gas to the surrounding air.

In this process, the refrigerant gas condenses to form liquid.

Depending on the design of the refrigerant circuit, the receiver may be attached to the condenser or installed in (integrated into) the condenser ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

Note

2. General information on refrigerant circuit 21

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

2.2.3 Evaporator

The liquid refrigerant evaporates in the tubes of the evaporator. The required heat is extracted from the air flowing past the evap‐ orator ribs. The air cools down. The refrigerant evaporates and is drawn in by the air conditioner compressor together with the heat absorbed.

A restrictor or an expansion valve supplies a defined quantity of refrigerant to the evaporator. In systems with an expansion valve the flow rate is regulated such that only gaseous refrigerant emerges at the evaporator outlet.

2.2.4 Reservoir

To ensure that the air conditioner compressor draws in only gas‐ eous refrigerant, the reservoir collects the mixture of vapour and gas coming from the evaporator. The vapour becomes gaseous refrigerant.

Refrigerant oil entrained in the circuit does not remain in the res‐ ervoir as an oil extraction hole is provided.

Any moisture ingressing into the refrigerant circuit during assem‐ bly is trapped by a filter (desiccant bag) in the reservoir.

Gaseous refrigerant with oil is drawn in by the air conditioner compressor.

Note

♦

Replace the reservoir if the refrigerant circuit has been open for a lengthy period and moisture has ingressed or if replace‐ ment is stipulated on the basis of a specific complaint

⇒ page 143 .

♦

Do not remove the sealing plugs -A- and -B- until immediately prior to installation.

♦

If the reservoir is not sealed, the desiccant bag soon becomes saturated with moisture and thus unusable.

♦

When installing, observe arrow indicating direction of flow if applicable.

22 Rep. gr.87 - Air conditioning system

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2.2.5 Restrictor

The restrictor creates a constriction. This constriction restricts the flow, thus separating the refrigerant circuit into a high and lowpressure end. Upstream of the restrictor, the refrigerant is warm due to the high pressure. Downstream of the restrictor, the refrig‐ erant is cold due to the low pressure. Upstream of the narrow point is a strainer to catch dirt and downstream of the narrow point is a strainer to atomise the refrigerant before it enters the evaporator.

Note

♦

Arrow -A- on restrictor faces evaporator.

♦

Always replace after opening the circuit.

♦

Different versions exist; heed the applicable notes in the var‐ ious service information booklets ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

2. General information on refrigerant circuit 23

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2.2.6 Receiver

The receiver collects the droplets of liquid and conveys them in a continuous flow to the expansion valve. Any moisture ingressing into the refrigerant circuit during assembly is collected by a dryer in the receiver.

Note

♦

Replace the receiver if the refrigerant circuit has been open for a lengthy period and moisture has ingressed or if replace‐ ment is stipulated on the basis of a specific complaint

⇒ page 143 .

♦

Do not remove the sealing plugs until immediately prior to in‐ stallation.

♦

If the receiver is not sealed, the desiccant bag soon becomes saturated with moisture and thus unusable.

♦

When installing, observe arrow indicating direction of flow if applicable.

♦

Depending on the design of the refrigerant circuit, the receiver may also be attached to the condenser or installed in (inte‐ grated into) the condenser ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

♦

The procedure for dealing with problems differs depending on the version of the receiver / dryer cartridge. If, for example, the receiver is attached to the condenser, it can be replaced to‐ gether with the dryer cartridge. If, for example, the receiver is integrated into the condenser, it is usually possible to replace the dryer cartridge and any additional filter element separately. If the receiver is integrated into the condenser and it is not possible to replace the receiver/dryer cartridge separately, it may be necessary to replace the entire condenser ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

♦

Depending on the design of the refrigerant circuit, the desic‐ cant bag (dryer cartridge) may also be installed in the con‐ denser ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

24 Rep. gr.87 - Air conditioning system

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Air conditioner with refrigerant R134a - Edition 01.2011

2.2.7 Expansion valve

The expansion valve atomises the refrigerant flowing in and con‐ trols the flow rate in line with the quantity of heat transferred such that it does not become gaseous before reaching the evaporator outlet.

Note

♦

Pay attention to the correct part number on replacing the ex‐ pansion valve. ⇒ Electronic parts catalogue

♦

Different characteristic curves matched to the appropriate cir‐ cuit ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air condi‐ tioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

♦

Depending on the version of the air conditioner compressor, the high-pressure end of the air conditioner compressor may be fitted with a valve to prevent the backflow of liquid refriger‐ ant into the compressor after switching off the air conditioning system. If an air conditioner compressor with this valve is fitted on a vehicle with a refrigerant circuit with an expansion valve, a relatively long period may elapse before the pressure on the high-pressure end decreases (the expansion valve is cold and the pressure on the low-pressure end increases rapidly after switch-off, the expansion valve closes and the refrigerant can only flow slowly to the low-pressure end). If the air conditioner compressor is switched on, the pressure on the low-pressure end decreases, the expansion valve opens and the refrigerant can flow to the low-pressure end.

2.2.8 Refrigerant line with internal heat ex‐ changer

In this refrigerant line, the hot liquid refrigerant flowing on the highpressure end supplies energy to the cold refrigerant gas or vapour flowing on the low-pressure end, thus enhancing the efficiency of the air conditioner.

Note

This illustration shows a refrigerant line with an internal heat ex‐ changer as fitted for example on the Audi A4 2008 > and the Audi A5 Coupé 2008 > ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

A - Refrigerant line with internal heat exchanger

B - Channels in the refrigerant line in which the hot liquid refrig‐ erant flows to the evaporator (high-pressure end of the refrigerant circuit).

C - Channel in the refrigerant line in which the cold refrigerant gas or vapour flows to the air conditioner compressor (low-pressure end of the refrigerant circuit).

2. General information on refrigerant circuit 25

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

2.2.9 Refrigerant line quick-release coupling connections

WARNING

The quick-release couplings are only to be released and un‐ fastened after draining the refrigerant circuit.

Note

♦

This illustration shows the quick-release couplings with a re‐ frigerant line with an internal heat exchanger as fitted for example on the Audi A4 2008 > and the Audi A5 Coupé 2008 > ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦

Removal of the refrigerant line -D- involves opening the re‐ taining ring -A- with the air conditioner line release tool T40149/- for example ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual).

♦

Following removal of the applicable refrigerant line, the quickrelease couplings -B- and -G- are to be replaced together with the corresponding support ring -E- or -H- and the correspond‐ ing O-ring -F- or -J- ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual) and ⇒ Electronic parts catalogue .

A - Retaining ring (in quick-release coupling connection on highpressure end)

B - Quick-release coupling connection with retaining ring „highpressure end“

C - Refrigerant line with an internal heat exchanger

D - Refrigerant line „high-pressure end“

E - Support ring „high-pressure end“

F - O-ring „high-pressure end“

G - Quick-release coupling connection with retaining ring „lowpressure end“

H - Support ring „low-pressure end“

J - O-ring „low-pressure end“

26 Rep. gr.87 - Air conditioning system

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Note

♦

There are different versions -A- and -D- of the quick-release couplings. With both versions of these quick-release cou‐ plings, the refrigerant lines -C- can be released in the identical manner using the air conditioner line release tool -T40149/1for example and removed.

♦

With the quick-release coupling -A- fitted at the start of pro‐ duction, the pins -B- become visible after fitting the refrigerant line -C- if the locked refrigerant line -C- is pulled in arrow di‐ rection.

♦

With the quick-release coupling -A- to be gradually introduced as of Model Year 2010, the refrigerant line -C- is fitted in the same manner as for the quick-release coupling -A-. If, with this version, the refrigerant line -C- is pulled in arrow direction fol‐ lowing assembly, the snap ring -E- emerges from the quickrelease coupling -D- to show that the retaining ring -F- and the refrigerant line -C- are fully locked. The snap ring -E- is then to be detached from the refrigerant line -C-.

2.2.10 O-rings

These rings seal the joints between the individual components of the refrigerant circuit.

Only O-rings resistant to R134a refrigerant and the related refrig‐ erant oils are to be used. This is guaranteed by genuine replace‐ ment parts.

O-rings:

– Only ever use once.

– Pay attention to correct diameters -a- and -b-.

– Moisten with refrigerant oil before fitting ⇒ Heating, air condi‐

tioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual) and ⇒ Electronic parts catalogue .

Note

The colour coding of O-rings for the R134a refrigerant circuits has been discontinued. Use is made of black and coloured O-rings ⇒ Electronic parts catalogue and ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific work‐ shop manual).

2.2.11 Pipes and hoses of refrigerant circuit

The mixture of refrigerant oil and refrigerant R134a corrodes cer‐ tain metals (e.g. copper) and alloys and dissolves certain hose materials. Therefore, always use genuine spare parts.

The pipes and hoses are held together by bolted joints or by way of special connectors.

Note

Observe specified torques for bolted connections and use the envisaged release tools for connectors.

2. General information on refrigerant circuit 27

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2.2.12 Pressure relief valve

The pressure relief valve is attached to the air conditioner com‐ pressor or receiver.

The valve opens at a pressure of approx. 38 bar and closes again when the pressure has dropped (approx. 30 bar).

Not all the refrigerant is lost from the system.

Depending on the version, a transparent plastic disc may be at‐ tached which breaks off as soon as the valve is actuated.

2.3 Design of refrigerant circuit

♦ Refrigerant circuit with expansion valve and evaporator

⇒ page 28

♦ Refrigerant circuit with restrictor and reservoir ⇒ page 28

2.3.1 Refrigerant circuit with expansion valve and evaporator

1 - Evaporator

2 - Expansion valve

3 - Valve for extraction, charging and measurement

4 - Inspection port (not fitted with R134a circuits)

5 - Receiver with dryer

6 - Condenser

7 - Air conditioner compressor

Note

Arrows show direction of refrigerant flow.

2.3.2 Refrigerant circuit with restrictor and reservoir

1 - Air conditioner compressor

2 - Condenser

3 - Restrictor

4 - Evaporator

5 - Reservoir

Note

Arrows show direction of refrigerant flow.

28 Rep. gr.87 - Air conditioning system

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2.4 Quick-release coupling connections in refrigerant circuit

• Only valves and connections resistant to R134a refrigerant

and the related refrigerant oils are to be used.

• There are different connections (OD) for the high and low

pressure ends.

• Discharge the refrigerant circuit before removing valves or

valve inserts.

• Always screw on sealing caps.

Arrangement in vehicle ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦ Connections with Schrader valve (needle valve) ⇒ page 29

♦ Connections with primary sealing valve (ball valve)

⇒ page 30

2.4.1 Connections with Schrader valve (nee‐ dle valve)

♦ -A- Service connection (soldered in)

♦ -B- Valve insert (designation: Schrader or needle valve)

♦ -C- O-ring (for valve)

♦ -D- Sealing cap with seal

Note

♦

Following connection, carefully screw the handwheel of the service coupling into the quick-release coupling adapter to the extent required to reliably open the valve in the service con‐ nection (observe the pressure gauge; take care not to open the valve too far).

♦

To remove and install the valve insert -B- with the refrigerant circuit drained, make use of an adapter from the socket T10364- for example.

♦

Take care when tightening the valve insert -B- on account of the low tightening torque.

♦

There are different versions of these valves and the tightening torques therefore also differ. The tightening torque for a valve insert -B- with a VG5 thread (5.2 x 0.7 mm, tyre valve) is

0.4 Nm+- 0.1 Nm. For a valve insert with an M6 x 0.75 mm thread, the tightening torque is 0.9 Nm+- 0.1 Nm and for a valve insert with an M8 x 1.0 mm thread it is 2.0 Nm+- 0.2 Nm.

♦

There are different versions of these valves, the valve inserts and the corresponding sealing caps. Attention is to be paid to the correct version of the valve insert and correct assignment of the sealing caps ⇒ Electronic parts catalogue .

2. General information on refrigerant circuit 29

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2.4.2 Connections with primary sealing valve (ball valve)

WARNING

Before unscrewing the connection, connect the air conditioner service station and extract refrigerant. The refrigerant circuit must be empty; danger of injury.

Connection with high-pressure valve

1 - Socket with internal thread (soldered in)

2 - O-ring (version and marking: Black or coloured ⇒ Electronic

parts catalogue )

3 - Valve with external thread and groove for O-ring (designa‐

tion: Ball valve)

4 - Seal for sealing cap

5 - Sealing cap

Note

♦

Following connection, carefully screw the handwheel of the service coupling into the quick-release coupling adapter to the extent required to reliably open the valve in the service con‐ nection (observe the pressure gauge; take care not to open the valve too far).

♦

To remove and install the valve -3- with the refrigerant circuit drained, make use of an adapter from the socket -T10364- for example.

♦

There are different versions of these valves (with internal or external thread) and the tightening torques may therefore also differ. The tightening torque for the valves -3- used at present with an M12 x 1.5 mm external thread is 9 Nm +- 1 Nm.

♦

There are different versions of these valves and the corre‐ sponding sealing caps. Attention is to be paid to the correct version of the valve and correct assignment of the sealing cap ⇒ Electronic parts catalogue .

30 Rep. gr.87 - Air conditioning system

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Connection with low-pressure valve

1 - Socket with external thread and groove for O-ring (soldered

in)

2 - O-ring (version and marking: Black or coloured ⇒ Electronic

parts catalogue )

3 - Valve with internal thread

4 - Seal for sealing cap

5 - Sealing cap

Note

♦

Carefully screw the handwheel of the service coupling into the quick-release coupling adapter to the extent required to relia‐ bly open the valve in the service connection (observe the pressure gauge; take care not to open the valve too far).

♦

To remove and install the valve -3- with the refrigerant circuit drained, make use of an adapter from the socket -T10364- for example.

♦

There are different versions of these valves (with internal or external thread) and the tightening torques may therefore also differ. The tightening torque for the valves -3- used at present with an M10 x 1.25 mm internal thread is 9 Nm +- 1 Nm.

♦

There are different versions of these valves and the corre‐ sponding sealing caps. Attention is to be paid to the correct version of the valve and correct assignment of the sealing cap ⇒ Electronic parts catalogue .

2.5 Switches and senders in refrigerant cir‐ cuit and related connections

Note

Refer to vehicle-specific refrigerant circuit for switching pres‐ sures, switch removal/installation and switch layout/design ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦ High-pressure switch for air conditioning system -F23-

⇒ page 32

♦ High-pressure switch for magnetic clutch -F118-

⇒ page 32

♦ Low-pressure switch for air conditioning system -F73-

⇒ page 32

♦ Air conditioning system pressure switch -F129- ⇒ page 33

♦ High-pressure sender -G65- ⇒ page 33

♦ Refrigerant pressure and temperature sender -G395-

⇒ page 34

♦ Connections with valve for switches in refrigerant circuit

⇒ page 32

♦ Air conditioner compressor regulating valve -N280-

⇒ page 34

♦ Air conditioning system compressor speed sender -G111-

⇒ page 35

2. General information on refrigerant circuit 31

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♦ Refrigerant temperature sender -G454- ⇒ page 35

2.5.1 High-pressure switch for air conditioning system -F23-

Function:

Switches the radiator fan up to the next speed setting in the event of a pressure increase in the refrigerant circuit (approx. 16 bar).

2.5.2 High-pressure switch for magnetic clutch -F118-

Function:

Switches off the air conditioner compressor in the event of excess pressure in the refrigerant circuit (approx. 32 bar).

2.5.3 Low-pressure switch for air conditioning system -F73-

Function:

Switches off the air conditioner compressor in the event of a pres‐ sure drop in the refrigerant circuit (approx. 2 bar).

2.5.4 Connections with valve for switches in refrigerant circuit

• There are different threads for switches on the high and low

pressure ends.

• Only valves and O-rings resistant to R134a refrigerant and the

related refrigerant oils are to be used.

A - Connection (soldered in)

B - O-ring

C - Valve (with O-ring)

Note

To remove and install the valve insert -C- with the refrigerant cir‐ cuit drained, make use of an adapter from the socket -T10364for example (tightening torque ⇒ page 29 ).

32 Rep. gr.87 - Air conditioning system

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2.5.5 Air conditioning system pressure switch

-F129-

This pressure switch has 3 functions:

1. Switches the radiator fan up to the next speed setting in the event of a pressure increase (approx. 16 bar) in the refrigerant circuit.

2. Switches off the air conditioner in the event of excessive pres‐ sure (approx. 32 bar) caused for example by inadequate engine cooling.

3. Switches off the air conditioner in the event of insufficient pres‐ sure (approx. 2 bar) caused for example by a loss of refrigerant.

Note

The air conditioning system pressure switch -F129- replaces the high-pressure switch for air conditioning system -F23- , the lowpressure switch for air conditioning system -F73- and the highpressure switch for magnetic clutch -F118- .

2.5.6 High-pressure sender -G65-

The high-pressure sender -G65- is fitted instead of the air condi‐ tioning system pressure switch -F129- or the refrigerant pressure and temperature sender -G395- .

The refrigerant pressure and temperature sender -G395- („grey“ housing at present) and the high-pressure sender -G65- („black“ housing at present) currently only differ in terms of the housing colour and attention is therefore to be paid to the correct assign‐ ment on replacement (part number ⇒ Electronic parts catalogue ). As these two senders emit different signals, the relevant control unit can only evaluate the signal to which it has been matched ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

The high-pressure sender -G65- generates a square-wave signal or data telegram when voltage is applied. This signal changes with the pressure in the system.

The downstream control units (radiator fan control unit, engine control unit, operating and display unit for Climatronic air condi‐ tioning system -E87- , Climatronic control unit -J255- etc.) use this signal to calculate the pressure in the refrigerant circuit and to actuate the radiator fans and the air conditioning system magnetic clutch -N25- accordingly or to modify actuation of the air condi‐ tioner compressor regulating valve -N280- ⇒ Heating, air condi‐ tioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual).

2. General information on refrigerant circuit 33

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2.5.7 Refrigerant pressure and temperature sender -G395-

The refrigerant pressure and temperature sender -G395- is fitted instead of the high-pressure sender -G65- .

The refrigerant pressure and temperature sender -G395- („grey“ housing at present) and the high-pressure sender -G65- („black“ housing at present) currently only differ outwardly in terms of the housing colour and attention is therefore to be paid to the correct assignment on replacement (part number ⇒ Electronic parts catalogue ). As these two senders emit different signals, the rel‐ evant control unit can only evaluate the signal to which it has been matched ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air con‐ ditioning; Rep. gr. 87 (vehicle-specific workshop manual).

When voltage is applied, the refrigerant pressure and tempera‐ ture sender -G395- exchanges information via the air conditioner data bus („Lin bus“) with the corresponding control unit. The rel‐ evant control unit uses this information to calculate the pressure and temperature in the refrigerant circuit and any faults detected are signalled to the control unit.

The temperature measured by the refrigerant pressure and tem‐ perature sender -G395- differs on account of the design of -G395and the fitting location from the actual temperature of the refrigerant in the refrigerant circuit. It is therefore not evaluated at present by all control units and used for air conditioner control ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

This information is used for example by the operating and display unit, Climatronic control unit -J255- to calculate the pressure in the refrigerant circuit and to actuate the downstream control units (radiator fan control unit, engine control unit etc.) by way of the data bus. These control units then regulate, for example, the ra‐ diator fans and engine accordingly ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

2.5.8 Air conditioner compressor regulating valve -N280-

The regulating valve is installed in the air conditioner compressor. It is actuated by the operating and display unit for Climatronic air conditioning system -E87- or the Climatronic control unit -J255(possibly via the data bus and an additional control unit depending on the vehicle) ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual). The pressure on the low-pressure end is influenced by the regu‐ lating valve, thus regulating the temperature in the evaporator.

Note

The air conditioner compressor regulating valve -N280- is part of the air conditioner compressor and cannot be replaced separate‐ ly.

34 Rep. gr.87 - Air conditioning system

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2.5.9 Air conditioning system compressor speed sender -G111-

Inductive sender

The sender pulses (4 per compressor revolution) and the engine speed enable the operating and display unit for Climatronic air conditioning system -E87- or the Climatronic control unit -J255to calculate the belt slip.

If the belt slip exceeds a specified value, the air conditioner com‐ pressor is switched off by the control unit via the magnetic clutch.

Note

♦

Fitted in Audi vehicles with compressor driven via poly V-belt and Zexel compressor ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific work‐ shop manual).

♦

The logo of the compressor manufacturer „Zexel“ affixed to the air conditioner compressor was switched as of year of pro‐ duction 2006 (when the manufacturer's name changed) from „Zexel“ to the new name „Valeo“.

2.5.10 Refrigerant temperature sender -G454-

The refrigerant temperature sender (with a temperature-sensitive resistor) is installed, for example, in the high-pressure line next to the air conditioner compressor.

In the refrigerant circuit, there is a direct relationship between temperature and pressure. If there is insufficient refrigerant in the circuit, the temperature in the refrigerant circuit during air condi‐ tioner operation will increase more sharply than envisaged for this pressure.

Note

♦

Fitted, for example, on the Audi Q7 with certain engines ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Current flow diagrams, Electrical fault finding and Fitting locations

♦

The operating and display unit, Climatronic control unit -J255evaluates the pressure and the temperature in the refrigerant circuit and switches off the air conditioner compressor if the temperature increases above the value stored for this pres‐ sure ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific work‐ shop manual) and ⇒ Vehicle diagnostic tester („Selfdiagnosis“ or „Guided fault-finding“ function for the air conditioner).

2.6 Electrical components not installed in refrigerant circuit

♦ Radiator fan control unit -J293- ⇒ page 36

2. General information on refrigerant circuit 35

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2.6.1 Radiator fan control unit -J293-

This control unit activates and deactivates the magnetic clutch and thus the air conditioner compressor. It switches the radiator fans and calculates the pressure in the refrigerant circuit on ve‐ hicles with a high-pressure sender -G65- . Refer to ⇒ Current flow diagrams, Electrical fault finding and Fitting locations, ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

2.7 Pressures and temperatures in refriger‐ ant circuit

Caution

♦ When working on the refrigerant circuit, observe the gen‐

erally valid safety precautions and pressure vessel regu‐ lations.

The pressures and temperatures in the refrigerant circuit depend on the instantaneous operating statuses (e.g. engine speed, ra‐ diator fan speed 1, 2, or 3, engine temperature, air conditioner compressor on or off) as well as environmental influences (e.g. ambient temperature, humidity, required cooling output).

On vehicles with air conditioner compressor regulating valve N280- the pressure on the low pressure end is altered by actuat‐ ing -N280- .

For these reasons, the values given in the following table are only to be taken as a guide. They are attained at an engine speed of 1500 to 2000 rpm and an ambient temperature of 20 °C after about 20 minutes.

Refer to the vehicle-specific refrigerant circuit for the pressure gauge set measurement connections ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

At 20 °C with the engine not running, the pressure in the refrig‐ erant circuit is 4.7 bar ⇒ page 4 (vapour pressure table).

Note

Pressure may be given in various units: 1 MPa (megapascal) cor‐ responds to 10 bar gauge pressure or 145 psi; 1 bar absolute pressure corresponds to 0 bar gauge pressure, which is roughly equivalent to atmospheric pressure.

♦ Refrigerant circuit with expansion valve ⇒ page 36

♦ Refrigerant circuit with restrictor and reservoir ⇒ page 38

2.7.1 Refrigerant circuit with expansion valve

HP(HD) – High-pressure end of refrigerant circuit.

LP(ND) – Low-pressure end of refrigerant circuit.

36 Rep. gr.87 - Air conditioning system

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Component Refrigerant state Pressure (bar) Temperature in degrees

centigrade

-1- Evaporator, from inlet

Vapour

approx. 1.2 bar 1)1 approx. -7 °C 2)2

to outlet

-2- Expansion valve Liquid, expanded to va‐ pour

approx. 14 bar approx. +55 °C (high-

pressure end), reduced to -7 °C (low-pressure end)

-3- High-pressure switch /

Liquid approx. 14 bar approx. +55 °C

high-pressure sender

-4- Service connection/

Liquid approx. 14 bar approx. +55 °C

high-pressure end and

-5- Receiver

-6- Condenser From gas (at inlet) via va‐ pour to liquid (at outlet)

approx. 14 bar From approx. +65 °C (at

inlet) to approx. +55 °C (at outlet)

-7- Pressure relief valve

Gas approx. 14 bar approx. +65 °C

and

-8- Air conditioner com‐

pressor/high-pressure end

-9- Air conditioner com‐

Gas

approx. 1.2 bar 1)1 approx. -1 °C 2)2

pressor/low-pressure end

-10- Damping chamber

Gas

approx. 1.2 bar 1)1 approx. -1 °C 2)2 (not fitted on all vehicles) and

-11- Service connection/ low-pressure end

1) 1 - The pressure in a refrigerant circuit with a regulating air conditioner compressor is maintained at approx. 2 bar absolute (corresponding to approx. 1 bar gauge) despite varying heat transfer and fluctuating engine speeds. This however only applies within the output range of the air conditioner compressor. If the output limits of the air conditioner compressor are exceeded, the pressure will increase

⇒ page 109 .

2) 2 - The temperature in a refrigerant circuit with a regulating air conditioner compressor is maintained within the regulating range of the air conditioner compressor despite varying heat transfer and fluctuating engine speeds. This however only applies within the output range of the air conditioner compressor. If the output limits of the air conditioner compressor are exceeded, the temperature will increase

⇒ page 109 .

Note

♦

Non self-regulating air conditioner compressors are switched off by the relevant control unit via the air conditioner compres‐ sor regulating valve -N280- at evaporator temperatures below 0 °C.

♦

On vehicles with air conditioner compressor regulating valve N280- the pressure on the low pressure end is altered by actuating the valve.

♦

On vehicles with two evaporators and two expansion valves, the temperature and the pressure in the refrigerant circuit cor‐ respond to those on vehicles with only one evaporator and one expansion valve (parallel connection).

♦

Depending on the design of the refrigerant circuit, a compo‐ nent with an internal heat exchanger may be fitted (e.g. on the Audi A4 2008 > and the Audi A5 Coupé 2008 > a refrigerant line with an internal heat exchanger). In the internal heat ex‐ changer, the hot liquid refrigerant flowing on the high-pressure end supplies energy to the cold refrigerant gas or vapour flow‐ ing on the low-pressure end, thus enhancing the efficiency of the air conditioner ⇒ page 25 .

2. General information on refrigerant circuit 37

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Arrows show direction of refrigerant flow.

HP(HD) – High-pressure end of refrigerant circuit.

LP(ND) – Low-pressure end of refrigerant circuit.

1 - Evaporator

2 - Expansion valve

3 - High-pressure switch / highpressure sender

❑ Different versions de‐

pending on vehicle

4 - Service connection/highpressure end

5 - Receiver

❑ Different versions de‐

pending on vehicle

6 - Condenser

7 - Pressure relief valve

8 - Air conditioner compressor/ high-pressure end

9 - Air conditioner compressor/ low-pressure end

10 - Damping chamber

❑ Not fitted on all vehicles

11 - Service connection/lowpressure end

2.7.2 Refrigerant circuit with restrictor and reservoir

HP(HD) – High-pressure end of refrigerant circuit.

LP(ND) – Low-pressure end of refrigerant circuit.

Component Refrigerant state Pressure (bar) Temperature in degrees

centigrade

-1- Air conditioner com‐ pressor/high-pressure end

-2- Condenser From gas to vapour to liq‐

-3- Restrictor From liquid to vapour HP end up to 20 bar LP

-4- Evaporator From vapour to gas Greater than 1.0 bar Warmer than -4 °C

-5- Reservoir Gas

Gas Up to 20 bar Up to +70 °C

Up to 20 bar Up to +70 °C

uid

HP end up to +60 °C LP

end greater than 1.0 bar

end warmer than -4 °C

38 Rep. gr.87 - Air conditioning system

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Component Refrigerant state Pressure (bar) Temperature in degrees

-6- Air conditioner com‐

Gas

pressor/low-pressure end

The pressures on the low-pressure end are maintained at approx. 2 bar absolute (corresponding to approx. 1 bar gauge) by the „regulating“ air conditioner compressor even at varying engine speeds. This however only applies within the output range of the air conditioner compressor. If the output limits of the air condi‐ tioner compressor are exceeded, refer to ⇒ page 109 .

Note

On vehicles with air conditioner compressor regulating valve N280- the pressure on the low pressure end is altered by actuat‐ ing the valve.

Arrows show direction of refrigerant flow.

HP(HD) – High-pressure end of refrigerant circuit.

LP(ND) – Low-pressure end of refrigerant circuit.

centigrade

1 - Air conditioner compressor/ high-pressure end

2 - Condenser

3 - Restrictor

4 - Evaporator

5 - Reservoir

6 - Air conditioner compressor/ low-pressure end

2. General information on refrigerant circuit 39

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2.8 Test and measurement operations which can be performed with a pressure gauge

Indicated on pressure gauge

1 - Temperature scale for refrigerant R134a CF3– CH2F or

CH2F– CF3

2 - Pressure scale

Note

Pressure may be given in various units: 1 MPa (megapascal) cor‐ responds to 10 bar gauge pressure or 145 psi; 1 bar absolute pressure corresponds to 0 bar gauge pressure, which is roughly equivalent to atmospheric pressure.

In addition to the pressure scale, pressure gauges may have one or more temperature scales. The scale values for R134a are as‐ signed according to the vapour pressure table. As different re‐ frigerants develop different vapour pressures at the same temperature, each temperature scale is marked for the appropriate refrigerant.

♦ Pressure gauges permit the following test and measurement

operations ⇒ page 40 .

2.8.1 Pressure gauges permit the following test and measurement operations

Refrigerant circuit pressure and temperature measurements

♦ The high-pressure gauge measures the pressure and tem‐

perature propagated evenly from the air conditioner compres‐ sor outlet via the condenser to the constriction (restrictor or expansion valve) when the air conditioning system is switched on.

♦ The low-pressure gauge measures the pressure and temper‐

ature propagated evenly from the constriction (restrictor or expansion valve) via the evaporator to the inlet of the air con‐ ditioner compressor when the air conditioning system is switched on.

Note

The relationship between pressure and temperature indicated on the pressure gauges only exists in a refrigerant circuit containing liquid or vapour, but not gas. In the gas state, the temperature is approx. 10 °C to 30 °C higher than the pressure gauge reading.

Detection of refrigerant in a closed vessel

Refrigerant R134a is present in a closed vessel or in the refrig‐ erant circuit if the temperature indicated on the pressure gauge corresponds to the temperature of the refrigerant (standing liquid assumes ambient temperature).

A closed vessel or a deactivated refrigerant circuit is empty if the temperature indicated on the pressure gauge is below the tem‐ perature of the refrigerant.

40 Rep. gr.87 - Air conditioning system

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Note

The relationship between pressure and temperature indicated on the pressure gauges no longer applies if no liquid is present and the pressure is built up solely by gas.

2.9 Air conditioner service and recycling units

Air conditioner service units for the extraction, cleaning and trans‐ fer of refrigerant for motor vehicle air conditioning systems are currently available from various manufacturers.

Only certain air conditioner service stations (with appropriate ad‐ ditional equipment and various adapters if applicable) can be used for flushing the refrigerant circuit ⇒ page 64 .

♦ Classification of extraction systems ⇒ page 41

♦ Charging systems not requiring a permit ⇒ page 42

2.9.1 Classification of extraction systems

WARNING

When working on the refrigerant circuit and handling refriger‐ ant, observe the generally valid safety precautions and pres‐ sure vessel regulations.

Note

♦

The air conditioner service and recycling units used in motor vehicle workshops are extraction and charging systems not requiring a permit (Group „3“) but which are only to be oper‐ ated by qualified personnel. Instructions for the operation and maintenance of the devices can be found in the respective manufacturer's documentation.

♦

Extraction and charging systems of groups „1“ and „2“ are not used in motor vehicle workshops.

Group „3“ extraction and charging systems:

Mobile extraction and charging systems for filling compressedgas vessels permanently connected to the system

The refrigerant or refrigerant/oil mixture is transferred to com‐ pressed-gas vessels which are permanently connected to the mobile systems. According to §3 Paragraph 5 No. 3 of the Ger‐ man pressure vessel regulations (different regulations may apply in other countries), compressed-gas vessels are classified as pressure vessels in this case.

The charging systems:

– Do not require a permit.

– Do not require expert testing, as the gas is transferred to com‐

pressed-gas vessels which are classed as being pressure vessels (by contrast, a permit is required for the system for filling compressed-gas vessels from these pressure vessels for transfer to other parties and testing is mandatory).

2. General information on refrigerant circuit 41

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2.9.2 Charging systems not requiring a permit

WARNING

When working on the refrigerant circuit and handling refriger‐ ant, observe the generally valid safety precautions and pres‐ sure vessel regulations.

Charging systems not requiring a permit are ones used for trans‐ ferring compressed gases to mobile compressed-gas vessels for internal use only.

Note:

Some air conditioner service units are charging systems not re‐ quiring a permit. When working with such equipment, the refrig‐ erant is not transferred to mobile compressed-gas vessels, but rather into a permanently installed charging cylinder with visible level gauge and float switch.

Recommendation:

It is advisable to use a portable cylinder with visible level gauge and pressure relief valve for surplus refrigerant for internal use.

TRG 402 (technical regulations for compressed gases) must be observed when filling other compressed-gas vessels with com‐ pressed gases.

2.10 Repair information for refrigerant circuit

WARNING

♦ When working on the refrigerant circuit, observe the gen‐

erally valid safety precautions and pressure vessel regu‐ lations.

Special tools and accessories:

The performance of proper workmanlike repairs on an air condi‐ tioning system

• Requires the use of special tools and materials as listed in

⇒ page 199 .

• Requires compliance with the basic instructions for use of leak detectors ⇒ page 92 .

• Requires expert knowledge.

Note

Releasing refrigerant into the environment is prohibited

⇒ page 43 (laws and regulations).

42 Rep. gr.87 - Air conditioning system

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3 Laws and regulations

Note

The laws and regulations listed below are valid in Germany. Other or additional laws and regulations may apply in other countries.

♦ Laws and regulations ⇒ page 43

3.1 Laws and regulations

Nowadays the effects of climate change can be seen throughout the world. Climate protection is thus one of the most important problems to be tackled. Solving this problem does however rep‐ resent an enormous challenge for everybody.

One aspect of the Kyoto protocol is the definition of the worldwide climate protection targets. This protocol contains reduction tar‐ gets both for carbon dioxide and fluorinated greenhouse gases, e.g. for the refrigerant R134a on account of the high greenhouse potential.

A number of laws of relevance to the automobile industry have been passed at European level for example. In Germany for ex‐ ample, the climate protection regulation on chemicals additionally came into force on 1st August 2008 to set down the European legislation more precisely.

♦ Regulation (EC) no. 2037/2000

♦ Regulation (EC) no. 842/2006

♦ Regulation (EC) no. 706/2007

♦ Regulation (EC) no. 307/2008

♦ Directive 2006/40/EC

♦ Climate protection regulation on chemicals, recycling and re‐

fuse law (for Germany).

Maintenance and repair work on air conditioner refrigerant circuits

Anyone performing maintenance and repair work on motor vehi‐ cle air conditioning systems must have received the relevant instruction or attended a training course and be able to furnish certification of the appropriate qualifications. Other or additional regulations may apply in countries outside the European Com‐ munity.

The following is however generally applicable:

Operation, maintenance, shutdown, obligation to accept return

♦ With regard to the operation, repair and shutdown of items

containing refrigerants, it is prohibited to contravene the state of the art by allowing the substances contained in these to escape into the atmosphere.

♦ A record should be kept of the quantities used during operation

and for maintenance work ⇒ Audi-ServiceNet, HSO Environ‐ mental Protection to be able to submit certification of use to the relevant authorities on request. According to a regulation of the European parliament from 2005, it is no longer neces‐ sary to keep a record sheet in the EC. Other regulations may apply in countries not belonging to the EC.

♦ Distributors of the substances and preparations listed in the

above-mentioned regulations are obliged to take back such substances and preparations after use or to ensure that these are taken back by a third party appointed by the distributor.

3. Laws and regulations 43

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♦ The maintenance and shutdown of items containing refriger‐

ants listed in the regulations mentioned as well as acceptance of return of the substances and preparations listed in these regulations may only be undertaken by persons with the nec‐ essary expert knowledge and technical equipment.

Criminal offences and infringements of the law

♦ An infringement in terms of the regulations and laws men‐

tioned above is constituted by any wilful or negligent action during the operation, maintenance or shutdown of items con‐ taining the refrigerants mentioned which allows substances contained in these to escape into the atmosphere contrary to the state of the art or by the wilful or negligent contravention of the applicable regulations and laws mentioned above.

TRG (technical regulations for compressed gases) 400, 401, 402

Note

Only excerpts from the TRG are given in the following (sections applicable to motor vehicle manufacturers and workshops).

♦ TRG 400 (general regulations for charging systems)

– Definition of terms and explanatory notes

– Charging systems

– Charging systems are systems for filling mobile compressed-

gas vessels. The associated premises and facilities form part of the charging system.

– Charging systems requiring a permit

Note

♦

Charging systems requiring a permit are ones used to transfer compressed gases to mobile compressed-gas vessels for supplying to third parties.

♦

Charging systems not requiring a permit are ones used for transferring compressed gases to mobile compressed-gas vessels for internal use only.

♦ TRG 401 (installation of charging systems)

– Does not apply to vehicle manufacturers or workshops.

♦ TRG 402 (operation of charging systems)

– Employees and the instruction of employees

Note

Employees are to be given instruction on the following topics be‐ fore beginning work and at regular, appropriate intervals, however at least once a year:

• Hazards specifically associated with handling compressed gases

• Safety regulations, particularly the applicable TRG

• Procedures in the event of malfunction, damage and accidents

• The use of fire-extinguishing and protective equipment

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• Operation and maintenance of the charging system on the ba‐ sis of the instructions for use

– Charging systems may only be operated and maintained by

persons:

– Aged 18 and above

– Possessing the necessary technical knowledge.

– Who can be relied upon to work diligently.

Note

Work under supervision may also be performed by persons who fail to comply with the above-mentioned prerequisites.

Charging (a special TRG applies to vessels from other countries and charging of these).

♦ A compressed-gas vessel is only to be filled with the com‐

pressed gas declared on it and the quantity must comply with the stipulated pressure, weight or volume data (refer to pres‐ sure vessel regulations).

♦ In the case of vessels approved for use with several types of

compressed gas, the compressed gas with which it is to be filled and - if the compressed gas has a tc greater than/equal to -10 °C (tc = critical temperature) - the maximum permissible charging weight in line with TRG 104 must be marked on the vessel prior to connection for filling.

♦ Compressed-gas vessels marked with the maximum permis‐

sible charge pressure in bar at 15 °C must be filled manomet‐ rically. If, at the time of filling, the temperature is not 15 °C, the pressure corresponding to the prevailing temperature must be established; it must be ensured that the permissible charge pressure at 15 °C is not exceeded in the compressed-gas vessel. To determine possible overfilling, the charged vessels must be checked by way of random pressure measurements.

♦ Compressed-gas vessels on which the maximum permissible

capacity is indicated by the net weight (filling weight, permis‐ sible weight of fill) in kilograms must be filled gravimetrically. The vessels are to be weighed during filling and subsequently subjected to a weight check on special scales to establish possible overfilling. Scales used for this purpose must be cali‐ brated.

♦ Under certain conditions, gases with a tc greater than/equal to

+70 °C may be transferred volumetrically from compressedgas vessels with a maximum volume of 150 l to compressedgas vessels with a volume of max. 1000 ccm. The stipulations of the TRG apply to filling workmen's cylinders with liquefied gas.

♦ The following TRG apply to vessels in vehicles:

– TRG 101 to gases with a tc greater than/equal to +70 °C.

– TRG 102 or TRG 103 to industrial gas mixtures with a tc great‐

er than/equal to +70 °C:

– Liquefied extremely low-temperature compressed gases (re‐

fer to TRG 103) may also be filled volumetrically (with the exception of vessels in vehicles) if the charging system and/ or the vessels is/are equipped with devices for measuring or limiting the volume of the charge and for measuring the tem‐ perature of the charge. When filling volumetrically, it must be ensured that the permissible charge weight indicated on the vessel is not exceeded. To determine possible overfilling, the charged vessels are to be checked gravimetrically on calibra‐

3. Laws and regulations 45

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ted scales or volumetrically, provided that the compressed gases are not highly toxic. Volumetric checking requires the use of appropriate equipment with completely separate charg‐ ing and checking devices.

♦ Charging and check measurements are to be performed by

different people. Check measurements must be performed immediately upon conclusion of the filling process.

♦ Overfilled vessels must be discharged immediately and in a

safe manner down to the permissible fill quantity. The com‐ pressed-gas fill is then to be determined again.

♦ Numbers 4 to 7 do not apply to vessels for liquefied, extremely

low-temperature compressed gases which are neither flam‐ mable nor toxic; this does not affect the provisions of road traffic legislation.

♦ When filling compressed gas vessels with liquified gases at

charging temperatures less than/equal to -20 °C, the com‐ pressed gas vessel (if the vessel material has not been tested for temperatures less than/equal to -20 °C) is not to be re‐ leased from the charging system for transportation until the vessel wall temperature is greater than/equal to +20 °C.

Recycling and refuse law

♦ Regulations and rules for the handling and disposal of refrig‐

erants and refrigerant oils can be found in the climate protec‐ tion regulation on chemicals and in the recycling and refuse law (applicable in Germany, different regulations and rules may apply in other countries).

Disposal of refrigerant

Refrigerants intended for disposal are to be transferred to marked recycling containers, observing the permissible filling quantity. In Germany, reference should be made for example to the climate protection regulation on chemicals and the recycling and refuse law (different regulations and rules may apply in other countries).

Disposal of refrigerant oil

Used refrigerant oils from systems employing halogenated hy‐ drocarbons are to be disposed of as waste requiring special monitoring. They are not to be mixed with other oils or substan‐ ces. Proper storage and disposal must be ensured in line with local regulations. In Germany, reference should be made for ex‐ ample to the climate protection regulation on chemicals and the recycling and refuse law (different regulations and rules may ap‐ ply in other countries) ⇒ Audi-ServiceNet, HSO Environmental Protection .

♦ Conversion of an R12 refrigerant circuit to an R134a refriger‐

ant circuit and servicing (retrofit) ⇒ page 47

♦ Maintaining records on refrigerant ⇒ page 47

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3.1.1 Conversion of an R12 refrigerant circuit

to an R134a refrigerant circuit and serv‐ icing (retrofit)

Note

♦

For environmental reasons and on account of the correspond‐ ing legislation, refrigerant R12 can no longer be manufactured or supplied. Refrigerant R134a has been developed as a re‐ placement for R12.

♦

However, air conditioning systems developed and designed for refrigerant R12 cannot simply be charged with refrigerant R134a. To ensure trouble-free operation of the air conditioning system even after a retrofit, various components of the refrig‐ erant circuit must be replaced.

♦

A precise description of the conversion procedure and infor‐ mation on the servicing of converted refrigerant circuits can be found in ⇒ Workshop Manual: Air conditioner with refrigerant R12 Parts 2 and 3 (this Workshop Manual is only available in hardcopy form).

3.1.2 Maintaining records on refrigerant

The environmental statistics law requires records to be kept on the use of refrigerants exceeding a certain quantity per year.

Consequently, motor vehicle workshops may well have to provide the relevant local authorities with information on their use of re‐ frigerant. It is therefore advisable to always keep a record sheet ⇒ Audi-ServiceNet, HSO Environmental Protection .

Note

♦

On the basis of a regulation of the European parliament from 2005, it is generally no longer necessary in the EC to keep a record sheet for the quantity of refrigerant handled in motor vehicle workshops. A record sheet is currently only necessary as of an annual consumption of 50 kg or more (refer also to directive (EC) No. 1005/2009 for example).

♦

As the relevant local authorities may demand information on refrigerant consumption as of a certain quantity (currently as of 20 kg per year), it is advisable to always keep an appropriate record sheet.

♦

Other regulations may apply in countries not belonging to the EC.

3. Laws and regulations 47

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4 Refrigerant circuit

♦ Important repair information for air conditioning systems

⇒ page 48

♦ Conversion of refrigerant circuits from refrigerant R12 to

R134a ⇒ page 48 .

♦ Working with the air conditioner service station ⇒ page 49 .

♦ Blowing out the refrigerant circuit with compressed air and ni‐

trogen ⇒ page 60 .

♦ Flushing (cleaning) the refrigerant circuit with refrigerant

R134a ⇒ page 64 .

♦ Determination of refrigerant circuit leaks ⇒ page 92 .

4.1 Important repair information for air con‐ ditioning systems

• Air conditioners for refrigerant R12 may only be filled with re‐

frigerant R134a if certain prerequisites are satisfied

⇒ page 47 and ⇒ Workshop Manual: Air conditioner with re‐

frigerant R12 Part 2 and 3 . This Workshop Manual is only available in hardcopy form.

• The refrigerant oils specifically developed for R134a and R12

refrigerant circuits are never to be mixed.

• Air conditioner service stations which come in contact with the

refrigerant are only to be used for the intended refrigerant.

• The components of an R134a refrigerant circuit are accord‐

ingly labelled, marked with green stickers or designed (e.g. a different thread) such that interchange with components for refrigerant R12 is not possible.

• The refrigerant being used is indicated by a label affixed to the

lock carrier in the engine compartment or in the plenum cham‐ ber.

• Different refrigerants are never to be mixed.

Note

When working on the refrigerant circuit, always heed the infor‐ mation given in the Sections on „Safety measures“ ⇒ page 14 and „Basic rules for working on refrigerant circuit“ ⇒ page 15 .

4.2 Converting refrigerant circuits from R12 refrigerant to R134a

CFC refrigerants are no longer used in the automotive industry.

For conversion of refrigerant circuits from R12 to R134a and servicing converted circuits, refer to

⇒ Workshop Manual: Air conditioner with refrigerant R12 Parts 2 and 3 (this Workshop Manual is only available in hardcopy form).

48 Rep. gr.87 - Air conditioning system

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4.3 Working with the air conditioner service station

Vehicles with start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

All vehicles

Caution

♦ If there is a possibility that chemical substances (sealing

additives) for sealing leaks have been added to the refrig‐ erant circuit from which the refrigerant is to be extracted, do not connect the air conditioner service station to this refrigerant circuit and do not extract the refrigerant.

♦ Chemical substances (sealing additives) for sealing leaks

form deposits in the refrigerant circuit which will impair operation of the air conditioning system and lead to failure of the system (and of the air conditioner service station).

♦ Customers should be informed that the air conditioner in

their vehicle contains substances not approved by Audi and that the system can therefore not be discharged and serviced by your workshop.

4. Refrigerant circuit 49

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Note

♦

Commercially available chemical substances (sealing addi‐ tives) for sealing refrigerant circuit leaks are not approved by Audi AG. Damage to or malfunctioning of the air conditioner or air conditioner service station cannot be precluded as no tests have been performed to establish long-term action, ef‐ fectiveness and material compatibility.

♦

Commercially available sealing additives have different phys‐ ical and chemical properties. They may have a lasting detri‐ mental effect on operation of the air conditioner and air conditioner service station or even be the cause of total failure.

♦

Audi does not permit the use of chemical substances (sealing additives) to seal leaks in the refrigerant circuit.

♦

Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit generally react with the ambient air or the humidity contained in it. They cause malfunctioning of valves and other components with which they come into contact on account of deposits in the refrigerant circuit (and in the air conditioner service station being used). These deposits can‐ not be completely removed from the components (even by flushing).

♦

Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit are normally not outwardly apparent and the identification stickers which should be affixed are usually non-existent. Vehicles with an unknown history should there‐ fore be treated with due caution.

♦

Canisters with built-in filters designed to separate these chem‐ ical substances (sealing additives for sealing leaks) are avail‐ able on the accessories market. As Audi are not aware of the composition and thus the physical and chemical properties of these substances, no information can be given here as to the effectiveness and the separation rate of such filters.

♦

The sealant filter -VAS 6592- available as "Workshop equip‐ ment" provides a certain degree of protection for air condition‐ er service stations. This filter is incorporated between the air conditioner service station and the service connection on the low-pressure end of the vehicle refrigerant circuit (the air con‐ ditioner service station is not to be attached to the service connection on the high-pressure end of the refrigerant circuit for drainage, evacuation and measurement). The filter sepa‐ rates out certain substances added to the circuit to seal re‐ frigerant circuit leaks. It thus prevents the unimpeded and unrestricted ingress of these substances into the air condi‐ tioner service station (together with the refrigerant and refrig‐ erant oil) where they would cause damage. Protection is however only provided if the built-in filter is replaced at regular intervals exactly as specified by the manufacturer in the ap‐ plicable instructions. As Audi do not approve the use of chem‐ ical substances (sealing additives) for sealing leaks in the refrigerant circuit and the composition of such chemical sub‐ stances (sealing additives) marketed for example as so-called „refrigerant circuit sealants“ varies greatly, it is again not pos‐ sible to provide any information on the action and efficiency of the sealant filter -VAS 6592- .

If air conditioner refrigerant circuit repair work has to be performed on a vehicle on which chemical substances (sealing additives) have been added to the refrigerant circuit to seal leaking compo‐ nents (or even if this is just strongly suspected), the customer (vehicle owner) is to be made aware of the following:

♦ The air conditioner refrigerant cannot be extracted on account

of the substances added (sealing additives), as these could

50 Rep. gr.87 - Air conditioning system

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damage the air conditioner service station. The refrigerant must be extracted for example by a company authorised to extract and then dispose of the contaminated refrigerant using the appropriate equipment (e.g. a local refuse disposal com‐ pany specialising in the disposal of refrigerants).

♦ The air conditioner can only be properly repaired by replacing

all the refrigerant circuit components which have come into contact with the sealing additive. The sealing additive may al‐ ready have damaged certain refrigerant circuit components (e.g. the air conditioner compressor regulating valve -N280- ) or lead to damage and subsequent failure shortly after re‐ newed start-up. Furthermore, sealing additive deposits may subsequently work loose in the refrigerant circuit components and then lead to renewed failure of the air conditioner (com‐ plete cleaning of these components with workshop equipment is not possible at present).

Work on the air conditioner refrigerant circuit

♦ Important notes for working with the air conditioner service

station ⇒ page 51 .

♦ Connection of the air conditioner service station for measure‐

ment and testing ⇒ page 52 .

♦ Refrigerant circuit discharge using the air conditioner service

station ⇒ page 53 .

♦ Refrigerant circuit evacuation using the air conditioner service

station ⇒ page 54 .

♦ Refrigerant circuit charging using the air conditioner service

station ⇒ page 58 .

♦ Air conditioner start-up after charging ⇒ page 58 .

♦ Pouring refrigerant into the charging cylinder or storage vessel

of the air conditioner service station ⇒ page 59 .

♦ Air conditioner service station drainage ⇒ page 60 .

4.3.1 Important notes for working with the air conditioner service station

The following must be heeded with regard to operation of air con‐ ditioner service stations (e.g. V.A.G 1885; for currently available air conditioner service stations, refer to ⇒ V.A.G workshop equip‐ ment catalogue ):

– The filters and dryers fitted must be replaced at the latest at

the end of the period of use specified in the corresponding operating instructions.

– If an air conditioner service station is also used to flush the

refrigerant circuit, the dryers and filters fitted are to be replaced more frequently ⇒ page 60 .

– Use is only to be made of refrigerant oils which are also ap‐

proved for the vehicle-specific refrigerant circuit (if applicable, add the refrigerant oil directly to the refrigerant circuit). ⇒ Electronic parts catalogue

In cases of doubt about the composition of the refrigerant extrac‐ ted from the refrigerant circuit, this is not to be re-used even after cleaning in the air conditioner service station.

– In such cases, the air conditioner service station is to be

drained ⇒ page 105 , the system cleaned if necessary and the filters, dryers and refrigerant oil replaced.

– In Germany, for example, contaminated refrigerant can be re‐

turned to the refrigerant supplier in so-called recycling con‐

4. Refrigerant circuit 51

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tainers for recycling or ecological disposal (other or additional regulations may apply in other countries).

Commercially available air conditioner service stations can be classified in 2 groups:

♦ Air conditioner service stations which clean the refrigerant ex‐

tracted from a vehicle for re-use (so-called extraction and recycling stations), e.g. V.A.G 1885 (for currently available air conditioner service stations, refer to ⇒ V.A.G workshop equip‐ ment catalogue ).

♦ Air conditioner service stations which transfer extracted re‐

frigerant to recycling containers (for large-scale recycling); these are referred to as extraction systems.

4.3.2 Connecting air conditioner service sta‐ tion for measurement and testing

• The work procedure may vary depending on the type of tools

selected (the tool-specific operating instructions should there‐ fore be heeded).

Note

The work procedure is always to be performed as described in the operating instructions of the air conditioner service station.

To prevent air or moisture entering the refrigerant circuit through the charging hoses, these are to be connected as follows:

– Switch off the ignition.

– Connect the air conditioner service station to the power sup‐

ply.

– Unscrew the sealing caps from the service connections or the

connections with valve (refer to vehicle-specific refrigerant cir‐ cuit) ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

– Evacuate the charging hoses if necessary.

– Connect a quick-release coupling to the service connection of

the refrigerant circuit.

WARNING

♦ Do not open the valves on the low or high-pressure end

with the engine running, as otherwise the air conditioner compressor or the air conditioner service station could be destroyed by a short circuit between the high and lowpressure ends of the refrigerant circuit if the air condition‐ ing system is switched on.

– Only screw the handwheel into the quick-release coupling

adapter to the extent required to reliably open the valve in the service connection (observe the pressure gauge; take care not to open the valve too far).

– Start the engine and perform the intended tests and meas‐

urements.

– Compare the values determined to the specified measured

values ⇒ page 109 .

– Before detaching the quick-release coupling, close it by screw‐

ing out the handwheel.

52 Rep. gr.87 - Air conditioning system

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Vehicles with one service connection only:

Note

Screw the valve adapters -V.A.G 1785/9- , -V.A.G 1785/10- or the adapter set -V.A.G 1786- to the refrigerant circuit connections with valve and bleed the charging hoses during connection to the adapters (only a faintly audible escape of refrigerant gas is per‐ mitted) ⇒ page 105 .

– The charging hose must be fitted with a valve opener to open

the valve in the valve adapter.

4.3.3 Discharging refrigerant circuit with air conditioner service station

• The work procedure may vary depending on the type of tools

selected (heed tool-specific operating instructions).

• The refrigerant circuit must be discharged if parts of the re‐

frigerant circuit are to be removed, if there is any doubt about the quantity of refrigerant in the circuit or if required by the safety precautions.

• All the necessary usage information for working with the re‐

frigerant air conditioner service station can be found in the air conditioner service station operating instructions.

Drainage:

– Switch off the ignition.

– Connect the air conditioner service station in line with the op‐

erating instructions to the vehicle service connections (refer to vehicle-specific refrigerant circuit) and start up the service sta‐ tion ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air condi‐ tioning; Rep. gr. 87 (vehicle-specific workshop manual).

4. Refrigerant circuit 53

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Note

♦

There is a possibility of refrigerant oil being extracted from the refrigerant circuit together with the refrigerant. To ensure air conditioner compressor lubrication, the refrigerant oil in the circuit must be topped up with fresh oil ⇒ page 152 .

♦

On vehicles fitted with an air conditioner compressor with no magnetic clutch (with an air conditioner compressor regulating valve -N280- ), the engine should not be run for longer than absolutely necessary with the refrigerant circuit empty and high engine speeds are to be avoided (constant air conditioner compressor operation).

♦

On vehicles with an air conditioner compressor with no mag‐ netic clutch, the engine is only to be started following complete assembly of the refrigerant circuit (avoid high engine speeds).

♦

Depending on the version of the air conditioner compressor, the high-pressure end of the air conditioner compressor may be fitted with a valve to prevent the backflow of liquid refriger‐ ant into the compressor after switching off the air conditioning system. If an air conditioner compressor with this valve is fitted on a vehicle with a refrigerant circuit with an expansion valve, a relatively long period may elapse before the pressure on the high-pressure end decreases (the expansion valve is cold and the pressure on the low-pressure end increases rapidly after switch-off, the expansion valve closes and the refrigerant can only flow slowly to the low-pressure end). If the air conditioner compressor is switched on (or the refrigerant circuit is dis‐ charged via the low-pressure end), the pressure on the lowpressure end decreases, the expansion valve opens and the refrigerant can flow to the low-pressure end.

4.3.4 Evacuating refrigerant circuit with air conditioner service station

• The work procedure is always to be performed as described

in the operating instructions of the air conditioner service sta‐ tion.

• Quantity of refrigerant oil in refrigerant circuit checked and if

necessary corrected ⇒ page 152 .

• Quantity of refrigerant in air conditioner service station

checked

The refrigerant circuit must be evacuated before it is filled with refrigerant. In addition, moisture is removed from the circuit.

Leaks can be detected on evacuating the refrigerant circuit.

Evacuation:

Caution

♦ The engine is not to be started during evacuation and as

long as there is a vacuum in the refrigerant circuit.

♦ The air conditioner compressor may be damaged if the

engine is started whilst there is a vacuum in the refrigerant circuit.

♦ Always charge the refrigerant circuit before starting the

engine.

– Switch off the ignition.

54 Rep. gr.87 - Air conditioning system

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– Connect the air conditioner service station to the power sup‐

ply.

– Connect the charging hoses of the air conditioner service sta‐

tion to the vehicle refrigerant circuit with quick-release cou‐ pling adapters (refer to vehicle-specific refrigerant circuit) ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

– Screw in the handwheel of the quick-release coupling adapt‐

ers to the extent required to reliably open the valves of the service connections (take care not to open the valve too far).

Note

If the pressure is to be measured after charging the system on vehicles with a service connection on one side of the refrigerant circuit only, use the valve adapter and charging hose with valve opener ⇒ page 105 .

– Switch on the air conditioner service station and evacuate the

refrigerant circuit for at least 30 minutes. In this process, the pressure reading must be less than 10 mbar absolute (corre‐ sponding to a vacuum of 990 mbar).

Note

On the air conditioner service station V.A.G 1885 (for currently available air conditioner service stations, refer to ⇒ V.A.G work‐ shop equipment catalogue ), the two green LEDs light at this pressure for example.

– Switch off the air conditioner service station and allow to stand

for at least 1 hour.

• If the vacuum display (LED chain) does not change, the sys‐ tem is free of leaks and can be charged.

4. Refrigerant circuit 55

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Note

♦

With V.A.G 1885 for example (for currently available air con‐ ditioner service stations, refer to ⇒ V.A.G workshop equip‐ ment catalogue ), a current vacuum display (LED) is only obtained after pressing the Evacuation button again.

♦

If, with this air conditioner service station, the upper (green) LEDs do not light immediately after switching on, either the refrigerant circuit is leaking or there is still residual moisture/ refrigerant in the circuit.

Proceed as follows if the vacuum is not maintained or an ade‐ quate vacuum cannot be generated:

♦ The pressure in the refrigerant circuit only increases slowly

following evacuation, e.g. due to the evaporation of refrigerant from the refrigerant oil.

– If it is not certain whether the refrigerant circuit is really leak-

proof, repeat evacuation and observe the vacuum display over a lengthy period. Charging can only be performed once the vacuum is maintained.

– It it is certain that there are no leaks in the refrigerant circuit,

charging can be performed.

♦ In the event of a leak of such a magnitude that the ingress of

air on evacuation is already sufficient to prevent the air con‐ ditioner service station generating an adequate vacuum or the vacuum gauge already indicates the ingress of air and the loss of vacuum immediately after switching off the air conditioner service station.

– Determine the leakage location in the refrigerant circuit as fol‐

lows:

56 Rep. gr.87 - Air conditioning system

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Note

♦

A major leak can be determined for example by building up a pressure of max. 15 bar in the refrigerant circuit with pure, dry compressed air or with nitrogen ⇒ page 60 . If the leak is of sufficient magnitude, the leakage location will be revealed by the noise of the gas escaping.

♦

Apply the compressed air or the nitrogen to the closed refrig‐ erant circuit by way of the service connection to which a quickrelease coupling adapter for service connections has been attached.

♦

The quick-release coupling adapter for service connections can be connected to the workshop compressed air system using for example a modified charging hose -A- (e.g. with a 5/8"-18 UNF thread, depending on the thread at the quick-re‐ lease coupling adapter) and an appropriate adapter -B-

⇒ page 205 . To prevent the ingress of moisture, oil and dirt

from the workshop compressed air system into the air condi‐ tioner refrigerant circuit, additional use is to be made for ex‐ ample of a combined fine filter unit for compressed air systems (oil, dirt and water separator as used for painting facilities), which is to be fitted between the compressed air system and the charging hose -A- ⇒ Workshop equipment catalogue .

♦

By using a pressure gauge set with pressure reducer for ni‐ trogen (maximum reducing pressure: 15 bar) -1-, a com‐ pressed air cylinder -3- filled with nitrogen can be connected by way of a charging hose -2- (e.g. with a 5/8"-18 UNF thread) to the service connection (to which a quick-release coupling adapter for service connections has been attached) at the closed refrigerant circuit ⇒ page 204 .

– Slowly increase the pressure in the refrigerant circuit to max.

15 bar.

WARNING

♦ There may be an uncontrolled flow of nitrogen out of the

cylinder.

♦ Always work with pressure reducers for nitrogen cylinders

(max. working pressure 15 bar).

♦ For leak detection with nitrogen (max. permissible oper‐

ating pressure 15 bar) always work with pressure reducers for nitrogen cylinders.

♦ Use appropriate extraction units to draw off the gas mix‐

ture escaping from the components.

– Determine the leakage location by way of the noise caused by

the escaping gas at this point.

– Eliminate the leakage.

– Evacuate again and observe the vacuum display over a period

of hours. Charging can only be performed once the vacuum is maintained.

♦ In the event of a leakage of a magnitude permitting the ingress

of no or very little air and the air conditioner service station can generate an adequate vacuum. The vacuum display does not increase or only increases very slowly after switching off the air conditioner service station, indicating that air is only in‐ gressing and vacuum is being lost through a minor leak.

4. Refrigerant circuit 57

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– Pour 100 g of refrigerant into the circuit and use an electronic

leak detector to locate and eliminate any leak ⇒ page 93 or pour in refrigerant with UV contrast medium and use the leak detection system VAS 6201 to search for and eliminate the leak in the refrigerant circuit ⇒ page 95 .

– Discharge the refrigerant circuit if necessary ⇒ page 53 .

– Evacuate the refrigerant circuit and observe the vacuum dis‐

play again over a period of hours. Charging can only be performed once the vacuum is maintained.

4.3.5 Charging refrigerant circuit with air con‐ ditioner service station

Note

The entire refrigerant charge can be added to either the high or low-pressure end ⇒ page 152 .

• The work procedure is always to be performed as described

in the operating instructions of the air conditioner service sta‐ tion.

• Before pouring in refrigerant, correct the quantity of refrigerant

oil ⇒ page 152 .

• When charging the refrigerant circuit, the air conditioner serv‐

ice station must be on the same level as the vehicle in which the refrigerant circuit is to be charged (maximum difference 50 cm). Depending on the design of the air conditioner service station , an excessive difference in height could lead to differ‐ ences between the quantity of refrigerant displayed and that actually poured in. The filling accuracy of the air conditioner service station may vary.

– Switch off the ignition.

– Refrigerant circuit evacuation using the air conditioner service

station ⇒ page 54 .

– Screw out (close) the handwheel on the quick-release cou‐

pling adapter.

– Allow the refrigerant quantity to flow into the charging hose.

– Take the charging cylinder reading.

– Screw in (open) the handwheel on the quick-release coupling

adapter and charge with the specified quantity of refrigerant.

– Switch off the air conditioner service station.

4.3.6 Starting up air conditioner after charging

Note

If it has been removed, give the air conditioner compressor ap‐ prox. 10 turns by hand prior to initial start-up (on or after installa‐ tion, e.g. before fitting the belt) to prevent damage caused by fluid lock when first switched on (any oil in the air conditioner com‐ pressor cylinder is forced out by the cranking action).

58 Rep. gr.87 - Air conditioning system

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Start-up of air conditioner with mechanically driven air conditioner compressor

– Start the engine with the air conditioner compressor switched

off (version with magnetic clutch).

– Set the air conditioner compressor to minimum output, "Econ"

or A/C off mode (version with no magnetic clutch with a regu‐ lating valve).

– Wait for the idling speed to stabilize.

– Switch on the air conditioner compressor and operate the sys‐

tem for at least 2 minutes at idling speed.

– If necessary, check the pressures in the refrigerant circuit with

the air conditioner service station.

– Switch off the engine.

– Screw out the handwheel on the quick-release coupling adapt‐

er.

– Detach the charging hoses from the refrigerant circuit.

– Screw the sealing caps back on.

Start-up of air conditioner with electrically driven air conditioner compressor

– The air conditioner compressor is to be started up by way of

the guided fault-finding „Basic setting, compressor run-in“ function ⇒ Vehicle diagnostic tester function „Guided faultfinding“ for air conditioner and battery control

– If necessary, check the pressures in the refrigerant circuit with

the air conditioner service station on completion of basic set‐ ting.

– Screw out the handwheel on the quick-release coupling adapt‐

er.

– Detach the charging hoses from the refrigerant circuit.

– Screw the sealing caps back on.

4.3.7 Pouring refrigerant into charging cylin‐ der or storage vessel of air conditioner service station

• The work procedure is always to be performed as described

in the operating instructions of the air conditioner service sta‐ tion.

• A certain quantity of refrigerant is specified as charge for each

air conditioning system. To ensure that neither too much nor too little refrigerant is added (either would reduce the cooling output), the charging cylinder has a scale indicating the weight for example.

• The volume of a refrigerant changes as a function of pressure.

The scale must therefore be set according to the pressure in the charging cylinder.

Note

Do not completely empty the charging cylinder or storage vessel, as the liquid column boundary layer cannot be traced in the indi‐ cator tube during filling (outside visible range).

4. Refrigerant circuit 59

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WARNING

Do not overfill. A completely filled charging cylinder or storage vessel will explode when the temperature rises.

4.3.8 Draining air conditioner service station

Note

♦

If it is necessary to drain the air conditioner service station (e.g. due to extraction of contaminated refrigerant), all filters and dryers must always be replaced (do not remove filter and dryer from the air-tight packaging until immediately before installa‐ tion to minimise moisture absorption).

♦

Refrigerant containers filled with contaminated used refriger‐ ant are referred to as „Recycling containers“.

♦

Always evacuate recycling containers before first filling with refrigerant (refrigerant containers are not be filled with refrig‐ erant if they contain any air).

♦

Different types of refrigerant are not to be mixed (refrigerant mixtures cannot be recycled and are to be disposed of). If there is any doubt about the composition of the contents of the con‐ tainer, the refrigerant recycling agent is to be informed ac‐ cordingly.

Caution

♦ When filling recycling containers (compressed-gas ves‐

sels), observe the applicable regulations, technical rules and laws.

♦ Recycling containers must never be overfilled. The gas

cushion in overfilled recycling containers is not sufficient to absorb the liquid expansion caused by the influence of heat. There is a risk of rupturing.

♦ To ensure safety, make exclusive use of recycling con‐

tainers fitted with a safety valve.

♦ Recycling containers must be weighed on calibrated

scales during the filling process. The maximum permissi‐ ble capacity is 75 % (charge factor 0.75) of the charge weight indicated on the recycling container (the possibility of refrigerant oil entering the recycling container along with the refrigerant cannot be ruled out).

4.4 Blowing out refrigerant circuit with com‐ pressed air and nitrogen

All vehicles

The best way of removing moisture, impurities and old refrigerant oil from the refrigerant circuit without any unnecessary loss of re‐ frigerant and without extensive assembly work, whilst at the same time ensuring environmental compatibility, is to flush the refriger‐ ant circuit with refrigerant R134a or to blow it out with compressed air and nitrogen.

60 Rep. gr.87 - Air conditioning system

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Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

Blowing out the refrigerant circuit with compressed air and ni‐ trogen usually involves far more work than flushing with re‐ frigerant R134a. Flushing with refrigerant R134a also provides far better cleaning of the components. Flushing should there‐ fore always be employed in the event of complaints (blowing out should only be applied when dealing with certain problems and for particular components).

♦

Under certain conditions it may, for example, be sufficient to blow out specific components (e.g. individual refrigerant lines or refrigerant hoses) with compressed air and nitrogen (for in‐ stance to force old refrigerant oil out of individual components following removal).

♦

Certain impurities are impossible or difficult to remove properly from the refrigerant circuit using compressed air. Such impur‐ ities can be removed for example by flushing with refrigerant R134a ⇒ page 64 .

♦

A maximum working pressure of 15 bar is not to be exceeded when blowing out (corresponds to the pressure prevailing in a charged refrigerant circuit at an ambient temperature of ap‐ prox. 60 °C; use pressure reducer for compressed air as well if applicable).

WARNING

♦ There may be an uncontrolled flow of nitrogen out of the

cylinder.

♦ Always work with pressure reducers for nitrogen cylinders

(max. working pressure 15 bar).

♦ Use appropriate extraction units to draw off the gas mix‐

ture escaping from the components.

– Always flush or blow out components in the direction opposite

to refrigerant flow.

Note

The restrictor, expansion valve, air conditioner compressor, re‐ ceiver and reservoir cannot be flushed with compressed air and nitrogen.

– In the case of condensers fitted with a dryer cartridge in the

integrated receiver, this cartridge is to be removed.

Note

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately, the condenser is to be replaced after flushing.

♦

Depending on the version, receivers on which the dryer car‐ tridge can be replaced separately may be provided with an additional filter element which may have to be replaced to‐ gether with the dryer cartridge.

4. Refrigerant circuit 61

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

– First flush out the old refrigerant oil and dirt with compressed

air and then use nitrogen to remove the moisture from the components.

– For adapter for attaching pressure hose to refrigerant circuit,

refer to ⇒ page 105 .

Heed the following items to prevent oil and moisture from the compressed-air system ingressing into the refrigerant circuit.

– The compressed air must be passed through a compressed-

air purifier for cleaning and drying. Use is therefore to be made of filters and dryers for compressed air (included in the scope of delivery as tool for painting work) ⇒ Workshop equipment and special tools catalogue .

– For refrigerant lines with a thread or union nut at the connec‐

tion, make use of adapters from the adapter set for refrigerant circuit -V.A.G 1785- ( adapter -V.A.G 1785/1- to adapter V.A.G 1785/8- ) for connection of the 5/8" -18 UNF charging hoses (some of these adapters are also contained in the VW/ Audi passenger vehicle adapter set -VAS 6338/1- ).

– For refrigerant lines with no thread or union nut at the con‐

nection (for connecting adapters), use adapters from the VW/ Audi passenger vehicle adapter set -VAS 6338/1- or a com‐ mercially available blow-out gun with rubber mouthpiece.

Note

♦

The refrigerant circuit is only to be blown out with compressed air and then nitrogen if no means of flushing the refrigerant circuit are available or if flushing of individual components would involve too much work (blowing minor impurities and small quantities of moisture out of refrigerant lines for example is not particularly time-consuming).

♦

Compressed air/nitrogen emerging from the components is to be drawn off by way of an appropriate system (e.g. workshop extraction system).

The refrigerant circuit (or individual components) is/are to be blown out if no means of flushing are available or if flushing seems inappropriate

– In the event of dirt or other impurities in individual circuit com‐

ponents.

– If the vacuum reading is not maintained on evacuating a leak-

free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit).

– If the refrigerant circuit has been left open for longer than the

normal assembly time (e.g. following an accident).

– If pressure and temperature measurements in the refrigerant

circuit indicate the likelihood of moisture.

– If there are doubts about the amount of refrigerant oil in the

refrigerant circuit.

– If the air conditioner compressor has to be replaced on ac‐

count of internal damage (e.g. noise or no output).

– If stipulated by the vehicle-specific workshop manual following

replacement of certain components.

62 Rep. gr.87 - Air conditioning system

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Note

Certain impurities and old refrigerant oil are impossible or difficult to remove properly from the refrigerant circuit using compressed air. Such impurities can be removed for example by flushing with refrigerant R134a ⇒ page 64 .

♦ Blowing out refrigerant circuit ⇒ page 63

4.4.1 Blowing out refrigerant circuit

Note

♦

In the case of vehicles on which the refrigerant lines have no threads for connection of adapters V.A.G -1785- , use is to be made, for example, for blowing out the individual components of a blow-out gun with rubber mouthpiece or an adapter from the VW/Audi passenger vehicle adapter set -VAS 6338/1- . Special care must be taken not to damage the connections (crushing or scratching) when using a blow-out gun with rub‐ ber mouthpiece.

♦

The evaporator is to be blown out by way of the connection for the low-pressure line (large diameter) after detaching the ex‐ pansion valve or removing the restrictor.

♦

Always flush or blow out components in the direction opposite to refrigerant flow.

♦

Examine the expansion valve and replace if dirty or corroded.

♦

If dark, sticky deposits cannot be removed with compressed air, the components concerned are to be flushed with refrig‐ erant R134a or replaced.

♦

Thin, light grey deposits on the insides of pipes do not impair the function of the components.

♦

After flushing, always replace the receiver or reservoir and re‐ strictor. In the case of condensers fitted with a dryer cartridge in the integrated receiver, this cartridge is to be replaced.

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be replaced separately or which is not available as a replacement part, the condenser must be re‐ placed after flushing ⇒ Electronic parts catalogue and ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 .

♦

Depending on the version, receivers on which the dryer car‐ tridge can be replaced separately may be provided with an additional filter element which may have to be replaced to‐ gether with the dryer cartridge.

After blowing out the refrigerant circuit:

– Replace the vehicle-specific components (restrictor and res‐

ervoir, expansion valve and receiver or dryer cartridge) ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Elec‐ tronic parts catalogue .

– Depending on the problem, replace the air conditioner com‐

pressor ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue or drain off the remaining refrigerant oil from the air conditioner compressor removed

⇒ page 143 (replace refrigerant circuit components) and add

the specified quantity of fresh refrigerant oil again

4. Refrigerant circuit 63

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⇒ page 174 (approved refrigerant oils and refrigerant oil ca‐

pacities).

Note

♦

Replacement compressors contain a certain specified quantity of refrigerant oil. For vehicles with two evaporators, it may be necessary to additionally add a certain quantity of refrigerant oil to the circuit ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop man‐ ual) and ⇒ page 174 (approved refrigerant oils and refrigerant oil capacities).

♦

If the air conditioner compressor is not to be replaced, the re‐ frigerant oil quantity in the air conditioner compressor must be topped up in line with the specified capacity (pour out refrig‐ erant oil and add the specified quantity to the air conditioner compressor or the refrigerant circuit again) ⇒ page 143 (re‐ placing refrigerant circuit components) and ⇒ page 174 (ap‐ proved refrigerant oils and refrigerant oil capacities).

– Completely re-assemble the refrigerant circuit ⇒ Heating, air

conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

– Evacuate and charge the refrigerant circuit as specified

⇒ page 54 and ⇒ page 58 .

– Start up the air conditioner as specified ⇒ Heating, air condi‐

tioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual) and ⇒ page 58 .

4.5 Flushing (cleaning) refrigerant circuit with refrigerant R134a

Caution

♦ If there is a possibility that chemical substances (sealing

additives) for sealing leaks have been added to the refrig‐ erant circuit to be flushed, do not connect the air condi‐ tioner service station to this refrigerant circuit and do not flush this refrigerant circuit.

♦ Chemical substances (sealing additives) for sealing leaks

form deposits in the refrigerant circuit which will impair operation of the air conditioning system and lead to failure of the system (and of the air conditioner service station).

♦ Customers should be informed that the air conditioner in

their vehicle contains substances not approved by Audi and that the system can therefore not be flushed and serviced by your workshop.

64 Rep. gr.87 - Air conditioning system

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

Audi does not permit the use of chemical substances (sealing additives) to seal leaks in the refrigerant circuit.

♦

Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit generally react with the ambient air or the humidity contained in it. They cause malfunctioning of valves and other components with which they come into contact on account of deposits in the refrigerant circuit (and in the air conditioner service station being used). These deposits can‐ not be completely removed from the components (even by flushing). The refrigerant circuit can therefore only be repaired by replacing all the components which have come into contact with this substance.

♦

Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit are normally not outwardly apparent and the identification stickers which should be affixed for this pur‐ pose are usually non-existent. Vehicles with an unknown his‐ tory should therefore be treated with due caution.

• The best way of removing moisture, impurities (e.g. abrasion from a defective air conditioner compressor) and old refriger‐ ant oil without any unnecessary loss of refrigerant and without extensive assembly work, whilst at the same time ensuring environmental compatibility, is to flush the refrigerant circuit with refrigerant R134a.

The refrigerant circuit is to be flushed:

– If the event of dirt or other contamination in the circuit.

– If the vacuum reading is not maintained on evacuating a leak-

free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit).

– If the refrigerant circuit has been left open for longer than the

normal assembly time (e.g. following an accident).

– If pressure and temperature measurements in the refrigerant

circuit indicate the likelihood of moisture.

– If there are doubts about the amount of refrigerant oil in the

refrigerant circuit.

– If the air conditioner compressor has to be replaced on ac‐

count of internal damage (e.g. noise or no output).

– If stipulated by the vehicle-specific workshop manual following

replacement of certain components.

Tools required

♦ Air conditioner service station with flushing attachment (these

air conditioner service stations feature the additional function „Flushing refrigerant circuit“ and the necessary flushing at‐ tachment for refrigerant circuits) ⇒ Workshop equipment and special tools catalogue

♦ VW/Audi passenger vehicle adapter set -VAS 6338/1-

⇒ page 77 and ⇒ Workshop equipment and special tools

catalogue

♦

4. Refrigerant circuit 65

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

If no air conditioner service station with flushing attachment is available ⇒ Workshop equipment and special tools catalogue and depending on the version of the air conditioner service station being used, the refrigerant circuit can also be flushed with this employing the refrigerant circuit flushing attachment ⇒ Workshop equipment and special tools catalogue , however flushing must then be performed manually. ⇒ page 70

♦

Use can be made for vehicles with screw connections at the refrigerant circuit of the adapter -V.A.G 1785/7- and adapter V.A.G 1785/8- from the VW/Audi passenger vehicle adapter set -VAS 6338/1- . Two adapters -V.A.G 1785/8- are required for a vehicle with screw connections at the air conditioner compressor and reservoir.

♦

The VW/Audi passenger vehicle adapter set -VAS 6338/1- al‐ so contains a short charging hose -VAS 6338/31- with 5/8 -18 UNF connections and a large inside diameter (commercially available).

Preparation

– Discharge the refrigerant circuit ⇒ page 53 .

– Remove the air conditioner compressor ⇒ Heating, air condi‐

tioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual).

Vehicle with restrictor and reservoir

– Remove the restrictor (vehicle-specific) and re-connect the

lines ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air condi‐ tioning; Rep. gr. 87 (vehicle-specific workshop manual).

– Remove the reservoir (vehicle-specific) and re-connect the

lines (for this purpose, make use of an adapter and the charg‐ ing hose -VAS 6338/31- from the VW/Audi passenger vehicle adapter set -VAS 6338/1- ) ⇒ page 77 , ⇒ Heating, air con‐ ditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

Note

It would be possible to flush the reservoir, however on account of its large internal volume it holds too much liquid refrigerant. On extracting this refrigerant, the reservoir would ice up severely, the refrigerant would only evaporate very slowly and the extraction process would be excessively long.

Vehicle with expansion valve and receiver

– Remove the receiver (vehicle-specific, not necessary with all

vehicles) and re-connect the lines (for this purpose, make use of an adapter and the charging hose -VAS 6338/31- from the VW/Audi passenger vehicle adapter set -VAS 6338/1- )

⇒ page 77 , ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒

Air conditioning; Rep. gr. 87 (vehicle-specific workshop man‐ ual).

66 Rep. gr.87 - Air conditioning system

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Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

Depending on design, the receiver can be flushed (remove the fitted dryer cartridge if applicable) ⇒ page 77 , ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦

If the receiver is attached to the condenser (e.g. on Audi A3 as of Model Year 2004), it is not removed for flushing (its de‐ sign makes it suitable for flushing and it is only replaced after flushing) ⇒ page 77 and ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately or which are not available separately, the condenser is to be replaced after flushing. On these vehicles, the condenser is then to be re‐ placed together with the receiver ⇒ Heating, air conditioning; Rep. gr. 87 and ⇒ Electronic parts catalogue .

♦

Depending on the version, receivers on which the dryer car‐ tridge can be replaced separately may be provided with an additional filter element which may have to be replaced to‐ gether with the dryer cartridge.

– On vehicles with a dryer cartridge in the receiver at the con‐

denser (vehicle-specific), remove the dryer cartridge and reseal the opening at the receiver ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

– Remove the expansion valve (vehicle-specific) and replace it

with an adapter from the VW/Audi passenger vehicle adapter set -VAS 6338/1- ⇒ page 77 , ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

Note

If there is no suitable adapter for the expansion valve in the VW/ Audi passenger vehicle adapter set -VAS 6338/1- , the expansion valve removed can also be drilled open (the old expansion valve generally has to be replaced and is therefore no longer needed).

Caution

♦ Take care not to damage the sealing surfaces at the ex‐

pansion valve when drilling it open.

♦ Refrigerant will escape at damaged sealing surfaces.

4. Refrigerant circuit 67

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

Before drilling open, remove the control element and then drill open the expansion valve using a suitable drill bit for example (bit diameter e.g. 6.0 mm).

♦

Certain components have to be removed from the expansion valve before drilling it open.

♦

There are different expansion valve versions with differing de‐ sign. With version -A-, the parts -B-, -C- and -D- have to be removed for example. Then separate part -E- (control ele‐ ment) from part -D-. After doing so, use a suitable bit to drill open the expansion valve in area -F-.

♦

With version -G-, the parts -H-, -I- and -K- must be removed for example and the area -L- then drilled open using a suitable bit.

– Remove swarf remnants from the expansion valve after drilling

open.

– Re-install the parts -B-, -C- and -D- with version -A- or part

-H- with version -G-.

Note

On vehicles with two evaporators, the circuit to the second evap‐ orator is to be separated from the circuit of the first evaporator and flushed in a separate operation ⇒ page 77 , ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (ve‐ hicle-specific workshop manual).

Flushing

– Check the amount of refrigerant in the air conditioner service

station, it must contain at least 7 kg of refrigerant R134a.

Note

If applicable, switch on the heater attached to the air conditioner service station for the refrigerant cylinder installed in the air con‐ ditioner service station prior to the first flushing operation (to increase the pressure in the refrigerant cylinder) and switch it off again before the first extraction operation during the flushing cy‐ cle.

– Drain the used oil container of the air conditioner service sta‐

tion.

– Connect the supply hose (high-pressure end) of the air con‐

ditioner service station with an adapter to the low-pressure line to the air conditioner compressor (line with larger diameter)

⇒ page 77 .

– Connect the return hose (low-pressure or suction end) of the

air conditioner service station to the outlet of the refrigerant circuit flushing attachment.

– Connect the inlet of the refrigerant circuit flushing attachment

with an adapter to the high-pressure line to the air conditioner compressor (line with smaller diameter) ⇒ page 77 .

68 Rep. gr.87 - Air conditioning system

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Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

The components are always flushed in the direction opposite to that of refrigerant flow during air conditioner operation

⇒ page 72 .

♦

When flushing, impurities from the refrigerant circuit ingress into the refrigerant circuit flushing attachment and the air con‐ ditioner service station, where they are retained in the built-in filters and dryer. Depending on the nature of the impurities, these components are to be replaced more frequently in line with the operating instructions for the air conditioner service station or the refrigerant circuit flushing attachment.

♦

Depending on the nature and severity of the contamination of the flushed refrigerant circuits, the filter in the refrigerant circuit flushing attachment is to be replaced at the latest after 5 to 10 flushing cycles (flushed vehicles). After flushing a severely contaminated refrigerant circuit (the refrigerant oil from the re‐ frigerant circuit is black and viscous or there is a lot of swarf in the refrigerant circuit), the filter is to be replaced. In the case of such severely contaminated refrigerant circuits it is also ap‐ propriate to flush the circuit again after replacing the filter.

♦

Depending on the nature of the impurities, dirt (used refriger‐ ant oil and abrasion from the air conditioner compressor) accumulates at the inspection port of the refrigerant circuit flushing attachment. If applicable, this inspection port is to be cleaned after flushing and the refrigerant circuit flushed again in one operation as a check (one operation is then sufficient).

♦

Liquid refrigerant cannot be routed at the necessary rate through the expansion valve, restrictor and desiccant bag of certain receivers. These components are therefore to be re‐ moved and replaced with adapters if applicable ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦

Adapters for connection of air conditioner service station and for bridging certain refrigerant circuit components

⇒ page 77 .

– Switch on the air conditioner service station and flush the re‐

frigerant circuit (duration approx. 1 to 1.5 hours for one flushing cycle with three flushing operations).

4. Refrigerant circuit 69

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Note

♦

The flushing operation is to be performed in line with the op‐ erating instructions for the air conditioner service station.

♦

Depending on the version of the air conditioner service station, the used oil container may only hold approx. 125 cm 3 of re‐

frigerant oil. If a system with a larger refrigerant oil quantity is to be flushed, it may be necessary to empty the used oil con‐ tainer after the first flushing operation in a flushing cycle.

♦

Observe the refrigerant flowing back out of the refrigerant cir‐ cuit into the air conditioner service station. Refrigerant circuit cleaning has not been completed until the refrigerant flowing through the inspection port of the refrigerant circuit flushing attachment into the air conditioner service station is clear and completely colourless.

♦

During flushing, the entire refrigerant oil is rinsed out of the refrigerant circuit (with the exception of slight residue in the evaporator, for example; this can however be ignored).

♦

In the case of extremely severe contamination, it may be nec‐ essary to perform flushing twice (two flushing cycles with three flushing operations each).

Sequence of flushing operation (sequence takes place automat‐ ically in line with air conditioner service station program)

♦ After switch-on, the flushing circuit (refrigerant circuit with con‐

necting hoses and refrigerant circuit flushing attachment) is initially evacuated and the refrigerant circuit checked for leaks (depending on the version of the air conditioner service sta‐ tion, manual switching to next step may be necessary).

♦ A specified quantity of refrigerant (e.g. 5 kg) is added to the

evacuated refrigerant circuit via the high-pressure end of the air conditioner service station (in the direction opposite to the normal flow direction during air conditioner operation and thus on the low-pressure end of the vehicle refrigerant circuit) or refrigerant is added until the refrigerant circuit and the inspec‐ tion ports of the refrigerant circuit flushing attachment have been completely filled with liquid refrigerant (depending on the version of the air conditioner service station, the system de‐ tects that there has been no further inflow of refrigerant over a certain period for example).

♦ Once the specified quantity of refrigerant has been added, the

heater of the refrigerant circuit flushing attachment may be switched on for example depending on the version of the air conditioner service station and the refrigerant circuit flushing attachment (only if the refrigerant is extracted in gaseous form from the refrigerant circuit flushing attachment).

♦ After the refrigerant has been extracted, the heater of the re‐

frigerant circuit flushing attachment is switched off (if fitted). Depending on the version, the refrigerant circuit may be briefly evacuated again and, following evacuation, the refrigerant oil extracted from the refrigerant circuit is separated by the air conditioner service station.

♦ The refrigerant charging, extraction (and evacuation) process

is repeated twice (in other words it is implemented a total of three times).

♦ Following extraction for the third time, the flushing circuit is

evacuated depending on the version of the air conditioner service station.

70 Rep. gr.87 - Air conditioning system

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Air conditioner with refrigerant R134a - Edition 01.2011

– On completion of flushing, check the inspection port(s) of the

refrigerant circuit flushing attachment. If these are contamina‐ ted, they are to be cleaned if necessary in line with the oper‐ ating instructions for the refrigerant circuit flushing attachment or air conditioner service station. Flushing is then to be per‐ formed again as a check (one operation with a duration of approx. 30 min. is sufficient).

– Check the pressure in the refrigerant circuit. There must not

be any positive pressure in the refrigerant circuit (evacuate briefly again if necessary).

– Detach the connections to the air conditioner service station

from the vehicle refrigerant circuit (there must not be any pos‐ itive pressure in the refrigerant circuit).

– Replace the vehicle-specific components (restrictor and res‐

ervoir, expansion valve and receiver or dryer cartridge in the receiver) ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue .

– Depending on the problem, replace the air conditioner com‐

pressor ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual) and ⇒ Electronic parts catalogue or drain off the remaining refrigerant oil from the air conditioner compressor removed

⇒ page 143 (replace refrigerant circuit components) and add

the specified quantity of fresh refrigerant oil again

⇒ page 174 (approved refrigerant oils and refrigerant oil ca‐

pacities).

Note

♦

Replacement compressors contain a certain specified quantity of refrigerant oil. For vehicles with two evaporators, it may be necessary to additionally add a certain quantity of refrigerant oil to the circuit ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop man‐ ual) and ⇒ page 174 (approved refrigerant oils and refrigerant oil capacities).

♦

If the air conditioner compressor is not to be replaced, the re‐ frigerant oil quantity in the air conditioner compressor must be topped up in line with the specified capacity (pour out refrig‐ erant oil and add the specified quantity to the air conditioner compressor or the refrigerant circuit again) ⇒ page 143 (re‐ placing refrigerant circuit components) and ⇒ page 174 (ap‐ proved refrigerant oils and refrigerant oil capacities).

– Completely re-assemble the refrigerant circuit ⇒ Heating, air

conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

– Evacuate and charge the refrigerant circuit as specified

⇒ page 54 and ⇒ page 58 .

– Start up the air conditioner as specified ⇒ Heating, air condi‐

tioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual) and ⇒ page 58 .

♦ Block diagrams for various flushing circuits ⇒ page 72

♦ Adapters for connecting up flushing circuits ⇒ page 77

4. Refrigerant circuit 71

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

4.5.1 Block diagrams for various flushing cir‐ cuits

Note

♦

The arrows in the following illustrations indicate the direction of refrigerant flow on flushing (during flushing, the refrigerant flows in the direction opposite to that in air conditioner opera‐ tion; the high-pressure end of the air conditioner service sta‐ tion is thus connected to the low-pressure connection of the refrigerant circuit to the air conditioner compressor).

♦

The block diagrams illustrate a refrigerant circuit with restrictor and reservoir and a refrigerant circuit with expansion valve, receiver and a second evaporator (optional extra for certain vehicles).

♦

Depending on the design of the air conditioner service station, non-return valves may be fitted between the refrigerant circuit and the air conditioner service station (to guarantee the correct direction of refrigerant flow on flushing).

Refrigerant circuit with restrictor and reservoir

Note

On vehicles with a restrictor and reservoir, the restrictor and res‐ ervoir are removed and the lines unfastened to remove the re‐ strictor are connected back together. The line connections to the reservoir removed are connected together with two adapters and the charging hose -VAS 6338/31- (from the VW/Audi passenger vehicle adapter set -VAS 6338/1- ).

72 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

1 - Air conditioner service sta‐ tion

❑ With electronics and a

flushing program, e.g. Air conditioner service station with flushing at‐ tachment ⇒ Workshop equipment and special tools catalogue

❑ If use is made of an air

conditioner service sta‐ tion with no flushing pro‐ gram, the process is to be implemented man‐ ually (evacuation, 3x flushing with at least 4 kg of refrigerant each time, extraction of refrig‐ erant again, evacua‐ tion).

2 - Refrigerant hose of air con‐ ditioner service station

❑ From the high-pressure

end of the air condition‐ er service station (gen‐ erally red coloured) to the connection for the low-pressure end of the air conditioner compres‐ sor at the refrigerant cir‐ cuit (larger diameter)

3 - Adapter for low-pressure end connection at refrigerant circuit

❑ Different versions de‐

pending on vehicle

⇒ page 77

❑ From VW/Audi passen‐

ger vehicle adapter set -VAS 6338/1-

4 - Low-pressure end connection at refrigerant circuit

❑ Different versions depending on vehicle ⇒ page 77 ❑ At the refrigerant line from the air conditioner compressor to the reservoir

5 - Connection to reservoir

❑ Different versions depending on vehicle ⇒ page 77 ❑ At the refrigerant line from the air conditioner compressor to the reservoir

6 - Adapter for bridging reservoir removed

❑ Different versions depending on vehicle ⇒ page 77 ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

7 - Refrigerant charging hose ⇒ page 77

❑ For example Charging hose -VAS 6338/31- (from VW/Audi passenger vehicle adapter set -VAS 6338/1- )

8 - Adapter for bridging reservoir removed

❑ Different versions depending on vehicle ⇒ page 77 ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

9 - Connection to reservoir

❑ Different versions depending on vehicle ⇒ page 77

4. Refrigerant circuit 73

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

10 - Evaporator

11 - Restrictor fitting location

❑ Restrictor removed ❑ Remove the restrictor ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-

specific workshop manual).

12 - Union in refrigerant line

❑ Screw back together following restrictor removal ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air

conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

13 - Condenser

14 - High-pressure end connection at refrigerant circuit

❑ Different versions depending on vehicle ⇒ page 77

15 - Adapter for high-pressure end connection at refrigerant circuit

❑ Different versions depending on vehicle ⇒ page 77 ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

16 - Charging hose to refrigerant circuit flushing attachment

❑ From the high-pressure end connection of the air conditioner compressor at the refrigerant circuit (smaller

diameter) to the inlet of the refrigerant circuit flushing attachment.

17 - Refrigerant circuit flushing attachment

❑ Different versions and different design of refrigerant circuit flushing attachment ⇒ Workshop equipment

and special tools catalogue ❑ With filter, inspection port, safety valve, heater, refrigerant vessel etc. (depending on version) ❑ Depending on the design of the air conditioner service station and the refrigerant circuit flushing attach‐

ment, a non-return valve may be fitted at the outlet of the refrigerant circuit flushing attachment (to

guarantee the correct direction of refrigerant flow on flushing).

18 - Refrigerant hose of air conditioner service station

❑ From low-pressure end of air conditioner service station (normally blue coloured) to outlet of refrigerant

circuit flushing attachment

Refrigerant circuit with expansion valve, receiver and second evaporator

Note

♦

This block diagram shows a refrigerant circuit with expansion valve, receiver and a second evaporator (optional extra for certain vehicles).

♦

On vehicles with expansion valve and receiver, the expansion valve is removed and replaced with an adapter. Depending on the vehicle, the receiver is also removed and the line connec‐ tions to the receiver are connected together using two adapt‐ ers and a charging hose.

♦

On vehicles with one evaporator only, the components as of item „16“ are not fitted or are not required.

74 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

1 - Air conditioner service sta‐

tion

❑ With electronics and

flushing program, Air conditioner service sta‐ tion with flushing attach‐ ment ⇒ Workshop equipment and special tools catalogue

❑ If use is made of an air

conditioner service sta‐ tion with no flushing pro‐ gram, the process is to be implemented man‐ ually (evacuation, 3x flushing with at least 4 kg of refrigerant each time, extraction of refrig‐ erant again, evacua‐ tion).

2 - Refrigerant hose of air con‐

ditioner service station

❑ From the high-pressure

end of the air condition‐ er service station (gen‐ erally red coloured) to the connection for the low-pressure end of the air conditioner compres‐ sor at the refrigerant cir‐ cuit (larger diameter)

3 - Adapter for low-pressure

end connection at refrigerant

circuit

❑ Different versions de‐

pending on vehicle

⇒ page 77

❑ From VW/Audi passen‐

ger vehicle adapter set -VAS 6338/1-

4 - Low-pressure end connection at refrigerant circuit

❑ Different versions depending on vehicle ⇒ page 77

5 - Adapter for expansion valve removed

❑ Different versions depending on vehicle ⇒ page 77 ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

6 - Evaporator

7 - Connection to receiver

❑ Different versions depending on vehicle ⇒ page 77 ❑ Not fitted on vehicles with a dryer cartridge in the receiver at the condenser or with a receiver installed

in the condenser ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehiclespecific workshop manual).

8 - Adapter for bridging receiver removed

❑ Not necessary on all vehicles ❑ Different versions depending on vehicle ⇒ page 77 ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

9 - Refrigerant charging hose ⇒ page 77

❑ For example Charging hose -VAS 6338/31- (from VW/Audi passenger vehicle adapter set -VAS 6338/1- )

4. Refrigerant circuit 75

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

10 - Condenser

❑ If a receiver with dryer cartridge is fitted at the condenser, the dryer cartridge must be removed (seal

receiver at or in condenser again following removal) ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air

conditioning; Rep. gr. 87 vehicle-specific workshop manual). ❑ If the receiver is attached directly to the condenser, the receiver is only to be removed and replaced after

flushing ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific

workshop manual).

Note

11 - High-pressure end connection at refrigerant circuit

❑ Different versions depending on vehicle ⇒ page 77

12 - Adapter for high-pressure end connection at refrigerant circuit

❑ Different versions depending on vehicle ⇒ page 77 ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

13 - Charging hose to refrigerant circuit flushing attachment

❑ From the high-pressure end connection of the air conditioner compressor at the refrigerant circuit (smaller

diameter) to the inlet of the refrigerant circuit flushing attachment.

14 - Refrigerant circuit flushing attachment

❑ Different versions and different design of refrigerant circuit flushing attachment ⇒ Workshop equipment

and special tools catalogue ❑ With filter, inspection port, safety valve, heater, refrigerant vessel etc. (depending on version) ❑ Depending on the design of the air conditioner service station and the refrigerant circuit flushing attach‐

ment, a non-return valve may be fitted at the outlet of the refrigerant circuit flushing attachment (to

guarantee the correct direction of refrigerant flow on flushing).

15 - Refrigerant hose of air conditioner service station

❑ From low-pressure end of air conditioner service station (normally blue coloured) to outlet of refrigerant

circuit flushing attachment

16 - Adapter for sealing outlet to second evaporator

❑ Only required for certain vehicles with „second evaporator“ as optional extra ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

17 - Adapter for sealing outlet to second evaporator

❑ Only required for certain vehicles with „second evaporator“ as optional extra ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

18 - Low-pressure end connection at refrigerant circuit to second evaporator

❑ Different versions depending on vehicle

⇒ page 77

❑ Only fitted on certain vehicles with „second evaporator“ as optional extra

19 - High-pressure end connection at refrigerant circuit to second evaporator

❑ Different versions depending on vehicle ⇒ page 77 ❑ Only fitted on certain vehicles with „second evaporator“ as optional extra

20 - Adapter for expansion valve removed at second evaporator

❑ Different versions depending on vehicle ⇒ page 77 ❑ Only required for certain vehicles with „second evaporator“ as optional extra ❑ From VW/Audi passenger vehicle adapter set -VAS 6338/1-

21 - Second evaporator

❑ Only fitted on certain vehicles with „second evaporator“ as optional extra

76 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

4.5.2 Adapters for connecting up flushing cir‐ cuits

♦ The following table lists the various adapters required for con‐

necting the air conditioner service station to the refrigerant circuit for flushing and for bridging the removed receiver or reservoir and expansion valve (vehicle-specific).

♦ Use a charging hose with 5/8 - 18 UNF connections (short

version e.g. charging hose -VAS 6338/31- ) to connect the two adapters fitted in place of the reservoir or receiver removed (contained in VW/Audi passenger vehicle adapter set -VAS 6338/1- ).

♦ If a flushed refrigerant circuit is not to be re-assembled imme‐

diately after flushing, leave the adapters in place at the con‐ nections and seal the connections at the adapters with the caps -VAS 6338/30- (from the VW/Audi passenger vehicle adapter set -VAS 6338/1- ).

♦ Depending on the version of the air conditioner compressor

and the production period, use may have been made of dif‐ ferent connection and sealing methods at the refrigerant circuit ⇒ Heating, air conditioning; Rep. gr. 87 or ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦ The logo of the compressor manufacturer „Zexel“ affixed to the

air conditioner compressor was switched as of year of pro‐ duction 2006 (when the manufacturer's name changed) from „Zexel“ to the new name „Valeo“.

Block or screw connections

– Screw connection -A-

– Block connection -B-

Block connections with different types of seal

4. Refrigerant circuit 77

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

– Block connection with radial seal -A- (with plastic or metal

guide -B-)

– Block connection with axial seal -C-

Audi A1 and Audi A2

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi A1 (8X_) 2011 ►

– Compressor

manufacturer „Denso“, „Sanden“ or „Delphi“

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3- or Adapter -VAS 6338/2- (de‐ pending on the design of the air condi‐ tioner com‐ pressor and the corre‐ sponding re‐ frigerant line)

Adapters required for reservoir/receiver con‐ nections

Different versions – Version 1 (integra‐

ted receiver at con‐ denser): No adapt‐ er required, the desiccant bag is re‐ moved from the re‐ ceiver at the con‐ denser and the opening sealed off again for flushing.

Other re‐ quire‐ ments

Expansion valve re‐ moved and adapter VAS 6338/34fitted (or old expan‐ sion valve removed drilled open for

– Version 2 (receiver

attached to con‐ denser): No adapt‐ er required, the re‐

flushing and re-in‐ stalled)

⇒ page 67

ceiver is left in position (replaced after flushing)

Audi A2 (8Z_) 2001 ►

– Compressor

manufacturer „Denso“

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end

Reservoir – Screw connection

at inlet Adapter VAS 6338/9-

– Block connection

with axial seal at outlet Adapter VAS 6338/10-

- Restrictor

removed,

line con‐

nections

re-assem‐

bled

Adapter -VAS 6338/2-

Note

On the Audi A1, the receiver may be attached or integrated de‐ pending on the version of the condenser. The integrated receiver is fitted with a dryer cartridge which can be replaced separately. If the receiver is of the attached type (introduction not yet final‐ ised), it must be replaced after flushing ⇒ Electronic parts cata‐ logue and ⇒ Heating, air conditioning; Rep. gr. 87 .

78 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi A3 and Audi TT

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi A3 (8L_) 1997 ► Audi TT (8N_) 1999 ►

– Compressor

manufacturer „Sanden“ or „Zexel / Va‐ leo“

♦ Low-pres‐

sure end Adapter -VAS 6338/7-

♦ High-pres‐

sure end Adapter -VAS 6338/2-

Audi A3 (8P_) 2004 ► Audi TT (8J_) 2007 ►

– Compressor

manufacturer for Audi A3 „Sanden“, „Denso“, „Delphi“ or „Zexel / Va‐ leo“

– Compressor

manufacturer for Audi TT „Denso“

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Adapters required for reservoir/receiver con‐ nections

Receiver – Block connections

with axial seal at in‐ let and outlet Adapter -VAS 6338/2- (2x re‐ quired)

Receiver (different ver‐ sions) – Adapter not re‐

quired, receiver re‐ mains in position

– Depending on the

version of the con‐ denser, it may be necessary to re‐ move the dryer car‐ tridge from the re‐ ceiver at the con‐ denser before flushing and to seal the opening again (refer to note).

Other re‐ quire‐ ments

Expansion valve re‐ moved and Adapter VAS 6338/19fitted (or drilledopen ex‐ pansion valve e.g. 6N0 820 679 C fit‐ ted

⇒ page 67 )

Expansion valve re‐ moved and Adapter VAS 6338/18(or drilledopen ex‐ pansion valve e.g. 1K0 820

679) fitted

⇒ page 67

Note

♦

The design of the receiver on the Audi A3 and Audi TT differs depending on the condenser manufacturer. The Audi TT with 5-cyl. engine is fitted for example with a different type of con‐ denser to vehicles with a 4 or 6-cyl. engine. This condenser features an integrated receiver for example. The integrated receiver contains a dryer cartridge which is currently not al‐ ways available as a replacement part. On vehicles fitted with this condenser, it may therefore be necessary to replace the entire condenser after rectifying any problems ⇒ Electronic parts catalogue and ⇒ Heating, air conditioning; Rep. gr. 87 .

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately or which are not available separately, the condenser is to be replaced after flushing (together with the built-in dryer cartridge) ⇒ Heating, air conditioning; Rep. gr. 87 and ⇒ Electronic parts catalogue .

4. Refrigerant circuit 79

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Audi 80, Audi 90, Audi Coupé, Audi Cabriolet and Audi A4

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi 80 (8A_/ 8C_), Audi Coupé (8B_), Audi Cabrio‐ let (8G_) ► 2002 Audi A4 (8D_) 1995►

– Compressor

manufacturer „Zexel / Valeo“ (screw connections)

♦ Low-pres‐

sure end Adapter VAG 1785/8-

♦ High-pres‐

sure end Adapter VAG 1785/7-

– Compressor

manufacturer „Denso“ (bloc k connections with radial and axial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/2-

Audi A4 (8E_) 2001 ► Audi A4 Cabrio‐ let (8H_) 2003 ►

– Compressor

manufacturer „Denso“ (bloc k connections with radial and axial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/2-

Adapters required for reservoir connections

Other re‐

quire‐

ments

Reservoir with differ‐ ent connection ver‐ sions ♦ Version „1“

– Screw connection

at inlet Adapter -

- Restrictor

removed,

line con‐

nections

re-assem‐

bled

VAS 6338/9-

– Screw connection

at outlet Adapter VAG 1785/8-

♦ Version „2“

– Screw connection

at inlet Adapter VAS 6338/9-

– Block connection

with axial seal at outlet Adapter VAS 6338/10-

Reservoir with differ‐ ent connection ver‐ sions ♦ Version „1“

– Block connections

with axial seal at in‐

- Restrictor

removed,

line con‐

nections

re-assem‐

bled

let and outlet

♦ Adapter -VAS

6338/10- (2x re‐ quired)

80 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to

Adapters required for reservoir connections

Other re‐ quire‐

ments the air condition‐ er compressor

– Compressor

manufacturer „Denso“ (bloc k connections with radial seal) ⇒ Air conditioning; Rep. gr. 87

♦ Version „2“

– Block connections

with radial seal at inlet and outlet

♦ Adapter -VAS

6338/8- (2x re‐ quired)

(vehicle-spe‐ cific work‐ shop manual)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Audi A4 (8K_) 2008 ►

– Compressor

manufacturer „Denso“

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Receiver (different ver‐ sions) – Adapter not re‐

quired, receiver re‐ mains in position

– Depending on the

version of the con‐ denser, it may be necessary to re‐ move the dryer car‐ tridge from the re‐ ceiver at the con‐ denser before flushing and to seal

Expansion

valve re‐

moved and

Adapter -

VAS

6338/36-

(or drilled-

open ex‐

pansion

valve e.g.

8K0 820

679 A) fit‐

ted

⇒ page 67

– The re‐

the opening again (refer to note).

friger‐ ant line with in‐ ternal heat ex‐ chang‐ er re‐ mains in posi‐ tion or is in‐ stalled again after fit‐ ting the adapt‐ er.

4. Refrigerant circuit 81

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

The design of the receiver on the Audi A4 (8K_) 2008 > differs depending on the condenser manufacturer ⇒ Air conditioning; Rep. gr. 87 . The receiver may be attached or integrated de‐ pending on the version of the condenser. The integrated re‐ ceiver contains a dryer cartridge which is currently not always available as a replacement part. On vehicles fitted with this condenser, it may therefore be necessary to replace the entire condenser after rectifying any problems ⇒ Electronic parts catalogue .

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately or which are not available separately, the condenser is to be replaced after flushing (together with the built-in dryer cartridge) ⇒ Heating, air conditioning; Rep. gr. 87 and ⇒ Electronic parts catalogue .

Audi A5 Coupé and Sportback, Audi Q5, Audi A5 Cabriolet

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi A5 Coupé and Sport‐ back (8T_) 2008 ► Audi Q5 (8R_) 2008 ► Audi A5 Cabrio‐ let (8F_) 2009 ►

– Compressor

manufacturer „Denso“

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Adapters required for receiver connections

Receiver (different ver‐ sions) – Adapter not re‐

quired, receiver re‐ mains in position

– Depending on the

version of the con‐ denser, it may be necessary to re‐ move the dryer car‐ tridge from the re‐ ceiver at the con‐ denser before flushing and to seal the opening again (refer to note).

Other re‐ quire‐ ments

Expansion valve re‐ moved and Adapter VAS 6338/36(or drilledopen ex‐ pansion valve e.g. 8K0 820 679 A) fit‐ ted

⇒ page 67

– The re‐

friger‐ ant line with in‐ ternal heat ex‐ chang‐ er re‐ mains in posi‐ tion or is in‐ stalled again after fit‐ ting the adapt‐ er.

82 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

The design of the receiver differs on these vehicles depending on the condenser manufacturer ⇒ Air conditioning; Rep. gr. 87 . The receiver may be attached or integrated depending on the version of the condenser. The integrated receiver contains a dryer cartridge which is currently not always available as a replacement part. On vehicles fitted with this condenser, it may therefore be necessary to replace the entire condenser after rectifying any problems ⇒ Electronic parts catalogue .

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately or which are not available separately, the condenser is to be replaced after flushing (together with the built-in dryer cartridge) ⇒ Heating, air conditioning; Rep. gr. 87 and ⇒ Electronic parts catalogue .

4. Refrigerant circuit 83

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Audi 100, Audi A6 (4A_, 4B_ and 4F_), Audi allroad and Audi V8

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi 100 / Audi A6 (4A_) ► 1998 Audi A6 (4B_) 1998 ► Audi all‐ road (4B_) ► 2005 Audi V8 (4C_) ►

– Compressor

manufacturer „Zexel / Valeo“ (screw connections)

♦ Low-pres‐

sure end Adapter VAG 1785/8-

♦ High-pres‐

sure end Adapter VAG 1785/7-

1994

– Compressor

manufacturer „Denso“ (bloc k connections with radial and axial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/2-

Audi A6 (4F_) 2005 ►

– Compressor

manufacturer „Denso“ (bloc k connections with radial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Adapters required for reservoir connections

Other re‐ quire‐ ments

Reservoir with differ‐ ent connection ver‐ sions ♦ Version „1“

– Screw connection

at inlet Adapter -

- Restrictor removed, line con‐ nections re-assem‐ bled

VAS 6338/9-

– Screw connection

at outlet Adapter VAG 1785/8-

♦ Version „2“

– Screw connection

at inlet Adapter VAS 6338/9-

– Block connection

with axial seal at outlet Adapter VAS 6338/10-

♦ Version „3“

– Block connections

with axial seal at in‐ let and outlet Adapter -VAS 6338/10- (2x re‐ quired)

– Reservoir with

block connections with radial seal at inlet and outlet

♦ Adapter -VAS

6338/8- (2x re‐

- Restrictor removed, line con‐ nections re-assem‐ bled

quired)

Note

The specifications for the Audi A6 (4F_) 2005 ► also apply to the Audi S6 and Audi RS6.

84 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Audi A6 (4G_), Audi A7 (4G_)

Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to

Adapters required for receiver connections

Other re‐

quire‐

ments the air condition‐ er compressor

Audi A6 (4G_) 2011 ► Audi A7 (4G_) 2011 ►

– Compressor

manufacturer „Denso“

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Receiver (different ver‐ sions) – Adapter not re‐

quired, receiver re‐ mains in position

– Depending on the

version of the con‐ denser, it may be necessary to re‐ move the dryer car‐ tridge from the re‐ ceiver at the con‐ denser before flushing and to seal the opening again (refer to note).

Expansion

valve re‐

moved and

adapter -

VAS

6338/36-

fitted (or

old expan‐

sion valve

removed

drilled

open for

flushing

and re-in‐

stalled

⇒

page 67 ).

Note

♦

The design of the receiver differs on these vehicles depending on the condenser manufacturer ⇒ Air conditioning; Rep. gr. 87 and ⇒ Electronic parts catalogue .

♦

In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately or which are not available separately, the condenser is to be replaced after flushing (together with the built-in dryer cartridge) ⇒ Air con‐ ditioning; Rep. gr. 87 and ⇒ Electronic parts catalogue .

4. Refrigerant circuit 85

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi A8

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi A8 (4D_) 1994 ►

– Compressor

manufacturer „Zexel / Valeo“ (screw connections)

♦ Low-pres‐

sure end Adapter VAG 1785/8-

♦ High-pres‐

sure end Adapter VAG 1785/7-

– Compressor

manufacturer „Denso“ (bloc k connections with radial and axial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/2-

Audi A8 (4E_) 2003 ►

– Compressor

manufacturer „Denso“ (bloc k connections with radial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

Adapters required for reservoir connections

Other re‐ quire‐ ments

Reservoir with differ‐ ent connection ver‐ sions ♦ Version „1“

– Screw connection

at inlet Adapter -

- Restrictor removed, line con‐ nections re-assem‐ bled

VAS 6338/9-

– Screw connection

at outlet Adapter VAG 1785/8-

♦ Version „2“

– Screw connection

at inlet Adapter VAS 6338/9-

– Block connection

with axial seal at outlet Adapter VAS 6338/10-

♦ Version „3“

– Block connections

with axial seal at in‐ let and outlet Adapter -VAS 6338/10- (2x re‐ quired)

Reservoir – Block connections

with radial seal at inlet and outlet

♦ Adapter -VAS

6338/8- (2x re‐

- Restrictor removed, line con‐ nections re-assem‐ bled

quired)

86 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi A8 (4H_) 2010 ►

– Compressor

manufacturer „Denso“ (bloc k connections with radial seal)

♦ Low-pres‐

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

♦ Addi‐

tio‐ nally for vehi‐ cles with 2 evap‐ ora‐ tors (4zone air con‐ di‐ tio‐ ner)

Adapters required for reservoir connections

– No adapter re‐

quired, the desic‐ cant bag is re‐ moved from the receiver at the con‐ denser and the opening sealed off again for flushing.

For flushing the circuit with the evaporator in the front air condition‐ ing unit ♦ Adapter -VAS

6338/5- for sealing the „low-pressure end“ connection (to the second evapo‐ rator)

♦ Adapter -VAS

6338/11- for seal‐ ing the „high-pres‐ sure end“ connec‐ tion (to the second evaporator)

• An additional hole may have to be made in the adapt‐ ers (see below) to be able to seal the refrigerant lines with the adapters VAS 6338/5- and VAS 6338/11-

Other re‐ quire‐ ments

Expansion valve re‐ moved and adapter VAS 6338/18fitted (or old expan‐ sion valve removed drilled open for flushing and re-in‐ stalled

⇒ page 67 ).

4. Refrigerant circuit 87

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Adapters required for reservoir connections

For flushing the sec‐ ond evaporator and the corresponding lines ♦ Adapter -VAS

6338/3- for con‐ necting the air con‐ ditioner service sta‐ tion to the „lowpressure end“ con‐ nection (to the sec‐ ond evaporator).

♦ Adapter -VAS

6338/4- for con‐ necting the air con‐ ditioner service sta‐ tion to the „highpressure end“ con‐ nection (to the sec‐ ond evaporator).

• The adapter may have to be re‐ worked (see below) to be able to con‐ nect the refrigerant line to the adapter VAS 6338/3-

Other re‐ quire‐ ments

Expansion valve in re‐ frigerant lines to second evaporator removed and adapt‐ er -VAS 6338/18fitted (or old expan‐ sion valve removed drilled open for flushing and re-in‐ stalled

⇒ page 67 ).

Note

♦

On vehicles with two evaporators, the refrigerant circuit is flushed in two operations.

♦

At present the front and rear expansion valves have identical connections (only the control characteristic differs).

Making additional hole in adapters -VAS 6338/5- and -VAS 6338/11-

– Make a hole -A- in addition to the hole provided (the dimen‐

sions in the illustration are given in mm).

Reworking adapter -VAS 6338/3-

88 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

– By grinding or filing off material in area -A-, rework the adapter

-VAS 6338/3- such that it can be connected without bending the refrigerant line (the dimensions in the illustration are given in mm).

4. Refrigerant circuit 89

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi Q7

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Audi Q7 (4L_) 2006 ► ♦ Vehi‐

– Compressor

cle with one

♦ Low-pres‐ evap‐ ora‐ tor (2-

♦ High-pres‐

zone air con‐ di‐

manufacturer „Denso“ (bloc k connections with radial seal)

sure end Adapter -VAS 6338/12-

sure end Adapter -VAS 6338/3-

tio‐ ner)

♦ Addi‐

tio‐ nally for vehi‐ cles with 2 evap‐ ora‐ tors (4zone air con‐ di‐ tio‐ ner)

Adapters required for connections to receiv‐ er / to second evapo‐

Other re‐ quire‐ ments

rator

– No adapter re‐

quired, the dryer is removed from the receiver at the con‐ denser and the opening sealed off again.

Expansion valve re‐ moved and adapter VAS 6338/17or adapter

-VAS 6338/33fitted de‐ pending on version of expansion valve (or drilledopen ex‐ pansion valve e.g. 7L0 820 712 A, 7H0 820 679 B or 7L0 820 679 C fit‐ ted

⇒ page 67 )

⇒ Elec‐ tronic parts catalogue .

For flushing the circuit with the evaporator in the front air condition‐ ing unit ♦ Adapter -VAS

6338/5- for sealing the „low-pressure end“ connection (to the second evapo‐ rator)

♦ Adapter -VAS

6338/11- for seal‐ ing the „high-pres‐ sure end“ connec‐ tion (to the second evaporator)

90 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Vehicle Adapters re‐

quired for the connections to the air condition‐ er compressor

Adapters required for connections to receiv‐ er / to second evapo‐ rator

For flushing the sec‐ ond evaporator and the corresponding lines ♦ Adapter -VAS

6338/3- for con‐ necting the air con‐ ditioner service sta‐ tion to the „lowpressure end“ con‐ nection (to the sec‐ ond evaporator).

♦ Adapter -VAS

6338/4- for con‐ necting the air con‐ ditioner service sta‐ tion to the „highpressure end“ con‐ nection (to the sec‐ ond evaporator).

Other re‐ quire‐ ments

Expansion valve at second evaporator removed and Adapt‐ er -VAS 6338/17fitted (or drilledopen ex‐ pansion valve e.g. 7L0 820 712 A fitted

⇒ page 67 )

⇒ Elec‐ tronic parts catalogue

Note

On vehicles with two evaporators, the refrigerant circuit is flushed in two operations.

Audi R8

Vehicle Adapters re‐

quired for the connections to

Adapters required for reservoir connections

Other re‐ quire‐

ments the air condition‐ er compressor

Audi R8 (42_) 2008 ►

– Compressor

manufacturer „Denso“ (bloc k connections with radial seal)

♦ Low-pres‐

Reservoir – Block connections

with radial seal at inlet and outlet

♦ Adapter -VAS

6338/8- (2x re‐ quired)

- Restrictor

removed,

line con‐

nections

re-assem‐

bled

sure end Adapter -VAS 6338/12-

♦ High-pres‐

sure end Adapter -VAS 6338/3-

4. Refrigerant circuit 91

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Note

♦

On the Audi R8, the engine must be removed to replace the air conditioner compressor. For flushing the refrigerant circuit, the refrigerant lines can however be detached without remov‐ ing the air conditioner compressor ⇒ Air conditioning; Rep. gr. 87 (vehicle-specific workshop manual).

♦

The two condensers are flushed in situ in the direction oppo‐ site to that of the refrigerant flow.

4.6 Determining refrigerant circuit leaks

Vehicles with start/stop system

WARNING

Risk of injury due to automatic starting of engine on vehicles with a start/stop system.

♦ The engine may start automatically if required on vehicles

with an activated start/stop system (indicated in the dash panel insert).

♦ When working on the vehicle it should thus be ensured

that the start/stop system has been deactivated (switch off ignition, switch on again if necessary).

All vehicles

Note

♦

Minor leaks can be detected with an electronic leak detector or UV leak detector lamp for example.

♦

This Workshop Manual describes refrigerant circuit leak de‐ tection using two different methods. These methods have been checked and yield reliable results under various usage conditions if implemented properly and on a problem-related basis.

♦

There are numerous systems available on the market for the detection of refrigerant circuit leaks. Not all of these yield un‐ equivocable results and, if not employed in the specified man‐ ner, may indicate leaks at various refrigerant circuit compo‐ nents although these are actually intact. In addition, certain methods may cause damage to or impair refrigerant circuit components.

♦ Components found to be leaking are to be replaced and not

repaired.

♦ Leaking refrigerant circuits are not to be filled with refrigerant.

Empty refrigerant circuits are therefore to be evacuated before filling with refrigerant and checked for leaks in this process

⇒ page 54 .

92 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

Caution

♦ Audi does not permit the use of chemical substances

(sealing additives) to seal leaks in the refrigerant circuit.

♦ Chemical substances for sealing leaks form deposits in

the refrigerant circuit which will impair operation of the air conditioning system and lead to failure of the system (and of the air conditioner service station).

Note

Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit generally react with the ambient air or the hu‐ midity contained in it. They cause malfunctioning of valves and other components with which they come into contact on account of deposits in the refrigerant circuit (and in the air conditioner service station being used). These deposits cannot be completely removed from the components (even by flushing). The refrigerant circuit can therefore only be repaired by replacing all the compo‐ nents which have come into contact with this substance.

♦ ⇒ „4.6.1 Tracing refrigerant circuit leaks with electronic leak

detector (e.g. V.A.G 1796)“, page 93 .

♦ ⇒ „4.6.2 Locating refrigerant circuit leaks with leak detection

system VAS 6201“, page 95 .

4.6.1 Tracing refrigerant circuit leaks with electronic leak detector (e.g. V.A.G

1796)

Caution

Proceed as follows with a completely empty refrigerant circuit to avoid allowing more refrigerant than is absolutely necessary for leak detection to escape into the environment:

– Evacuate the refrigerant circuit using the air conditioner serv‐

ice station ⇒ page 54 .

Note

♦

If evacuation already reveals a major leak, this is to be located and eliminated as described ⇒ page 54 .

♦

Continue as follows if evacuation does not reveal any leakage or if the leakage is so slight that it is not possible to determine the leakage location.

– Pour roughly 100 g of refrigerant into the evacuated refrigerant

circuit.

Leak detection:

– Start up the leak detector in line with the operating instructions.

4. Refrigerant circuit 93

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

– Always hold the probe tip under the location of the suspected

leak.

If the clicking rate increases or a warning tone sounds (depends on model), this indicates that the leak has been located (refer to operating instructions for leak detector).

Note

♦

Refrigerant gas is quickly dispersed by the movement of air. Draughts must therefore be avoided during leak detection.

♦

Refrigerant gas is heavier than air and therefore sinks to a lower level at the exit location.

94 Rep. gr.87 - Air conditioning system

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...

Air conditioner with refrigerant R134a - Edition 01.2011

4.6.2 Locating refrigerant circuit leaks with leak detection system VAS 6201

Note

♦

Certain leaks are difficult or even impossible to locate using an electr. leak detector. In such cases, use can be made of the leak detection system VAS 6201.

♦

Refrigerant circuit leaks result in a loss of refrigerant oil to‐ gether with the refrigerant. This oil generally remains in the vicinity of the leak location. Adding a small quantity of fluores‐ cent fluid to the refrigerant circuit makes this oil visible under UV light. The fluid (PAG oil containing an additive which shows up under UV light) is poured into the refrigerant circuit and becomes distributed with the refrigerant oil when the air con‐ ditioner is switched on.

♦

The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (the air conditioner compressor must run). Depending on the extent of the leak, the leakage location may already become visible un‐ der UV light within this period.

♦

The refrigerant oil containing the additive (which shows up un‐ der UV light) can either be poured directly into the open circuit or pumped in with the circuit charged using the hand pump VAS 6201/1 (from the leak detection system VAS 6201) via the service connection on the low-pressure end.

♦

If the leak detection additive is applied via the service con‐ nection on the low-pressure end with the refrigerant circuit charged, a small quantity of additive remains in the service connection. This is to be carefully removed so as to avoid subsequent erroneous leak detection.

♦

If a component forming part of a circuit into which the leak detection additive is poured has to be replaced, thoroughly clean the joints with the other components after assembling the refrigerant circuit. Otherwise, the residual leak detection additive at the joint could be erroneously identified as a leak‐ age location during subsequent leak localisation.

♦

On discharging the refrigerant circuit, refrigerant oil and thus also leak detection additive ingresses into the air conditioner service station. The refrigerant oil is removed from the refrig‐ erant in the oil separator of the air conditioner service station and discharged from the air conditioner service station via the drain. The refrigerant oil drained off is not to be poured back in. It is to be replaced with fresh refrigerant oil.

♦

Heed the following if leak detection fluid has already been poured into a refrigerant circuit in the course of previous repair work: Only pour in fresh leak detection fluid if the refrigerant oil is replaced. If only a certain amount of refrigerant oil has been replaced, just add the corresponding quantity of leak de‐ tection fluid. After replacing 100 ml of refrigerant oil on a

vehicle containing 250 ml for example, just add 1 ml (cm3) of leak detection additive.

♦

Certain materials and their compounds (e.g. oxidation prod‐ ucts on aluminium components, anti-corrosion waxes) also show up under UV light.

♦

Certain types of air conditioner service station permit the direct introduction of the leak detection additive (heed the informa‐ tion given in the operating instructions of the air conditioner service station).

4. Refrigerant circuit 95

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by AUDI AG.

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ... Air conditioner with refrigerant R134a - Edition 01.2011

Proceed as follows with a completely empty refrigerant circuit to avoid allowing more refrigerant than is absolutely necessary for leak detection to escape into the environment when localising re‐ frigerant circuit leaks:

– Evacuate the refrigerant circuit using the air conditioner serv‐

ice station ⇒ page 54 .

Note

♦

If evacuation already reveals a major leak, this is to be located and eliminated as described ⇒ page 54 .

♦

Continue as follows if evacuation does not reveal any leakage or if the leakage is so slight that it is not possible to determine the leakage location.

For leakage which cannot be determined by way of evacuation, refer to ⇒ page 96 .

Tools and other items required:

1 - Hand pump with low-pressure service hose, service cou‐

pling and non-return valve -VAS 6201/1-

2 - Cartridge -VAS 6201/2-

3 - Cleaning agents -VAS 6201/3-

4 - UV leak detection lamp -VAS 6201/4-

5 - UV-absorbing safety goggles -VAS 6201/6-

6 - Sticker -VAS 6201/7-

7 - Tube

VAS 6201/8

8 - Protective gloves -VAS 6201/9-

Pouring in leak detection additive with refrigerant circuit empty

The cartridge -A- contains 15.4 ml of leak detection additive (one unit -B- corresponds to 2.5 ml).

96 Rep. gr.87 - Air conditioning system

Audi TT 24 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1.1 General information

1.2 Introduction

1. General information on air conditioning systems 1

1.3 Safety precautions for vehicles with a start/stop system

1.4 Other reference material

1.5 Basics of air conditioning technology

1.5.1 Physical principles:

1.5.2 Pressure and boiling point

1.5.3 Vapour pressure table for refrigerant R134a

1.6 Refrigerant R134a

1.6.1 Physical data of refrigerant R134a

1.6.2 Critical point

1.6.3 Environmental aspects of refrigerant R134a

1.7 Properties of refrigerant R134a

1.7.1 Trade names and designations

1.7.2 Colour

1.7.3 Vapour pressure

1.7.4 Physical properties of R134a

1.7.5 Effects on metal

1.7.6 Critical temperature / critical pressure

1.7.7 Water content

1.7.8 Combustibility

1.7.9 Charge factor

1.7.10 Detecting leaks

1.8 Refrigerant oil

1.8.1 Properties of refrigerant oil

1.9 How air conditioning works

1.9.1 Comfort

1.9.2 Environmental aspects

1.10 General work safety

1.11 Product properties

1.12 Handling refrigerant

1.13 Handling pressure vessels

1.16 Basics for working on refrigerant circuit

1.16.1 General

1.16.2 Cleaning refrigerant circuit

1.16.4 O-rings

2.1 Refrigerant circuit components

2.2 Arrangement of the refrigerant circuit components and their influence on the high and low-pressure ends

2.2.1 Air conditioner compressor

2.2.2 Condenser

2.2.3 Evaporator

2.2.4 Reservoir

2.2.5 Restrictor

2.2.6 Receiver

2.2.7 Expansion valve

2.2.9 Refrigerant line quick-release coupling connections

2.2.10 O-rings

2.2.11 Pipes and hoses of refrigerant circuit

2.2.12 Pressure relief valve

2.3 Design of refrigerant circuit

2.4 Quick-release coupling connections in refrigerant circuit

2.4.2 Connections with primary sealing valve (ball valve)

2.5.4 Connections with valve for switches in refrigerant circuit

2.5.6 High-pressure sender -G65-

2.5.7 Refrigerant pressure and temperature sender -G395-

2.5.8 Air conditioner compressor regulating valve -N280-

2.6 Electrical components not installed in refrigerant circuit

2.6.1 Radiator fan control unit -J293-

2.7.1 Refrigerant circuit with expansion valve

2.7.2 Refrigerant circuit with restrictor and reservoir

2.8 Test and measurement operations which can be performed with a pressure gauge

2.8.1 Pressure gauges permit the following test and measurement operations

2.9 Air conditioner service and recycling units

2.9.1 Classification of extraction systems

2.9.2 Charging systems not requiring a permit

2.10 Repair information for refrigerant circuit

3 Laws and regulations

3.1 Laws and regulations

3.1.2 Maintaining records on refrigerant

4 Refrigerant circuit

4.2 Converting refrigerant circuits from R12 refrigerant to R134a

4.3 Working with the air conditioner service station

4.3.1 Important notes for working with the air conditioner service station

4.3.3 Discharging refrigerant circuit with air conditioner service station

4.3.4 Evacuating refrigerant circuit with air conditioner service station