audi Aire acondicionado Aire acondicionado

Service

Workshop Manual

Audi 100 1991 ➤ , Audi 80 1992 ➤ ,

Audi A1 2011 ➤ , Audi A1 Sportback 2018 ➤ , Audi A2 2001 ➤ , Audi A3 1997 ➤ , Audi A3 2004 ➤ , Audi A3 2013 ➤ , Audi A3 Cabriolet 2015 ➤ , Audi A3 Limousine 2014 ➤ , Audi A3 Limousine China 2014 ➤ , Audi A3 Sportback 2013 ➤ , Audi A3 Sportback China 2014 ➤ , Audi A4 1995 ➤ , Audi A4 2001 ➤ , Audi A4 2008 ➤ , Audi A4 2015 ➤ , Audi A4 Avant 2015 ➤ , Audi A4 Cabriolet 2003 ➤ , Audi A4 China 2016 ➤ , Audi A4 allroad quattro 2016 ➤ , Audi A5 2016 ➤ , 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 A6 2019 ➤ , Audi A6 China 2012 ➤ , Audi A6 China 2019 ➤ , Audi A7 Sportback 2011 ➤ , Audi A7 Sportback 2018 ➤ , Audi A8 1994 ➤ , Audi A8 2003 ➤ , Audi A8 2010 ➤ , Audi A8 2018 ➤ , Audi Cabriolet 1991 ➤ , Audi Q2 2016 ➤ , Audi Q2 China 2019 ➤ , Audi Q3 2012 ➤ ,

Service Department. Technical Information

Service

Audi Q3 2019 ➤ , Audi Q3 China 2013 ➤ , Audi Q3 China 2019 ➤ , Audi Q5 2008 ➤ , Audi Q5 2017 ➤ , Audi Q5 China 2010 ➤ , Audi Q5 China 2019 ➤ , Audi Q7 2007 ➤ , Audi Q7 2016 ➤ , Audi Q8 2018 ➤ , Audi R8 2007 ➤ , Audi R8 2015 ➤ , Audi TT 1999 ➤ , Audi TT 2007 ➤ , Audi TT 2015 ➤ , Audi e-tron 2019 ➤

Air conditioner with refrigerant R134a

Edition 05.2019

Service Department. Technical Information

List of Workshop Manual Repair Groups

Re pa ir G ro up

87 - Air conditioning system

Service

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.

Service

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Contents

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

1 Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Safety precautions when working on air conditioners . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Safety precautions when handling refrigerants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Safety precautions when working on vehicles with start/stop system . . . . . . . . . . . . . . . . 2

1.4 Safety precautions when working on vehicles with high-voltage system . . . . . . . . . . . . . . 2

1.5 Safety precautions when working in the vicinity of high-voltage components . . . . . . . . . . 3

1.6 Safety precautions when using testers and measuring instruments during a road test . . . . 4

2 General information on air conditioning systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Other reference material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3 Principles of air conditioning systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.4 Refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.5 Properties of refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.6 Refrigerant oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.7 How air conditioning works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.8 General work safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.9 Product properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.10 Handling refrigerant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.11 Handling pressure vessels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.12 Basic rules for working on refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.13 Before using air conditioner after system has been re-charged . . . . . . . . . . . . . . . . . . . . . . 19

3 General information on refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.1 Components of refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.2 Layout of components of refrigerant circuit and their influence on high-pressure and low-

pressure sides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.3 Design of refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.4 Refrigerant circuit with electrically driven air conditioner compressor . . . . . . . . . . . . . . . . 40

3.5 Connections for quick-release coupling in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . 41

3.6 Switches and senders in refrigerant circuit and related connections . . . . . . . . . . . . . . . . 47

3.7 Electrical components not installed in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . 55

3.8 Pressures and temperatures in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

3.9 Tests and measurements performed with pressure gauge . . . . . . . . . . . . . . . . . . . . . . . . 60

3.10 Air conditioner service and recycling units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.11 Repair notes for refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4 Laws and regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

4.1 Laws and regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

5 Refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.1 Important repair notes for air conditioning systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.2 Converting refrigerant circuits from refrigerant R12 to refrigerant R134a . . . . . . . . . . . . . . 68

5.3 Working with the air conditioner service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

5.4 Blowing out refrigerant circuit with compressed air and nitrogen . . . . . . . . . . . . . . . . . . . . 84

5.5 Cleaning (flushing) refrigerant circuit with refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . 88

5.6 Tracing leaks in refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

6 Problems with refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

6.1 Possible complaints about refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

7 Connecting air conditioner service station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

7.1 Connecting air conditioner service station - vehicles with a connection on the low-pressure

and high-pressure side of the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

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

8 Checking pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

side of the refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

Contents i

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

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

switched off) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

8.2 Checking pressures - vehicles with restrictor and reservoir (with internally regulated air

conditioner compressor) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

8.3 Checking pressures - vehicles with expansion valve and receiver (with internally regulated

air conditioner compressor) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194

8.4 Checking pressures - vehicles with restrictor, reservoir and air conditioner compressor

regulating valve N280 (with externally regulated air conditioner compressor) . . . . . . . . . . 200

8.5 Checking pressures - vehicles with expansion valve, receiver and air conditioner compressor

regulating valve N280 (with externally regulated air conditioner compressor) . . . . . . . . . . 207

8.6 Checking pressures - vehicles with electrically driven air conditioner compressor (vehicles

with high-voltage system) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

9 Renewing components of refrigerant circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

9.1 Renewing components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

10 Capacities for refrigerant R134a/refrigerant oil and approved refrigerant oils . . . . . . . . . . 276

10.1 Capacities for refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

10.2 Approved refrigerant oils and refrigerant oil capacities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

11 Test equipment and tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

11.1 List of testers, tools and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

11.2 Tools and materials available from regional sales centre or importer . . . . . . . . . . . . . . . . 363

11.3 Commercially available tools and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

11.4 Improvised tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367

ii Contents

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

87 – Air conditioning system

1 Safety precautions

(ARL006445; Edition 05.2019)

⇒ “1.1 Safety precautions when working on air conditioners”, page 1

⇒ “1.2 Safety precautions when handling refrigerants”, page 1

⇒ “1.3 Safety precautions when working on vehicles with start/ stop system”, page 2

⇒ “1.4 Safety precautions when working on vehicles with highvoltage system”, page 2

⇒ “1.5 Safety precautions when working in the vicinity of highvoltage components”, page 3

⇒ “1.6 Safety precautions when using testers and measuring in‐ struments during a road test”, page 4

1.1 Safety precautions when working on air conditioners

Risk of explosion due to ignition sources - risk of death!

Danger to life and risk of explosion if ignition sources are close to air conditioners and refrigerant vessels. Escaping refrigerant may ignite and cause an explosion. Danger of severe or fatal injuries due to explosion.

– Always keep ignition sources away from air conditioners or

refrigerant vessels.

– Avoid electrostatic discharge, sparks from the striking of tools

and hot surfaces.

Risk of irreparable damage to refrigerant lines

Risk of irreparable damage to refrigerant lines if the inside film is torn.

– Never bend refrigerant lines which have a radius smaller than

r = 100 mm.

1.2 Safety precautions when handling refrigerants

Danger of asphyxiation and poisoning from refrigerant

Refrigerant vapour can cause dry coughs, nausea and even as‐ phyxiation or poisoning.

– Never inhale refrigerant vapour.

– Always perform work on the refrigerant circuit and keep re‐

frigerant vessels in well ventilated areas.

– Never work in cellars, near cellar entrances or in or near other

underground areas.

– Switch on extraction systems.

1. Safety precautions 1

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Risk of frostbite from refrigerant

Pressurised refrigerant can escape during work on the air condi‐ tioner. Risk of frostbite on skin and other parts of the body

– Put on protective gloves.

– Put on safety goggles.

– Extract/drain refrigerant and then immediately open up refrig‐

erant circuit.

– Extract/drain refrigerant again if more than 10 minutes have

passed since initial extraction and refrigerant circuit has not been opened up. Renewed evaporation has created pressure in the refrigerant circuit.

1.3 Safety precautions when working on vehicles with start/stop system

Risk of injury - engine may start unexpectedly

The engine can start unexpectedly if the vehicle's start/stop sys‐ tem is activated. A message in the instrument cluster indicates whether the start/stop system is activated.

– To deactivate the start/stop system, switch off the ignition.

1.4 Safety precautions when working on vehicles with high-voltage system

High voltage can cause fatal injury.

The voltage levels in the high-voltage system constitute a safety hazard. Danger of severe or fatal injuries from electric shock or electric arcs.

– The high-voltage system must be de-energised before any

work is performed on the high-voltage system.

– For work that does not affect the high-voltage system directly,

the high-voltage system must also be de-energised in some cases.

– Please note the work for which the high-voltage system must

be de-energised ⇒ Rep. gr. 00 ; Assessing high-voltage sys‐ tem risk level .

– Have an Audi high-voltage technician (HVT) or an Audi high-

voltage expert (HVE) de-energise the high-voltage system.

Risk of injury - engine may start unexpectedly

It is difficult to determine whether the drive system of an electric vehicle or hybrid vehicle is active. Moving parts can trap or draw in parts of the body.

2 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

– Switch off ignition.

– Place ignition key outside vehicle.

Risk of injury if auxiliary air conditioner is activated

On electric and hybrid vehicles, the auxiliary air conditioner can switch itself on if it has been activated. The radiator fans can start up automatically and trap or draw in parts of the body.

– Deactivate auxiliary air conditioner.

1.5 Safety precautions when working in the vicinity of high-voltage components

High voltage can cause fatal injury.

The voltage levels in the high-voltage system constitute a safety hazard. Danger of severe or fatal injuries from electric shock or electric arcs if high-voltage components or high-voltage wiring are damaged.

– Carry out a visual check of high-voltage components and high-

voltage wiring.

– Never use cutting/forming tools or other sharp-edged imple‐

ments in the vicinity of high-voltage components and highvoltage wires.

– Never perform work using welding, brazing, thermal bonding

or hot air in the vicinity of high-voltage components or highvoltage wires.

Risk of damage to high-voltage wiring

Incorrect handling may result in damage to the insulation of highvoltage wires or high-voltage connectors.

– Never use high-voltage wiring or high-voltage connectors as

a support.

– Never prop tools against high-voltage wiring or high-voltage

connectors.

– High-voltage cables must not be excessively bent or kinked.

– Pay attention to coding when connecting high-voltage con‐

nections.

1. Safety precautions 3

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

1.6 Safety precautions when using testers and measuring instruments during a road test

Risk of injury if test equipment is not secured

If an accident occurs and the front passenger's airbag is triggered, test equipment which is not secured adequately may be catapul‐ ted through the vehicle with potentially serious consequences.

– Secure test equipment on the rear seat with a strap.

Or:

– Have a second mechanic operate test equipment on the rear

seat.

4 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

2 General information on air condition‐

ing systems

⇒ “2.1 Introduction”, page 5

⇒ “2.2 Other reference material ”, page 5

⇒ “2.3 Principles of air conditioning systems”, page 6

⇒ “2.4 Refrigerant R134a”, page 8

⇒ “2.5 Properties of refrigerant R134a”, page 10

⇒ “2.6 Refrigerant oil”, page 12

⇒ “2.7 How air conditioning works”, page 13

⇒ “2.8 General work safety”, page 14

⇒ “2.9 Product properties”, page 15

⇒ “2.10 Handling refrigerant”, page 15

⇒ “2.11 Handling pressure vessels”, page 16

⇒ “2.12 Basic rules for working on refrigerant circuit”, page 17

⇒ “2.13 Before using air conditioner after system has been recharged”, page 19

2.1 Introduction

This manual is intended to provide foremen and mechanics with the basic knowledge needed to ensure reliable and successful repairs.

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 available for presentation to the responsible supervisory agency on request.

2.2 Other reference material

♦ Workshop Manual for model-specific maintenance work ⇒

Heating, air conditioning; Rep. gr. 87 ; Overview of fitting lo‐ cations - air conditioner (vehicle-specific Workshop Manual) and ⇒ Current flow diagrams, Electrical fault finding and Fitting locations

♦ Technical Service Handbook (TPI) 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 training courses for dealerships

♦ List of special tools and workshop equipment required for re‐

pairing the air conditioner ⇒ Electronic parts catalogue (Tools; Workshop equipment/tools; Air conditioner/heater).

♦ Service Organisation Handbook, Vol. 1 “Additional equipment”

⇒ Audi ServiceNet, Handbooks

2. General information on air conditioning systems 5

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

♦ Workshop Manual: Air conditioner with refrigerant R12 (for

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

2.3 Principles of air conditioning systems

⇒ “2.3.1 Physical principles”, page 6

⇒ “2.3.2 Pressure and boiling point”, page 6

⇒ “2.3.3 Vapour pressure table for refrigerant R134a”, page 7

⇒ “2.5 Properties of refrigerant R134a”, page 10

2.3.1 Physical principles

The four familiar states of water apply to air conditioning refriger‐ ants, too.

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.

2.3.2 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 liquid changes, its boiling point also changes.

6 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Note

Pressure can be measured in various units: 1 MPa (megapascal) is equivalent to 10 bar gauge pressure, or 145 psi; 1 bar absolute pressure is the same as 0 bar gauge pressure, which is roughly equivalent to atmospheric pressure.

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

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

Vapour pressure curve for water

A - Liquid

B - Gaseous

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 - Gaseous

D - Vapour pressure curve for refrigerant R134a

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

2.3.3 Vapour pressure table for refrigerant R134a

The vapour pressure table for every refrigerant is published in the 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 characteristic vapour pressure table for every refrig‐ erant, it is possible to identify the type of refrigerant by measuring pressure and temperature.

2. General information on air conditioning systems 7

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

“0 bar absolute pressure” corresponds to an absolute vacuum. The normal ambient pressure (atmospheric pressure) corre‐ sponds to approx. “1 bar absolute pressure”. On the scales of most pressure gauges, “0 bar” corresponds to an absolute pressure of 1 bar (this is also indicated by the value “-1” ap‐ pearing below “0”).

♦

Pressure can be measured in various units: 1 MPa (mega‐ pascal) is equivalent to 10 bar gauge pressure, or 145 psi; 1 bar absolute pressure is the same as 0 bar gauge pressure, which is roughly equivalent to atmospheric pressure.

Temperature in °C Pressure in bar (gauge pres‐

sure), 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

2.4 Refrigerant R134a

Air conditioning systems in vehicles use a vaporisation and con‐ densation process. These systems employ a substance with a low boiling point, referred to as refrigerant.

The refrigerant used is tetrafluoroethane or R134a, which boils at

-26.5°C at a vapour pressure of “1 bar absolute pressure” (cor‐ responds approx. to ambient pressure).

8 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

⇒ “2.4.1 Physical properties of refrigerant R134a”, page 9

⇒ “2.4.2 Critical point”, page 9

⇒ “2.4.3 Environmental aspects of refrigerant R134a”, page 9

2.4.1 Physical properties 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)

2.4.2 Critical point

The critical point (critical temperature and critical pressure) is the point 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 7 “Vapour pressure table”.

Note

Different types of refrigerant must never be mixed. The refrigerant specified for the respective air conditioning system must be used exclusively.

2.4.3 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-depleting

potential is zero.

♦ The global warming potential (GWP) of R134a is approx. 1400

(GWP of carbon dioxide = 1). To reduce the impact of refrig‐ erant R134a on global warming, the European Commission has ruled that vehicles with air conditioners using refrigerant with a GWP higher than 150 may no longer be made available on the market from 1 January 2017 onwards. Air conditioners in vehicles which were made available on the market before 31 December 2016 may be filled and operated with refrigerant R134a until further notice.

♦ The global warming effect of R134a is ten times less than that

of refrigerant R12.

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2.5 Properties of refrigerant R134a

⇒ “2.5.1 Trade names and designations”, page 10

⇒ “2.5.2 Colour”, page 10

⇒ “2.5.3 Vapour pressure”, page 10

⇒ “2.5.4 Physical properties of R134a”, page 10

⇒ “2.5.5 Reaction with metals”, page 11

⇒ “2.5.6 Critical temperature/critical pressure”, page 11

⇒ “2.5.7 Water content”, page 11

⇒ “2.5.8 Combustibility”, page 11

⇒ “2.5.9 Charge factor”, page 11

⇒ “2.5.10 Tracing leaks”, page 11

2.5.1 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 designations Frigen and Freon are trade names. They also apply to refrigerants which should not be used in vehicles.

2.5.2 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 tube of charging cylinder or bubbles in a 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.

2.5.3 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 when the system is pressurised and is often called vapour pressure. Vapour pressure is dependent on temperature

⇒ page 7 “Vapour pressure table”.

2.5.4 Physical properties of R134a

As the vapour pressure curves of R134a and other refrigerants are sometimes very similar, a clear identification is not possible based merely on the pressure.

When using R134a, the air conditioner compressor is lubricated with special synthetic refrigerant oils, e.g. PAG oils (polyalkylene glycol oils).

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2.5.5 Reaction with metals

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

However, refrigerant impurities such as chlorine compounds cause corrosion of certain metals and plastics. This can cause blockages, leaks and deposits on the air conditioner compressor piston.

2.5.6 Critical temperature/critical pressure

The refrigerant R134a remains chemically stable up to a gas pressure of 39.5 bar (40.56 bar absolute pressure; corresponds to a temperature of 101 °C). Above this temperature, the refrig‐ erant decomposes (see "Combustibility").

2.5.7 Water content

Only very small amounts of water are soluble in liquid refrigerant. In contrast, 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 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 will then no longer provide any cooling effect.

Water causes irreparable damage to the air conditioner because at high pressures and temperatures it combines with other im‐ purities to form acids.

2.5.8 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 (produced for example during electric welding) also causes refrigerant decomposition. The re‐ sultant decomposition products are toxic and must not be inhaled. However, these chemicals irritate the mucous membranes, giving adequate warning of their presence.

2.5.9 Charge factor

A container 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 forces are sufficient to rupture the vessel. To stop containers being overfilled, regulations governing the storage of compressed gases specify the number of kilograms of refrigerant with which a container may be filled per litre of internal volume. The maximum permissible capacity is calculated by multiplying this "charge factor" by the internal volume of the vessel. The charge factor for refrigerant used in motor vehicles is 1.15 kg/litre.

2.5.10 Tracing leaks

External damage, for example, can cause a leak in the refrigerant circuit. Minor leaks where only a small amount of refrigerant is escaping can be detected using, for example, an electronic leak detector or by adding a UV leak detection additive to the refrig‐ erant circuit. Electronic leak detectors are capable of registering leaks with refrigerant losses of less than 5 g per year.

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Note

It is important to use leak detectors that are designed for the composition of the respective refrigerant type. For example, a leak detector for R12 refrigerant is not suitable for R134a refrig‐ erant because R134a has no chlorine atoms and the leak detector therefore does not respond.

2.6 Refrigerant oil

Caution

♦ For information on how to handle refrigerant oil, refer to ⇒

Audi ServiceNet, HSO Environmental Protection (or ⇒ Volkswagen ServiceNet, Handbooks, Service Handbook; Environmental Protection ) and observe local regulations.

Refrigerant oil mixes with the refrigerant (in a ratio of about 20 - 40 %, depending on compressor type and quantity of refrig‐ erant) 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, so it is important to use only the approved types of oil.

⇒ Electronic parts catalogue.

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

Note

♦

Do not store refrigerant oil in open containers as it is extremely hygroscopic (it attracts water).

♦

Always keep oil containers sealed.

♦

Do not re-use old refrigerant oil. Refrigerant oil must be dis‐ posed of as used oil of unknown origin (observe local regula‐ tions) ⇒ Audi ServiceNet, HSO Environmental Protection (or ⇒ Volkswagen ServiceNet, Handbooks, Service Handbook; Environmental Protection ).

♦

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

⇒ “2.6.1 Properties of refrigerant oil”, page 12

2.6.1 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 oils. For a list of approved refrigerant oils and capacities, refer to

⇒ page 317 .

PAG oils for refrigerant R134a are highly hygroscopic and do not mix with other oils. Opened containers should therefore be closed again immediately to prevent moisture from entering. Moisture

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and acids cause refrigerant oil to age, making it dark, viscous and corrosive to metals.

Note

♦

Due to its chemical properties, refrigerant oil must not be dis‐ posed of together with engine oil or gear oil. Refrigerant oil must be disposed of as used oil of unknown origin (observe local regulations) ⇒ Audi ServiceNet, HSO Environmental Protection (or ⇒ Volkswagen ServiceNet, Handbooks, Service Handbook; Environmental Protection ).

♦

Only oil approved for the air conditioner compressor may be used for refrigerant circuits containing refrigerant R134a ⇒ Electronic parts catalogue and capacities ⇒ page 317 .

Important information:

As refrigerant oil is extremely hygroscopic, open containers must be closed and re-sealed immediately after use to prevent mois‐ ture from entering.

Note

♦

A use-by date for the refrigerant oil is stated on the bottle in which the refrigerant oil is supplied.

♦

This date is not relevant if the bottle is sealed air-tight.

♦

If the bottle is sealed air-tight, the refrigerant oil can also be used after the date stated on the bottle.

2.7 How air conditioning works

The temperature in the passenger compartment depends on the amount of heat radiated into the vehicle 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 tem‐ perature for the occupants.

As heat is always transmitted away from warmer areas and into cooler areas, the passenger compartment is fitted with a unit for generating low temperatures in which refrigerant 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 by the air con‐ ditioner compressor. Thanks to the action of the compressor, the heat content and temperature of the refrigerant increases. Its temperature is then substantially higher than that of the surround‐ ing 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 will be needed again, 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 as regards the units used.

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⇒ “2.7.1 Comfort of vehicle occupants”, page 14

⇒ “2.7.2 Environmental aspects”, page 14

2.7.1 Comfort of vehicle occupants

A basic requirement for safety and concentration while driving is a feeling of comfort in the passenger compartment. Especially when conditions are hot and humid, a good level of comfort can only be achieved with air conditioning. Passenger comfort can of course also be improved by opening the windows or sun roof, or by increasing the air flow. This, however, involves several draw‐ backs for the occupants, e.g. more noise, draughts, exhaust fumes and unfiltered pollen (unpleasant for allergy sufferers).

Climate control together with a good heating and ventilation sys‐ tem can create a sense of well-being and comfort by regulating temperature, humidity and air circulation in the passenger com‐ partment to suit ambient conditions, both when the vehicle is stationary and when it is moving.

Other important advantages of air conditioning:

♦ Filtration of the air supplied to the passenger compartment

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

♦ Pleasant temperature levels (example: mid-size car after short

travelling time, ambient temperature 30 °C in the shade and vehicle exposed to sunlight)

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

With air conditioning Without air condi‐

tioning

2.7.2 Environmental aspects

Since about 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.

Up until roughly 1992, refrigerant R12 was used for air condition‐ ing systems. Due to its chlorine atoms, this CFC had a high ozone depletion potential as well as potential for intensifying the green‐ house 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).

The global warming potential (GWP) of R134a is approx. 1400; the European Commission has therefore ruled that vehicles using this refrigerant may no longer be made available on the market from 1 January 2017 onwards ⇒ page 9 . From 2016 onwards, refrigerant with a GWP of less than 150 will be used for newly manufactured vehicles (e.g. refrigerant R1234yf with a GWP of less than 5).

For environmental reasons, refrigerants must not be released into the atmosphere ⇒ page 63 (see the relevant environmental leg‐ islation).

2.8 General work safety

♦ In accordance with regulations of the German industrial liabil‐

ity insurance association, VBG 20, (other regulations may apply in other countries)

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♦ Observe specific instructions relating to workplaces where re‐

frigerants are handled ⇒ Audi-ServiceNet, HSO Environmen‐ tal Protection . These instructions must be posted at the workplace.

2.9 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 liquefied under pressure. They are subject to the regulations governing pressure vessels and may only be used in approved and appropriately marked containers.

Specific requirements must be observed to ensure safe and prop‐ er handling:

2.10 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.

The pressure level is governed by two factors:

• The type of refrigerant in the vessel. “Rule: The lower the boil‐

ing point, the higher the pressure.”

• The temperature level. “Rule: The higher the temperature, the

higher the pressure.”

WARNING

♦ Risk of injury (frostbite).

♦ The refrigerant may escape as liquid or vapour.

♦ 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 apron.

Grease and oils dissolve readily in refrigerants. They would there‐ fore damage 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 refrigerant vapour escapes in concentrated form, 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.

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Welding and soldering on refrigeration systems

Before performing welding, brazing or soldering work on vehicles in the vicinity of air conditioning system components, extract re‐ frigerant and remove any remaining refrigerant by blowing out with nitrogen.

The products of refrigerant decomposition due to the effect of heat are not only toxic, but may also have a highly corrosive effect on pipes and system components. The principal substance is hydro‐ gen fluoride.

Pungent odour

A pungent odour indicates that the products of decomposition mentioned above have already formed. Do NOT inhale these substances, otherwise the respiratory tract, lungs and other or‐ gans could be damaged.

First aid

• Following accidental contact with eyes or mucous mem‐ branes, immediately rinse with copious amounts of running water and consult an eye specialist.

• Following accidental contact with the skin, immediately re‐ move clothing affected and rinse skin with copious amounts of water.

• Following accidental inhalation of concentrated refrigerant va‐ pours, the person concerned must 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 head and administer artificial respiration.

⇒ “2.11 Handling pressure vessels”, page 16

2.11 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.

Pressure vessels must never 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 valves, cylinders may only be transported with the protective cap screwed on.

Valves may break off if cylinders are not properly transported.

Never store in the vicinity of radiators.

High temperatures may occur in such areas. High temperatures are also accompanied by high pressures and the maximum per‐ missible vessel pressure may be exceeded.

Do not heat to temperatures above 50 °C

To avoid possible risk, pressure vessel regulations specify that vessels must not be heated to temperatures exceeding 50 °C.

Do not heat in an uncontrolled manner

Do NOT heat with a naked flame. Local overheating can cause structural changes in the material of the vessel, which then reduce its ability to withstand pressure. There is also a danger of refrig‐ erant decomposition due to localised overheating.

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Sealing empty vessels

Empty refrigerant vessels must always be sealed to prevent mois‐ ture from entering. Moisture can cause steel vessels to rust. This weakens the vessel walls. In addition, any rust particles which enter refrigeration systems from storage vessels will cause mal‐ functioning.

2.12 Basic rules for working on refrigerant cir‐ cuit

⇒ “2.12.1 General notes”, page 17

⇒ “2.12.2 Cleaning refrigerant circuit”, page 17

⇒ “2.12.3 Additionally for vehicles with air conditioner compressor without magnetic clutch (with air conditioner compressor regulat‐ ing valve N280 only)”, page 18

⇒ “2.12.4 Additional information on vehicles with high-voltage system”, page 18

⇒ “2.12.5 O-rings”, page 19

2.12.1 General notes

• Observe specific instructions relating to workplaces ⇒ Audi

ServiceNet, HSO Environmental Protection .

• Ensure absolute cleanliness when working.

• Wear safety goggles and gloves when working with refrigerant

and nitrogen.

• Switch on the available workshop exhaust extraction systems.

• Always use air conditioner service station to discharge refrig‐

erant circuit, then unfasten screw connections and renew defective components.

• Use caps to seal off opened components and hoses to prevent

moisture and dirt from entering the system.

• Use only tools and materials intended for refrigerant R134a.

• Seal opened refrigerant oil containers to guard against mois‐

ture.

Note

♦

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

♦

Before starting up air conditioning system, check specified ca‐ pacity for vehicle ⇒ page 276 .

♦

Do not top up refrigerant in circuit; discharge existing refriger‐ ant and re-charge system.

2.12.2 Cleaning refrigerant circuit

The refrigerant circuit must be cleaned (flushed) with refrigerant R134a ⇒ page 88 (or blown out with compressed air and nitro‐ gen ⇒ page 84 ) in the following cases:

– If moisture or dirt has entered the refrigerant circuit (e.g. fol‐

lowing an accident)

– If the refrigerant oil is dark and viscous

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

renewing compressor

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– If the air conditioner compressor has to be renewed due to

“internal” damage (e.g. noise or no output)

Note

When blowing out components with compressed air and nitrogen, always extract the gas mixture escaping from the components with suitable extraction units (workshop extraction system).

2.12.3 Additionally for vehicles with air condi‐ tioner compressor without magnetic clutch (with air conditioner compressor regulating valve - N280- only)

• Only start the engine after the refrigerant circuit has been as‐

sembled completely (constant air conditioner compressor op‐ eration).

• If the engine has to be operated with the refrigerant circuit

empty, only do so for as long as absolutely essential and avoid increased engine speeds.

2.12.4 Additional information on vehicles with high-voltage system

Vehicles with high-voltage system (hybrid vehicles)

♦ For further information on the high-voltage system, refer to ⇒

Rep. gr. 00 ; Safety precautions or ⇒ Electrical system; Rep. gr. 93 ; General warning instructions for work on the highvoltage system .

♦ If work on high-voltage system components is necessary, de-

energise high-voltage system ⇒ Rep. gr. 00 ; Safety precau‐ tions or ⇒ Electrical system; Rep. gr. 93 ; General warning instructions for work on the high-voltage system .

• The engine should only be started after the refrigerant circuit

has been assembled completely.

• On vehicles with battery cooling, hybrid operation is only pos‐

sible with the air conditioner charged and with no air condi‐ tioner faults stored ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode for air conditioner and battery regulation

• After installing the electrically driven air conditioner compres‐

sor and then charging the refrigerant circuit, first start up the compressor via the “Compressor run-in” function of the basic setting routine. Otherwise, the air conditioner compressor may be damaged if refrigerant oil has accumulated in the compres‐ sion chamber of the air conditioner compressor due to inap‐ propriate storage prior to installation. ⇒ Vehicle diagnostic tester, “Guided Fault Finding” function for air conditioner and battery regulation

• An electrically driven air conditioner compressor may only be

activated when the refrigerant circuit is charged. Running the air conditioner compressor with the refrigerant circuit empty could lead to compressor damage ⇒ Vehicle diagnostic tester (“Guided Fault Finding” mode for air conditioner and battery regulation) .

• Before the refrigerant circuit can be discharged, evacuated

and charged, specific electrically operated valves (may vary depending on the refrigerant circuit layout) must be opened (e.g. on the Audi Q7 e-tron) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit and ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

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• To check whether the air conditioner is functioning properly, specific electrically operated valves must be opened or closed (e.g. on the Audi Q7 e-tron) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit and ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

• Depending on the vehicle, high pressure may not be available at the service connection on the high-pressure side in all air conditioner operating modes (e.g. on the Audi Q7 e-tron). The senders installed in the refrigerant circuit must therefore be used to check that the air conditioner in these vehicles is func‐ tioning properly ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit and ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

– To minimise the number of automatic engine starts when the

vehicle's drive system is active during test and measurement work, charge the vehicle batteries e.g. with the battery charger 60A - VAS 5904- in battery standby mode ⇒ Electrical system; General information; Rep. gr. 27 ; Charging battery and ⇒ Electrical system; Rep. gr. 93 ; General warning in‐ structions for work on the high-voltage system .

– For test and measurement work that requires the vehicle's

drive system to be active (READY) or the ignition to be switch‐ ed on, move the selector lever to position “P”, activate the parking brake and take care to keep well clear of the engine when it is running. Set up any tools needed so that they cannot come into contact with moving parts.

2.12.5 O-rings

♦ Use only seals which are resistant to refrigerant R134a and

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

♦ Note the correct inside diameter of the seals used ⇒ Electronic

parts catalogue , ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ Seals may only be used once.

♦ Before fitting, lightly lubricate seals with refrigerant oil (PAG

oil).

2.13 Before using air conditioner after system

has been re-charged

Mechanically driven air conditioner compressor

After air conditioner compressor is attached to engine (before belt is fitted or drive shaft is installed)

⇒ “5.3.6 Starting up air conditioner after charging”, page 81 and

⇒ Heating, air conditioning; Rep. gr. 87 ; Air conditioner com‐ pressor .

– Rotate air conditioner compressor about 10 revolutions by

hand using the magnetic clutch pulley or belt pulley.

After re-charging

⇒ “5.3.6 Starting up air conditioner after charging”, page 81

– Start engine with air conditioner switched off ( air conditioning

system magnetic clutch - N25- and air conditioner compressor regulating valve - N280- are not activated).

– When engine idling speed has stabilised, switch on air condi‐

tioner compressor and run it for at least 10 minutes at idling speed with maximum cooling output.

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Electrically driven air conditioner compressor

– After charging the refrigerant circuit, start the electrically driv‐

en air conditioner compressor first using the “Compressor runin” function of the basic setting

⇒ “5.3.6 Starting up air conditioner after charging”, page 81 and ⇒ Vehicle diagnostic tester, “Guided Fault

Finding” function for air conditioner and battery regulation

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3 General information on refrigerant

circuit

⇒ “3.1 Components of refrigerant circuit”, page 21

⇒ “3.2 Layout of components of refrigerant circuit and their influ‐ ence on high-pressure and low-pressure sides”, page 21

⇒ “3.3 Design of refrigerant circuit”, page 39

⇒ “3.4 Refrigerant circuit with electrically driven air conditioner compressor”, page 40

⇒ “3.5 Connections for quick-release coupling in refrigerant cir‐ cuit”, page 41

⇒ “3.6 Switches and senders in refrigerant circuit and related connections ”, page 47

⇒ “3.7 Electrical components not installed in refrigerant circuit”, page 55

⇒ “3.8 Pressures and temperatures in refrigerant circuit”, page 55

⇒ “3.9 Tests and measurements performed with pressure gauge”, page 60

⇒ “3.10 Air conditioner service and recycling units”, page 61

⇒ “3.11 Repair notes for refrigerant circuit”, page 62

3.1 Components of refrigerant circuit

Caution

Tools or materials (e.g. sealing additives) that have not been approved can damage or impair the system.

Use only tools and materials that have been approved by the manufacturer.

Warranty claims are not accepted if tools or materials that have not been approved are used.

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

• Renew damaged or leaking components of refrigerant circuit

⇒ page 258 .

Note

The following replacement parts were previously filled with nitro‐ gen gas: air conditioner compressor, reservoir, evaporator and condenser. This charge is being gradually discontinued. There‐ fore, little or no pressure equalisation can be perceived when the sealing plugs of the replacement part are unscrewed.

3.2 Layout of components of refrigerant cir‐

cuit and their influence on high-pressure and low-pressure sides

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

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High pressure results from the restrictor or expansion valve form‐ ing a constriction and causing the refrigerant to build up, 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 side: Evaporator, evaporator temperature sensor and air conditioner compressor to separate the sections with high and low gas pressure.

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.

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⇒ “3.2.1 Mechanically driven air conditioner compressor”, page 23

⇒ “3.2.2 Electrically driven air conditioner compressor for vehicles with a high-voltage system”, page 25

⇒ “3.2.3 Condenser”, page 27

⇒ “3.2.4 Evaporator”, page 27

⇒ “3.2.5 Heat exchanger for heat pump operation”, page 28

⇒ “3.2.6 Fluid collector”, page 28

⇒ “3.2.7 Reservoir”, page 29

⇒ “3.2.8 Restrictor”, page 29

⇒ “3.2.9 Receiver”, page 31

⇒ “3.2.10 Expansion valve”, page 32

⇒ “3.2.11 Expansion valve with shut-off valve”, page 32

⇒ “3.2.12 Refrigerant shut-off valves”, page 33

⇒ “3.2.13 Refrigerant line with internal heat exchanger”, page 35

⇒ “3.2.14 Quick-release couplings on refrigerant line”, page 35

⇒ “3.2.15 O-rings”, page 37

⇒ “3.2.16 Pipes and hoses of refrigerant circuit”, page 37

⇒ “3.2.17 High-pressure safety valve”, page 37

⇒ “3.2.18 Non-return valves”, page 38

3.2.1 Mechanically driven air conditioner com‐

pressor

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 is switched on.

♦ An overload protection 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 protection 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.

3. General information on refrigerant circuit 23

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

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

♦

The type plate indicates the refrigerant for which the air con‐ ditioner compressor is designed. A valve regulates the pres‐ sure on the low-pressure side 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 switch‐ ed to internal lubrication by way of a valve.

♦

Depending on the version of the air conditioner compressor, there may be a valve on the high-pressure side of the com‐ pressor which prevents liquid refrigerant from flowing back into the compressor after the air conditioner has been switched off. If an air conditioner compressor with such a valve is installed in a vehicle with a refrigerant circuit with an expansion valve, it may take a relatively long time before the pressure in the high-pressure side drops (the expansion valve is cold and the pressure in the low-pressure side increases rapidly after the compressor is switched off; the expansion valve is closed and the refrigerant can only flow slowly to the low-pressure side). If the air conditioner compressor is switched on, the pressure in the low-pressure side drops, the expansion valve is opened and the refrigerant can flow to the low-pressure side.

♦

On air conditioner compressors with an electromagnetic clutch

-A- and a regulating valve -C-, the electromagnetic clutch -Ais usually only activated in conjunction with regulating valve

-C- ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant cir‐ cuit .

24 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.2.2 Electrically driven air conditioner com‐

pressor for vehicles with a high-voltage system

WARNING

Danger of short circuit

The air conditioner compressor operates at up to 288 V in a speed range between 800 and 8600 rpm.

Avoid contact with the air conditioner compressor when switch‐ ing on the ignition or starting the drive units - danger of short circuit.

♦ The air conditioner compressor draws in refrigerant gas from

the evaporator, compresses it and conveys it to the condens‐ er.

♦ The electric motor of the air conditioner compressor is sup‐

plied with power by the power and control electronics for electric drive - JX1- .

♦ The control unit for air conditioning compressor - J842- inte‐

grated in the air conditioner compressor regulates the speed and thereby the output of the air conditioner compressor ( elec‐ trical air conditioner compressor - V470- ) based on the re‐ quest received via the data bus ⇒ Vehicle diagnostic tester, “Guided Fault Finding” function for air conditioner and battery regulation .

♦ The electrically driven air conditioner compressor is not fitted

with an air conditioner compressor regulating valve - N280- .

♦ Prior to installation, check the air conditioner compressor and

bracket attachment points. The contact surfaces must be clean and free of rust and grease. If this is not the case, treat the contact surfaces accordingly with the contact surface cleaning set - VAS 6410- ⇒ Electrical system; General infor‐ mation; Rep. gr. 97 ; Repairing wiring harnesses and con‐ nectors .

3. General information on refrigerant circuit 25

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

If the control unit for air conditioning compressor - J842- is defective, the amount of refrigerant oil in the new air condi‐ tioner compressor must be adjusted. The refrigerant circuit does not have to be flushed with R134a.

♦

The control unit for air conditioning compressor - J842- and the electrical air conditioner compressor - V470- form one component and cannot be separated at present.

♦

The electrically driven air conditioner compressor is not fitted with -N280- . The output of the air conditioner compressor is regulated externally by way of the air conditioner compressor speed ⇒ Current flow diagrams, Electrical fault finding and Fit‐ ting locations and ⇒ Vehicle diagnostic tester, “Guided Fault Finding” function for air conditioner and battery regulation .

♦

At present, the electrically driven air conditioner compressor operates on the principle of a scroll-type supercharger (similar to the "G-Lader" supercharger).

♦

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

♦

The type plate indicates the refrigerant for which the air con‐ ditioner compressor is designed.

♦

The integrated electronics regulate the output of the air con‐ ditioner compressor (and thus the pressure on the low-pres‐ sure side) within the specified range (control characteristic) by way of the speed.

♦

The engine should only be started after the refrigerant circuit has been assembled completely.

♦

The air conditioner compressor is fitted with a secured oil sup‐ ply to prevent damage if the refrigerant circuit is empty. This

means that approx. 40 to 50 cm3 of refrigerant oil remains in the air conditioner compressor.

♦

Like the mechanically driven air conditioner compressor, the electrically driven air conditioner compressor has a pressure relief valve.

♦

On vehicles with battery cooling, hybrid operation is only pos‐ sible with the air conditioner charged and with no air condi‐ tioner faults stored ⇒ Vehicle diagnostic tester, “Guided Fault Finding” function for air conditioner and battery regulation .

♦

After installing the electrically driven air conditioner compres‐ sor and then charging the refrigerant circuit, first start up the compressor via the “Compressor run-in” function of the basic setting routine. Otherwise, the air conditioner compressor may be damaged if refrigerant oil has accumulated in the compres‐ sion chamber of the air conditioner compressor due to inap‐ propriate storage prior to installation ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode for air conditioner and battery regulation .

♦

An electrically driven air conditioner compressor may only be activated when the refrigerant circuit is charged. Running the air conditioner compressor with the refrigerant circuit empty could lead to compressor damage ⇒ Vehicle diagnostic tester (“Guided Fault Finding” mode for air conditioner and battery regulation) .

26 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.2.3 Condenser

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

When this happens, the refrigerant gas condenses to liquid.

Note

♦

Depending on the design of the refrigerant circuit, the receiver may be attached to the condenser or integrated in the con‐ denser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

♦

There are different versions of the condenser; from the outside these versions can only be identified by their part number. Version -1- of the condenser is split into two sections (“twopass condenser”). Version -2- of the condenser is split into four sections (“four-pass condenser”).

♦

This illustration shows a condenser with the receiver -C- at‐ tached.

♦

The gaseous refrigerant enters the condenser at connection

-A-; the refrigerant is then cooled down in the condenser and turns into liquid.

♦

The liquid refrigerant accumulates in receiver -C- (with dryer) and flows through the bottom cooling section to connection

-B-.

♦

The refrigerant capacity in a refrigerant circuit may differ de‐ pending on the design of the condenser (internal volume, flow, etc.). Therefore always pay attention to the correct version and allocation of the condenser ⇒ page 276 and ⇒ Electronic parts catalogue .

3.2.4 Evaporator

Evaporators come in different versions. Depending on the layout and function, the thermal energy required to evaporate the refrig‐ erant is taken from the air flowing through the evaporator (e.g. in the case of the evaporator in the air conditioning unit or in the battery cooling module) or the coolant flowing through the evap‐ orator (e.g. in the case of the heat exchanger for high-voltage battery) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

Note

Two evaporator versions are described below.

3. General information on refrigerant circuit 27

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Evaporator in the air conditioning unit (or in the battery cooling module)

The liquid refrigerant evaporates in the tubes of the evaporator. The heat required for this is extracted from the air flowing past the evaporator fins. The air cools down. The refrigerant evaporates and is extracted from the air conditioner compressor with the ab‐ sorbed heat.

A defined quantity of refrigerant is supplied to the evaporator by way of a restrictor or expansion valve. In systems with an expan‐ sion valve, the flow rate is regulated so that only gaseous refrig‐ erant emerges at the evaporator outlet.

Evaporator/heat exchanger for high-voltage battery (chiller)

The liquid refrigerant evaporates in the evaporator (heat ex‐ changer). The heat required for this is extracted from the coolant flowing through the evaporator. The coolant cools off, and the re‐ frigerant evaporates and is drawn in by the air conditioner com‐ pressor with the absorbed heat.

A specified quantity of refrigerant is supplied to the evaporator via a restrictor (or an expansion valve) and a shut-off valve. The flow rate of the refrigerant (or coolant) is regulated so that the refrig‐ erant emerging from the evaporator outlet is in gaseous form only ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐ hicle-specific Workshop Manual).

3.2.5 Heat exchanger for heat pump opera‐ tion

The refrigerant (gaseous or vaporous) compressed by the air conditioner compressor is liquefied in the heat exchanger -A-; the released heat is transferred to the coolant flowing through ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehiclespecific Workshop Manual).

3.2.6 Fluid collector

In certain operating modes (e.g. in heat pump mode), the receiver (e.g. on the condenser). is not incorporated in the refrigerant cir‐ cuit. The fluid collector -B- collects the refrigerant, stores a certain amount of it (if not required) and then transfers it as a continuous flow to the expansion valve (in front of the evaporator in the heater and air conditioning unit) or to the heat exchanger in the highvoltage system's coolant circuit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

28 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.2.7 Reservoir

The reservoir collects the vapour and gas mixture coming from the evaporator to ensure that the air conditioner compressor only receives gaseous refrigerant. The vapour turns into gaseous re‐ frigerant.

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

Any moisture which enters the refrigerant circuit during assembly is trapped by a filter (desiccant bag) in the reservoir.

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

Note

♦

Renew reservoir if refrigerant circuit has been open for a rel‐ atively long period and moisture has entered, or if renewal is stipulated due to a specific complaint ⇒ page 258 .

♦

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

♦

If a reservoir is not sealed, the desiccant bag soon becomes saturated with moisture and can no longer be used.

♦

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

3.2.8 Restrictor

Restrictor upstream of evaporator

The restrictor creates a constriction. The restriction restricts the flow, thus separating the refrigerant circuit into high and low-pres‐ sure sides. Upstream of the restrictor, the refrigerant is warm due to the high pressure. Downstream of the restrictor, the refrigerant is cold due to the low pressure. A strainer is fitted upstream of the constriction to trap dirt. The strainer downstream of the constric‐ tion is designed to atomise the refrigerant before it enters the evaporator.

Note

♦

Arrow -A- on restrictor faces evaporator.

♦

Always renew after opening circuit.

♦

There are different versions; observe the notes in the service information media available ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

Restrictor upstream of heat exchanger for high-voltage battery (chiller)

3. General information on refrigerant circuit 29

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

The restrictor creates a restriction, which restricts the flow, thus separating the refrigerant circuit into high and low-pressure sides. Upstream of the restrictor, the refrigerant is warm due to the high pressure. Downstream of the restrictor, the refrigerant is cold due to the low pressure.

Note

♦

The illustration shows a refrigerant line -A- with a permanently installed restrictor -B- (without strainer).

♦

The diameter of the restrictor hole -B- is approx. 0.7 mm. De‐ pending on the version of the refrigerant line, the restrictor is either only inserted or fixed in position in the refrigerant line. If it is inserted, there may be a strainer for separating float ele‐ ments, which may block off the restrictor hole.

♦

Prior to installation, check for dirt, and clean or renew the component as necessary.

♦

30 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.2.9 Receiver

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

Note

♦

Renew receiver if refrigerant circuit has been open for a rela‐ tively long period and moisture has entered, or if renewal is stipulated due to a specific complaint ⇒ page 258 .

♦

Do not remove sealing plugs until just before installation.

♦

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 integrated in the condenser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐ erant circuit (vehicle-specific Workshop Manual) and ⇒ Elec‐ tronic parts catalogue .

♦

The procedure for dealing with problems differs depending on the version of the receiver / desiccant cartridge. If, for example, the receiver is attached to the condenser, it can be renewed together with the desiccant cartridge. If, for example, the re‐ ceiver is integrated into the condenser, it is usually possible to renew the desiccant cartridge and any additional filter element separately. If the receiver is integrated into the condenser and it is not possible to renew the receiver/desiccant cartridge separately, it may be necessary to renew the entire condenser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

♦

Depending on the design of the refrigerant circuit, the desic‐ cant bag (desiccant cartridge) may also be installed in the condenser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐ erant circuit (vehicle-specific Workshop Manual) and ⇒ Elec‐ tronic parts catalogue .

3. General information on refrigerant circuit 31

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

3.2.10 Expansion valve

The expansion valve atomises the refrigerant flowing in and con‐ trols the flow rate according to the heat transfer so that it does not vaporise before reaching the evaporator outlet.

Note

♦

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

♦

Different characteristic curves are matched to the relevant cir‐ cuit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

♦

3.2.11 Expansion valve with shut-off valve

Note

There are different shut-off valve versions with different functions and designations. On the Audi Q5 hybrid, for example, the refrig‐ erant shut-off valve 2 for hybrid battery - N517- (as illustrated below) is installed in the battery cooling module ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

32 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

♦ The expansion valve -A- with -N517- -B- atomises the refrig‐

erant flowing through and regulates the flow of refrigerant to the evaporator in the battery cooling module of the hybrid bat‐ tery unit - AX1- so that - depending on the heat transferred the vapour only turns into gas at the outlet of the evaporator.

♦ When -N517- -B- is actuated by the electronic system, it is

open and allows refrigerant to flow through the expansion valve -A- to the evaporator in the battery cooling module.

♦ The expansion valve -A- with -N517- -B- is installed on vehi‐

cles with battery cooling module. It is actuated in air condi‐ tioning mode if the hybrid battery unit - AX1- needs to be cooled.

♦ If -N517- -B- is actuated by the electronic system (e.g. by the

battery regulation control unit - J840- ), it is opened and allows refrigerant to flow to the evaporator in the battery cooling mod‐ ule according to its control characteristics.

♦ The solenoid -N517- -B- (fitted at expansion valve -A-) is ac‐

tivated e.g. by the battery regulation control unit - J840- ⇒ Cur‐ rent flow diagrams, Electrical fault finding and Fitting locations and ⇒ Vehicle diagnostic tester (“Guided Fault Finding” for air conditioner and battery regulation) .

♦ If, on a vehicle with two evaporators (one each in the air con‐

ditioning unit and battery cooling module as e.g. on the Audi Q5 Hybrid), the measured temperature corresponds to or is below the specified value at one evaporator but the required specified value is not attained at the other evaporator, the sys‐ tem is controlled as follows: the battery regulation control unit

- J840- actuates the electric air conditioner compressor at a higher speed via the power and control electronics for electric drive - JX1- and the control unit for air conditioning compressor

- J842- . This causes the cooling output of the air conditioner to increase and the pressure on the low-pressure side and the evaporator temperature to drop. If the required temperature value is then not reached at one evaporator, -J840- activates the refrigerant shut-off valve 1 for hybrid battery - N516- or the refrigerant shut-off valve 2 for hybrid battery - N517- so that refrigerant no longer flows through the evaporator which is too cold ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode for air conditioner .

3.2.12 Refrigerant shut-off valves

Note

♦

There are different shut-off valve versions with different func‐ tions and designations. For example, the refrigerant shut-off valve 1 for hybrid battery - N516- (as illustrated below) is in‐ stalled in the Audi Q5 hybrid ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐ ual).

♦

Different designations, depending on the function and vehicle ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

Shut-off valve with two switch statuses (open and closed)

♦ Refrigerant shut-off valve 1 for hybrid battery - N516- (e.g. on

the Audi Q5 hybrid)

♦ Refrigerant shut-off valve for heater and air conditioner unit -

N541- (e.g. on the Audi A3 e-tron)

3. General information on refrigerant circuit 33

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

♦ Refrigerant shut-off valve for high-voltage battery heat ex‐

changer - N542- (e.g. on the Audi A3 e-tron)

♦ Refrigerant shut-off valve - V424- (e.g. on the Audi Q7 e-tron)

♦ When the shut-off valve -A- is not actuated by the electronic

system, it is open and allows refrigerant to flow to the evapo‐ rator in the air conditioning unit.

♦ The shut-off valve -A- is e.g. installed on vehicles with battery

cooling module. It is actuated in hybrid mode if the air condi‐ tioner is not set to cooling mode for the passenger compart‐ ment, but the hybrid battery unit - AX1- needs to be cooled.

♦ Observe the arrow -B- on the shut-off valve -A-; it shows the

flow direction of the refrigerant (from condenser to evaporator in the air conditioning unit).

♦ The solenoid -C- (fitted at the shut-off valve) is actuated e.g.

by the battery regulation control unit - J840- ⇒ Current flow diagrams, Electrical fault finding and Fitting locations and ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode for air conditioner and battery regulation .

♦ If e.g. on a vehicle with two evaporators (one each in the air

conditioning unit and battery cooling module as e.g. on the Audi Q5 Hybrid), the measured temperature corresponds to or is below the specified value at one evaporator but the re‐ quired specified value is not attained at the other evaporator, the system is controlled as follows: the relevant control unit (e.g. the control unit for battery regulation - J840- on the Audi Q5 Hybrid) actuates the electric air conditioner compressor at a higher speed via the control unit for air conditioning com‐ pressor - J842- . This causes the cooling output of the air conditioner to increase and the pressure on the low-pressure side and the evaporator temperature to drop. If the required temperature value is then not reached at one evaporator, the responsible control unit (e.g. -J840- on the Q5 hybrid) acti‐ vates the refrigerant shut-off valve 1 for hybrid battery - N516or the refrigerant shut-off valve 2 for hybrid battery - N517- so that refrigerant no longer flows through the evaporator which is too cold ⇒ Vehicle diagnostic tester in “Guided Fault Find‐ ing” mode for air conditioner and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

Shut-off valves controlled via characteristic curves

♦ Refrigerant shut-off valve 2 - N640- to refrigerant shut-off valve

5 - N643- (e.g. on the Audi Q7 e-tron)

♦ Refrigerant expansion valve 1 - N636- (e.g. on the Audi Q7 e-

tron)

34 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

♦ Shut-off valve -A- is activated using a stepper motor -B- of the

corresponding control unit via characteristic curves (open or closed).

♦ If the shut-off valve is operating as a control valve (e.g. as the

refrigerant expansion valve 1 - N636- on the Audi Q7) it is only opened as far as necessary until the specified temperature for the heat exchanger is reached ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ The shut-off valves activated by stepper motors have no speci‐

fied rest position. They must therefore be moved to a specific position (open or closed) before any work is performed on the refrigerant circuit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ Depending on the layout of the refrigerant circuit, several shut-

off valves may be combined in one valve block (e.g. on the Audi Q7 e-tron) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ The stepper motor is adapted and activated via data lines (LIN

bus) by the corresponding control unit according to their fitting location ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Vehicle di‐ agnostic tester (“Guided Fault Finding”).

3.2.13 Refrigerant line with internal heat ex‐ changer

In this refrigerant line, the hot refrigerant (liquid) flowing through the high-pressure side gives off energy to the cold refrigerant (gaseous or vaporous) flowing through the low-pressure side, thus enhancing the efficiency of the air conditioner.

Note

This illustration shows a refrigerant line with internal heat ex‐ changer as fitted e.g. on the Audi A4 2008 > and the Audi A5 Coupé 2008 > ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐ erant circuit (vehicle-specific Workshop Manual).

A - Refrigerant line with internal heat exchanger

B - Passages in refrigerant line, in which hot liquid refrigerant flows to evaporator (high-pressure side of refrigerant circuit)

C - Passage in refrigerant line, in which cold gaseous or vaporous refrigerant flows to air conditioner compressor (low-pressure side of refrigerant circuit)

3.2.14 Quick-release couplings on refrigerant line

WARNING

Only release and open the quick-release couplings after com‐ pletely discharging the refrigerant circuit.

3. General information on refrigerant circuit 35

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

This illustration shows the quick-release couplings with a re‐ frigerant line with internal heat exchanger as fitted e.g. on the Audi A4 2008 > and the Audi A5 Coupé 2008 > ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

Removal of the refrigerant line -D- involves opening the re‐ taining ring -A- with the refrigerant line release tool -T40149/for example ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

Following removal of the applicable refrigerant line, renew the quick-release couplings -B- and -G- together with the corre‐ sponding support ring -E- or -H- and the corresponding O-ring

-F- or -J- ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

A - Retaining ring (in quick-release coupling, high-pressure side)

B - Quick-release coupling with retaining ring (high-pressure side)

C - Refrigerant line with internal heat exchanger

D - Refrigerant line (high-pressure side)

E - Support ring (high-pressure side)

F - O-ring (“high-pressure side”)

G - Quick-release coupling with retaining ring (low-pressure side)

H - Support ring (low-pressure side)

J - O-ring (“low-pressure side”)

Note

♦

There are different versions of the quick-release couplings

-A- and -D-. With both versions of these quick-release cou‐ plings, the refrigerant lines -C- can be released in the identical manner using the refrigerant line release tool -T40149/1- for 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 -D- installed from model year 2010 onwards (gradual introduction), the refrigerant line -C- is installed in the same way as with the quick-release coupling

-A-. If, on this version, the refrigerant line -C- is pulled in the direction of the arrow after it is assembled, the snap ring -Eemerges from the quick-release coupling -D-, showing that the retaining ring -F- is completely locked onto the refrigerant line

-C-. The snap ring -E- is then to be detached from the refrig‐ erant line -C-.

36 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.2.15 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 if genuine replace‐ ment parts are used.

O-rings:

– Use only once.

– Observe correct diameters -a- and -b-.

– Before installing, lubricate lightly with refrigerant oil ⇒ Heating,

air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-spe‐ cific Workshop Manual) and ⇒ Electronic parts catalogue .

Note

The colour coding of O-rings for R134a refrigerant circuits has been discontinued. Black and coloured O-rings are used ⇒ Elec‐ tronics parts catalogue and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

3.2.16 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 replacement parts.

The pipes and hoses are joined with bolted connections or special connectors.

Note

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

3.2.17 High-pressure safety valve

The high-pressure safety valve is attached to the air conditioner compressor or the 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 escapes.

3. General information on refrigerant circuit 37

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

Depending on the version, a transparent plastic disc -B- may be attached to the high-pressure safety valve -A-. The disc breaks off as soon as the valve is actuated.

♦

Depending on the version of the high-pressure safety valve

-A-, there may also be a cover -C- on the high-pressure safety valve -A-. Should the pressure in the refrigerant circuit ever exceed the opening pressure of the high-pressure safety valve

-A-, causing the high-pressure safety valve to open, the re‐ frigerant does not emerge in one direction but is distributed through the openings -D- under the cover -C-.

♦

Should it be necessary to renew a high-pressure safety valve

-A-, please observe the correct tightening torque when instal‐ ling (dependent on air conditioner compressor manufacturer and version). On air conditioner compressors manufactured by Denso (or Nippondenso), Sanden or Zexel/Valeo, an O-ring is fitted (tightening torque: currently 10 Nm for Denso and Zexel/Valeo; 15 Nm for Sanden). On Delphi air conditioner compressors, a seal is fitted (tightening torque: currently 15 Nm).

♦

Renew seal/O-ring ⇒ Electronic parts catalogue .

♦

If the seal/O-ring fitted at the high-pressure safety valve can‐ not be supplied as a replacement part, the removed compo‐ nent can be re-installed as an exception; it must be checked for damage before being re-installed. If the removed seal/Oring is damaged or deformed, it must be replaced by a com‐ mercially available component ⇒ Electronic parts catalogue .

♦

After charging the refrigerant circuit, check the installed highpressure safety valve for leaks, e.g. with an electronic leak detector.

3.2.18 Non-return valves

Non-return valves separate the refrigerant circuit into different sections.

Note

♦

The non-return valve -3- in the illustration is installed e.g. on the Audi Q7 e-tron.

♦

Non-return valves in the refrigerant circuit have a specific holding pressure (approx. 0.1 bar or 100 mbar) in the forward direction. All electrically activated valves must therefore be open so that the refrigerant circuit can be evacuated fully (re‐ sidual pressure less than 5 mbar).

♦

Depending on the version, there may be a sticker indicating the direction of flow.

38 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.3 Design of refrigerant circuit

⇒ “3.3.1 Refrigerant circuit with expansion valve and evaporator”, page 39

⇒ “3.3.2 Refrigerant circuit with restrictor and reservoir”, page 39

⇒ “3.4 Refrigerant circuit with electrically driven air conditioner compressor”, page 40

3.3.1 Refrigerant circuit with expansion valve and evaporator

The following illustration only shows the general layout of a typical refrigerant circuit; refer to the vehicle-specific Workshop Manual for the layout of that vehicle's refrigerant circuit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

1 - Evaporator

2 - Expansion valve

3 - Valve for extraction, charging and measurement

4 - Sight glass (not fitted with R134a circuits)

5 - Receiver with dryer

6 - Condenser

7 - Air conditioner compressor

Note

Arrows show direction of refrigerant flow.

3.3.2 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.

3. General information on refrigerant circuit 39

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

3.4 Refrigerant circuit with electrically driven air conditioner compressor

Note

The following illustration shows the refrigerant circuit fitted in the Audi Q5 hybrid as an example; refer to the vehicle-specific Work‐ shop Manual for the layout of that vehicle's refrigerant circuit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehiclespecific Workshop Manual).

Arrows show direction of refrigerant flow.

1 - Electrically driven air condi‐ tioner compressor

❑ With control unit for air

conditioning compres‐ sor - J842- and electrical air conditioner compres‐ sor - V470-

2 - Condenser

❑ With receiver and desic‐

cant cartridge

3 - Service connection (highpressure side)

4 - Refrigerant shut-off valve 1 for hybrid battery - N516-

❑ Only on vehicles with

battery cooling module for hybrid battery unit AX1-

Note

-N516- is activated, for example, if the battery needs to be cooled but the air conditioner is not set to cool‐ ing mode for the passenger com‐ partment (valve open when not activated).

5 - Expansion valve

❑ At evaporator in air con‐

ditioning unit

6 - Evaporator

❑ Evaporator in air condi‐

tioning unit

7 - Expansion valve with refrig‐ erant shut-off valve 2 for hybrid battery - N517-

❑ At evaporator in battery cooling module ❑ Only on vehicles with battery cooling module for hybrid battery unit - AX1-

Note

-N517- is activated if battery needs to be cooled (closed when not acti‐ vated).

40 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

8 - Evaporator

❑ Evaporator in battery cooling module ❑ Only on vehicles with battery cooling module for hybrid battery unit - AX1-

9 - Service connection (low-pressure side)

3.5 Connections for quick-release coupling in refrigerant circuit

• Only use valves and connections that are resistant to R134a

refrigerant and related refrigerant oils.

• There are different connections (outer diameter) for high and

low-pressure sides.

• Discharge refrigerant circuit before removing valves or valve

cores.

• Always screw on sealing caps.

Layout in vehicle ⇒ Heating, air conditioning; Rep. gr. 87 ; Re‐ frigerant circuit (vehicle-specific Workshop Manual)

WARNING

Risk of injury (frostbite).

Refrigerant may escape if the refrigerant circuit has not been discharged.

Extract refrigerant before opening refrigerant circuit. Renewed evaporation may create pressure in refrigerant circuit if refrig‐ erant circuit is not opened within 10 minutes following extrac‐ tion. Extract refrigerant again.

3. General information on refrigerant circuit 41

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

⇒ “3.5.1 Connections with Schrader valve (needle valve)”, page 42

⇒ “3.5.2 Connections with primary sealing valve (ball valve)”, page 42 ⇒ “3.5.3 Differences in service connections depending on refrig‐ erant (R134a or R1234yf)”, page 45

3.5.1 Connections with Schrader valve (nee‐ dle valve)

♦ -A- Service connection (soldered in)

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

♦ -C- O-ring (for valve)

♦ -D- Sealing cap with seal

Note

♦

After connecting, carefully screw handwheel of service cou‐ pling into quick-release coupling adapter only to the extent required to reliably open valve in service connection (observe pressure gauge; do not open valve too far).

♦

When removing and installing valve core -B- with refrigerant circuit discharged, use e.g. adapter from socket - T10364- .

♦

Take care when tightening valve core -B- (low torque).

♦

There are different versions of these valves; therefore tight‐ ening torques vary. For a valve core -B- with a VG5 thread (5.2 x 0.7 mm, tyre valve) the tightening torque is 0.4 Nm +/- 0.1 Nm; for a valve core with an M6 x 0.75 mm thread, the tightening torque is 0.9 Nm +/- 0.1 Nm, and for a valve core with an M8 x 1.0 mm thread, the tightening torque is

2.0 Nm +/- 0.2 Nm.

♦

There are different versions of these valves, valve cores and corresponding sealing caps. Note the correct version of the valve core and correct assignment of the sealing caps ⇒ Elec‐ tronic parts catalogue .

3.5.2 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.

42 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Connection with high-pressure valve

1 - Connection with internal thread (soldered in)

2 - O-ring (version and identification: black or coloured ⇒ Elec‐

tronic parts catalogue )

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

tion: ball valve)

4 - Seal for cap

5 - Cap

Depending on the vehicle, high pressure may not be available at the service connection on the high-pressure side in all air condi‐ tioner operating modes (e.g. on the Audi Q7 e-tron). The senders installed in the refrigerant circuit must therefore be used to check that the air conditioner in these vehicles is functioning properly ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehiclespecific Workshop Manual) and ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

Note

♦

When removing and installing valve -3- with refrigerant circuit discharged, use e.g. an adapter from socket - T10364- .

♦

There are different versions of these valves (with internal or external thread); therefore the tightening torques may vary. For the valves -3- currently in use (external thread M12 x 1.5 mm) the tightening torque is 9 Nm +/- 1 Nm.

♦

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

3. General information on refrigerant circuit 43

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Connection with low-pressure valve

1 - Connection with external thread and groove for O-ring (sol‐

dered in)

2 - O-ring (version and identification: black or coloured ⇒ Elec‐

tronic parts catalogue )

3 - Valve with internal thread

4 - Seal for cap

5 - Cap

Note

♦

Screw handwheel of service coupling into quick-release cou‐ pling adapter carefully and only to the extent required to reliably open valve in service connection (observe pressure gauge; do not open valve too far).

♦

When removing and installing valve -3- with refrigerant circuit discharged, use e.g. an adapter from socket - T10364- .

♦

There are different versions of these valves (with internal or external thread); therefore the tightening torques may vary. For the valves -3- currently in use (internal thread M10 x 1.25 mm) the tightening torque is 9 Nm +/- 1 Nm.

♦

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

44 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.5.3 Differences in service connections de‐ pending on refrigerant (R134a or R1234yf)

Note

♦

Only use valves and connections which are resistant to the corresponding refrigerant (R134a and/or R1234yf) and related refrigerant oils ⇒ Electronic parts catalogue .

♦

The service connections for the refrigerant circuits are de‐ signed such that only the specified service couplings for the specified refrigerant (R134a or R1234yf) can be connected.

♦

These illustrations show service connections in which a Schrader valve (needle valve or push pin) is installed. How‐ ever, depending on the vehicle version or the type of refriger‐ ant etc., service connections with a primary sealing valve (ball valve) may also be installed (different technology)

⇒ “3.5.2 Connections with primary sealing valve (ball valve)”, page 42 .

♦

Layout in vehicle and on refrigerant circuit ⇒ Heating, air con‐ ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

There are different connections (outer diameter) for high and low-pressure sides.

♦

Discharge refrigerant circuit before removing valves or valve cores

⇒ “5.3.3 Discharging refrigerant circuit with air conditioner service station”, page 73 .

♦

Removing and installing valve from service connection (low and high-pressure sides)

⇒ “3.5.1 Connections with Schrader valve (needle valve)”, page 42 .

♦

Always screw on sealing caps with seal.

3. General information on refrigerant circuit 45

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Service connections (refrigerant R134a and R1234yf)

WARNING

Before removing valves -B, E-, connect the air conditioner service station and extract refrigerant. Refrigerant circuit must be empty; danger of injury

⇒ “5.3.3 Discharging refrigerant circuit with air conditioner service station”, page 73 .

♦ Cap for service connection (high-pressure side) -A- with seal

-G-

♦ Valve core on high-pressure side (version: Schrader valve or

needle valve) -B-

♦ Service connection (high-pressure side) -C-

♦ Cap for service connection (low-pressure side) -D- with seal

-G-

♦ Valve core on low-pressure side (version: Schrader valve or

needle valve) -E-

♦ Service connection (low-pressure side) -F-

Note

♦

Service connections -C, F- for refrigerant R134a and R1234yf are available in different versions (depending on manufactur‐ er), with different sealing caps -A, D- and valves -B, E-. Ensure correct assignment ⇒ Electronic parts catalogue .

♦

Sealing caps -A, D- for the service connections on the R134a refrigerant circuit are currently black. The sealing caps for the service connections on the R1234yf refrigerant circuit are cur‐ rently grey. The refrigerant type (e.g. “R1234yf”) may also be printed on the sealing caps.

♦

After connecting, carefully screw the handwheel of the service coupling into the quick-release coupling adapter only to the extent required to reliably open the valve -B, E- in the service connection (observe the pressure gauge; do not open the valve -B, E- too far).

♦

The service connections -C, F- for R134a and R134yf refrig‐ erant circuits are designed such that only the service couplings specified for the corresponding refrigerant can be connected (different dimensions ⇒ page 47 ).

♦

Service connections -C, F-, for example, are soldered into a refrigerant line and therefore cannot be renewed separately.

♦

To remove and install the valves -B, E- (with the refrigerant circuit drained), make use of an adapter from the socket T10364- for example.

♦

Take care when tightening the valves -B, E- (low torque).

♦

These valves are available in different versions with differing tightening torques. Tightening torque for valve core -C-with a VG5 thread (5.2 x 0.7 mm tyre valve): 0.4 Nm. +- 0.1 Nm; tightening torque for valve core with an M6 x 0.75 mm thread:

0.9 Nm +- 0.1 Nm; tightening torque for valve core with an M8 x 1.0 mm: 2.0 Nm +- 0.2 Nm.

♦

There are different versions of valve caps -A, D-; therefore tightening torques vary. Tightening torque for valve cap with M8 x 1 mm or M10 x 1 mm thread: 0.4 Nm +- 0.1 Nm.

46 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Dimensions of service connections

♦ Valve core -A- (different versions; refer to ⇒ Electronic parts

catalogue )

♦ Service connection -B- (different versions on high-pressure

and low-pressure side depending on refrigerant)

Dimensions of serv‐ ice connections -B-

Outer diameter -D1-

Outer diameter -D2- 14.0 mm 11.0

Offset -L1- 4.6 mm 6.15

Offset -L2- 8.16 mm 9.16

Installation position of valve (not actuated)

-C-

Service connec‐ tion (refrigerant R134a)

Highpressure side

16.0 mm 13.0

6.1 - 7.1mm6.1 - 7.1mm8.3 - 9.3mm8.3 - 9.3

Lowpres‐ sure side

Service connection (refrigerant R1234yf)

Highpressure side

17.0 mm 14.0 mm

13.0 mm 12.0 mm

9.0 mm 4.75 mm

12.5 mm 7.2 mm

Lowpressure side

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

Note

Refer to vehicle-specific refrigerant circuit for switching pres‐ sures, removing and installing switches and location/design of switches ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

3. General information on refrigerant circuit 47

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

⇒ “3.6.1 High-pressure switch for air conditioning system F23 ”, page 48

⇒ “3.6.2 High-pressure switch for magnetic clutch F118 ”, page 48

⇒ “3.6.3 Low-pressure switch for air conditioning system F73 ”, page 49

⇒ “3.6.5 Air conditioning system pressure switch F129 ”, page 49

⇒ “3.6.6 High-pressure sender G65 and pressure sender for re‐ frigerant circuit G805 ”, page 50

⇒ “3.6.7 Refrigerant pressure and temperature sender”, page 51

⇒ “3.6.4 Connections with valve for refrigerant circuit switches”, page 49

⇒ “3.6.8 Air conditioner compressor regulating valve N280 ”, page 54

⇒ “3.6.9 Air conditioner compressor speed sender G111 ”, page 54

⇒ “3.6.10 Refrigerant temperature sender G454 ”, page 55

3.6.1 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).

3.6.2 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).

48 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.6.3 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).

3.6.4 Connections with valve for refrigerant circuit switches

• Different threads for switches on high- and low pressure sides.

• 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

When removing and installing the valve core -C- with refrigerant circuit discharged, use e.g. adapter from socket - T10364- (tight‐ ening torque ⇒ page 42 ).

3.6.5 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- .

3. General information on refrigerant circuit 49

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

3.6.6 High-pressure sender - G65- and pres‐ sure sender for refrigerant circuit G805-

♦ -G65- is installed instead of the air conditioning system pres‐

sure switch - F129- or the refrigerant pressure and tempera‐ ture sender - G395- .

♦ On some vehicles from a certain version and production date

onwards, -G805- replaces -G65- .

♦ When voltage is applied, one version of -G65- generates a

square-wave signal and the other generates a data telegram. This signal changes with the pressure in the system. The other version and -G805- exchange information with the corre‐ sponding control unit via the data bus (e.g. via the “LIN bus”) when voltage is applied ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ -G65- is installed e.g. in the Audi A3 2005> and the Audi Q3.

It transmits its measured values as square-wave signals to the corresponding control unit (e.g. to the air conditioning system control unit - J301- or the Climatronic control unit - J255- ). G65- is installed e.g. in the Audi Q7 2016>. It transmits its measured values via a “LIN bus” ⇒ Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault Finding” function for air con‐ ditioner) and ⇒ Current flow diagrams, Electrical fault finding and Fitting locations.

♦ -G805- is installed e.g. in the Audi A3 2013>. It exchanges

information with the corresponding control unit over a data bus (e.g. in the Audi A3 with the air conditioning system control unit

- J301- or the Climatronic control unit - J255- ). ⇒ Current flow diagrams, Electrical fault finding and Fitting locations

♦ There are different versions of the refrigerant pressure and

temperature sender - G395- , the pressure sender for refrig‐ erant circuit - G805- and the high-pressure sender - G65- ; depending on the version, they can currently only be distin‐ guished by the part number. Therefore pay attention to the correct assignment when renewing the components (part number ⇒ Electronic parts catalogue ). Reason: These two senders emit different signals, and the relevant control units can only evaluate the signal to which they have been matched ⇒ Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault Finding” function for air conditioner), and ⇒ Heating, air con‐ ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ -G65- and -G805- transmit only the measured value for the

pressure in the refrigerant circuit to the connected control unit.

-G395- transmits the measured value for the pressure in the refrigerant circuit and the measured temperature to the con‐ nected control unit. Even if only the pressure signal is evalu‐ ated for a vehicle, a vehicle in which -G65- or -G805- is intended to be installed must not be fitted with a -G395- ⇒ Electronic parts catalogue .

♦ The control units downstream (radiator fan control unit, engine

control unit, operating and display unit for front air conditioning system - E87- or Climatronic control unit - J255- etc.) use this signal to calculate the pressure in the refrigerant circuit; the control units then actuate the radiator fans, motor and air con‐ ditioning system magnetic clutch - N25- accordingly or modify the activation of the air conditioner compressor regulating valve - N280- ⇒ Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault Finding” function) and ⇒ Heating, air condition‐ ing; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Work‐ shop Manual).

50 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

3.6.7 Refrigerant pressure and temperature sender

There are different versions of these senders with different func‐ tions and designations. For the exact designation, assignment and information on the corresponding function, refer to ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

WARNING

Risk of injury (frostbite).

Refrigerant may escape if the refrigerant circuit has not been discharged.

There are different versions of these senders (sender for a connection on the refrigerant circuit with or without valve) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐ hicle-specific Workshop Manual).

♦ Before loosening the bolt securing the sender, check the

version of the sender ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ With a sender for connecting to a refrigerant circuit without

valve. Extract the refrigerant before undoing the threaded joint. Renewed evaporation may create pressure in the refrigerant circuit if the sender is not removed within 10 minutes following extraction. Extract refrigerant again.

Senders for a connection with valve at refrigerant circuit

Note

♦

There are different versions of these senders with different functions and designations. For example, the refrigerant pres‐ sure and temperature sender - G395- (as illustrated below) is installed in the Audi A4, Audi Q5 and Audi Q5 hybrid ⇒ Heat‐ ing, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehiclespecific Workshop Manual).

♦

Different designations, depending on the function and vehicle ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

3. General information on refrigerant circuit 51

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Possible designations for these senders

♦ Refrigerant pressure and temperature sender - G395- (e.g. on

the Audi Q5 hybrid)

♦ High-pressure sender - G65- (e.g. on the Audi A4)

♦ Pressure sender for refrigerant circuit - G805- (e.g. on the Audi

A3 e-tron)

Note

The pressure sender for refrigerant circuit - G805- is installed e.g. instead of the high-pressure sender - G65- or the refrigerant pres‐ sure and temperature sender - G395- ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐ ual).

♦ There are different versions of the refrigerant pressure and

♦ When voltage is applied, the refrigerant pressure and temper‐

ature sender - G395- (and the pressure sender for refrigerant circuit - G805- ) exchange information with the corresponding control unit via the data bus (e.g. “LIN bus”). The correspond‐ ing control unit uses this information to calculate the pressure (and temperature) in the refrigerant circuit; any faults detected are signalled to the control unit.

♦ -G395- transmits the measured value for the pressure in the

refrigerant circuit and the measured temperature to the con‐ nected control unit. -G805- transmits only the measured value for the pressure in the refrigerant circuit to the connected con‐ trol unit. Even if only the pressure signal is evaluated on most vehicles, a vehicle in which a -G395- is intended to be installed must not be fitted with a -G805- ⇒ Electronic parts catalogue .

♦ The temperature measured by the refrigerant pressure and

temperature sender - G395- differs from the actual tempera‐ ture of the refrigerant in the refrigerant circuit due to the design of -G395- and the fitting location. Therefore it is currently not evaluated by all control units and used for air conditioner con‐ trol ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦ This information is used, for example, by the operating and

display unit ( Climatronic control unit - J255- ) or the onboard supply control unit - J519- to calculate the pressure in the re‐ frigerant circuit and to actuate the control units downstream (radiator fan control unit, engine control unit etc.) by way of the data bus. These control units then activate e.g. the air condi‐ tioning system magnetic clutch - N25- , the radiator fans and the motor accordingly ⇒ Vehicle diagnostic tester , “Self-di‐ agnosis” or “Guided Fault Finding” function and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

52 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Senders for a connection without valve at refrigerant circuit

Note

♦

There are different versions of these senders with different functions and designations. For example, the refrigerant pres‐ sure and temperature sender - G395- (as illustrated below) is installed in the Audi Q7 e-tron ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

Different designations, depending on the function and vehicle ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

Possible designations for these senders

♦ Refrigerant pressure and temperature sender - G395- (e.g. on

the Audi Q7 e-tron)

♦ Refrigerant pressure and temperature sender 2 - G826- (e.g.

on the Audi Q7 e-tron)

♦ Refrigerant pressure and temperature sender 3 - G827- (e.g.

on the Audi Q7 e-tron)

There are different versions of these senders -A-; depending on the version, they can currently only be distinguished by the part number or by the printed designation -B- if the part number is the same. Therefore pay attention to the correct assignment when renewing the components; for part number and designation, refer to ⇒ Electronic parts catalogue and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐ ual).

When voltage is applied, these senders exchange information with the corresponding control unit via the data bus (e.g. via the “LIN bus”). The corresponding control unit uses this information to calculate the pressure (and temperature) in the refrigerant cir‐ cuit; any faults detected are signalled to the control unit ⇒ Vehicle diagnostic tester (“Guided Fault Finding”).

The corresponding control unit uses this information to calculate the pressure in the refrigerant circuit and activates downstream control units or components (control unit for radiator fan, pumps, valves etc.) via the data bus according to requirements ⇒ Vehicle diagnostic tester (“Guided Fault Finding”) and ⇒ Heating, air con‐ ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Work‐ shop Manual).

3. General information on refrigerant circuit 53

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3.6.8 Air conditioner compressor regulating valve - N280-

The regulating valve is installed in the air conditioner compressor. It is activated by the operating and display unit for front air con‐ ditioning system - E87- , the air conditioning system control unit J301- 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 ; Refrigerant circuit (vehiclespecific Workshop Manual). The regulating valve influences the pressure on the low-pressure side and thus regulates the tem‐ perature in the evaporator.

Note

The air conditioner compressor regulating valve - N280- is part of the air conditioner compressor and cannot be renewed separately on all air conditioner compressors ⇒ Electronic parts catalogue and

⇒ “9.1.8 Removing/installing and renewing air conditioner com‐ pressor regulating valve N280 ”, page 269 .

3.6.9 Air conditioner compressor speed send‐ er - G111-

Inductive sender

The sender pulses (4 per compressor revolution) and the engine speed enable the operating and display unit for front air condi‐ tioning system - E87- or the Climatronic control unit - J255- to 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

♦

This component is installed in Audi vehicles with compressor drive via poly V-belt and Zexel compressor ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

The logo of the compressor manufacturer “Zexel” attached to the air conditioner compressor was modified from “Zexel” to “Valeo” from year of production 2006 onwards (change in manufacturer's name).

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3.6.10 Refrigerant temperature sender - G454-

The refrigerant temperature sender (with a temperature-sensitive resistor) is installed, for example, in the high-pressure line near the air conditioner compressor (only for certain vehicles manu‐ factured within a specific period, e.g. on Audi Q7 2007>).

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

♦

Installed e.g. in Audi Q7 with certain engines ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Current flow diagrams, Electrical fault finding and Fitting locations.

♦

The operating and display unit ( Climatronic control unit J255- ) evaluates the pressure and the temperature in the refrigerant circuit and switches off the air conditioner com‐ pressor if the temperature increases above the value stored for this pressure ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault Finding” function for air conditioner).

3.7 Electrical components not installed in refrigerant circuit

⇒ “3.7.1 Radiator fan control unit J293 ”, page 55

3.7.1 Radiator fan control unit - J293-

This control unit switches the magnetic clutch and thus the air conditioner compressor on and off. It switches the radiator fans and calculates the pressure in the refrigerant circuit on vehicles with a high-pressure sender - G65- . Refer to ⇒ Current flow dia‐ grams, Electrical fault finding and Fitting locations and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

3.8 Pressures and temperatures in refriger‐ ant circuit

Caution

♦ When working on the refrigerant circuit, observe generally

valid safety precautions and pressure vessel regulations.

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).

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

On vehicles with an electrical air conditioner compressor - V470- , the pressure in the refrigerant circuit (high-pressure and lowpressure sides) is regulated via the speed of the air conditioner compressor.

On vehicles with an electrical air conditioner compressor - V470where the air conditioner is used not only to cool the passenger compartment but also to cool high-voltage system components and as a heat pump to heat the passenger compartment, different conditions, pressures and temperatures apply in the refrigerant circuit (e.g. on the Audi Q7 e-tron) ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐ ual).

For this reason, the values given in the following table are for ref‐ erence only. 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 locations of the pressure gauge connections ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

At 20 °C with the engine not running, the pressure in the refrig‐ erant circuit is 4.7 bar ⇒ page 7 (vapour pressure table).

Note

⇒ “3.8.1 Refrigerant circuit with expansion valve”, page 56

⇒ “3.8.2 Refrigerant circuit with restrictor and reservoir”, page 58

3.8.1 Refrigerant circuit with expansion valve

Note

Only applies with restrictions to vehicles with an electrical air con‐ ditioner compressor - V470- .

HP – High-pressure side of refrigerant circuit (HD in illustration)

LP – Low-pressure side of refrigerant circuit (ND in illustration)

Component State of refrigerant Pressure (bar) Temperature in degrees

-1- Evaporator, from inlet to outlet

-2- Expansion valve Liquid, expanded to va‐

-3- High-pressure switch / high-pressure sender

Vapour

pour

Liquid approx. 14 bar approx. +55 °C

approx. 1.2 bar1)1 approx. -7 °C 2)2

approx. 14 bar approx. +55 °C (high-

centigrade

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

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Component State of refrigerant Pressure (bar) Temperature in degrees

-4- Service connection

Liquid approx. 14 bar approx. +55 °C (high-pressure side) and

-5- Receiver

-6- Condenser From gas (at inlet) via va‐

pour to liquid (at outlet)

-7- High-pressure safety

Gas approx. 14 bar approx. +65 °C valve and

-8- Air conditioner com‐ pressor (HP side)

-9- Air conditioner com‐

Gas pressor (low-pressure side)

-10- Damping chamber

Gas (not fitted on all vehicles) and

-11- Service connection (low-pressure side)

centigrade

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

inlet) to approx. +55 °C (at outlet)

approx. 1.2 bar1)1 approx. -1 °C 2)2

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 applies however only within the rated range of the air conditioner compressor; if the rated range of the air conditioner compressor is exceeded, the pressure will increase

⇒ page 183 .

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 183 .

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 side 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 version of the refrigerant circuit, a compo‐ nent with internal heat exchanger may be fitted (e.g. a refrig‐ erant line with internal heat exchanger is installed in the Audi A4 2008 > and in the Audi A5 Coupé 2008 >). In the internal heat exchanger, the hot refrigerant (liquid) flowing through the high-pressure side gives off energy to the cold refrigerant (gaseous or vaporous) flowing through the low-pressure side, thus enhancing the efficiency of the air conditioner

⇒ page 35 .

Arrows show direction of refrigerant flow.

HP – High-pressure side of refrigerant circuit (HD in illustration)

LP – Low-pressure side of refrigerant circuit (ND in illustration)

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1 - Evaporator

2 - Expansion valve

3 - High-pressure switch / highpressure sender

❑ Different versions de‐

pending on vehicle

4 - Service connection (highpressure side)

5 - Receiver

❑ Different versions de‐

pending on vehicle

6 - Condenser

7 - High-pressure safety valve

8 - Air conditioner compressor (high-pressure side)

9 - Air conditioner compressor (low-pressure side)

10 - Damping chamber

❑ Not fitted on all vehicles

11 - Service connection (lowpressure side)

3.8.2 Refrigerant circuit with restrictor and reservoir

HP – High-pressure side of refrigerant circuit (HD in illustration)

LP – Low-pressure side of refrigerant circuit (ND in illustration)

Component State of refrigerant Pressure (bar) Temperature in degrees

centigrade

-1- Air conditioner com‐ pressor (high-pressure side)

-2- Condenser From gas to vapour to liq‐

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

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

-5- Reservoir Gas

-6- Air conditioner com‐ pressor (low-pressure side)

The pressures on the low-pressure side are maintained at approx. 2 bar absolute (corresponding to approx. 1 bar gauge) by the

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

Gas

side greater than 1.0 bar

end warmer than -4 °C

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“regulating” air conditioner compressor even at varying engine speeds. This applies however only within the rated range of the air conditioner compressor ; if the rated range of the air condi‐ tioner compressor is exceeded, the pressure will increase

⇒ page 183 .

Note

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

Arrows show direction of refrigerant flow.

HP – High-pressure side of refrigerant circuit (HD in illustration)

LP – Low-pressure side of refrigerant circuit (ND in illustration)

1 - Air conditioner compressor (high-pressure side)

2 - Condenser

3 - Restrictor

4 - Evaporator

5 - Reservoir

6 - Air conditioner compressor (low-pressure side)

3. General information on refrigerant circuit 59

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3.9 Tests and measurements performed with pressure gauge

Pressure gauge scales

1 - Temperature scale for refrigerant R134a CF3– CH2F or

CH2F– CF3

2 - Pressure scale

Note

Pressure gauges may have one or more temperature scales in addition to the pressure scale. The scale values for R134a are assigned according to the vapour pressure table. As different re‐ frigerants develop different vapour pressures at the same tem‐ perature, there is a temperature scale for each refrigerant.

⇒ “3.9.1 Tests and measurements which can be performed using pressure gauges”, page 60

3.9.1 Tests and measurements which can be performed using pressure gauges

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 applies in a refrigerant circuit containing liquid or vapour, but not gas. In gaseous form, the temperature is approx. 10 °C to 30 °C higher than the pressure gauge reading.

Detection of refrigerant in a closed vessel

In a closed vessel or in the refrigerant circuit, refrigerant R134a is present 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.

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Note

The relationship between pressure and temperature no longer applies if no liquid is present and f the pressure is only built up by gas.

3.10 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 cleaning the refrigerant circuit (flushing it with refrigerant R134a) ⇒ page 88 .

⇒ “3.10.1 Classification of extraction systems”, page 61

⇒ “3.10.2 Charging systems that do not require a permit”, page 62

3.10.1 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 that do not require a permit (Group “3”) but which should only be operated by qualified personnel. Instructions for the operation and service of the devices may 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. In accordance with § 3 Para. 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 (On the other hand, a permit is required for the system to fill a pressurised gas container for transfer to another party from this pressurised container, and the permit requires an examination.)

3. General information on refrigerant circuit 61

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3.10.2 Charging systems that do not require 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 high-pressure safety valve for surplus refrigerant for internal use.

Various technical regulations (e.g. TRGS 400, TRGS 402, TRGS 407, TRGS 510, TRGS 725/TRBS 3145) must be noted when filling compressed gases into other compressed-gas vessels.

3.11 Repair notes for refrigerant circuit

WARNING

♦ When working on the refrigerant circuit, observe generally

valid safety precautions and pressure vessel regulations.

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 on

⇒ page 361 .

• Requires compliance with the basic instructions for use of leak

detectors ⇒ page 161 .

• Requires expert knowledge.

Note

Releasing refrigerant into the environment is prohibited

⇒ page 63 (laws and regulations).

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4 Laws and regulations

Note

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

⇒ “4.1 Laws and regulations”, page 63

4.1 Laws and regulations

By now the effects of climate change can be seen across the globe. Climate protection is thus one of the most important prob‐ lems to be tackled. Solving this problem does however represent 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 refrigerant R134a, due to their high global warming po‐ tential.

A number of laws of relevance to the automotive 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. 1005/2009

♦ Regulation (EC) no. 2037/2000

♦ Regulation (EC) no. 842/2006 (from 01.01.2015 onwards: reg‐

ulation (EU) no. 517/2014)

♦ 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.

However, the following is generally applicable:

Operation, maintenance, shut-down, take-back obligation

♦ With regard to the operation, repair and shut-down of products

containing refrigerants (which do not comply with the state of the art), it is prohibited to allow 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.

4. Laws and regulations 63

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♦ Distributors of the substances and compounds specified in the

regulations listed above are obliged to take back such sub‐ stances and compounds after use or to ensure that these are taken back by a third party specified by the distributor.

♦ 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.

Various technical regulations (e.g. TRGS 400, TRGS 402, TRGS 407, TRGS 510, TRGS 725/TRBS 3145) must be noted when handling and filling compressed gases.

Note

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

♦ TRGS 400 (Risk assessment for activities involving hazardous

substances)

♦ TRGS 402 (Identification and assessment of the risks from

activities involving hazardous substances: inhalation expo‐ sure)

♦ TRGS 407 (Activities involving gases - risk assessment)

♦ TRGS 510 (Storage of hazardous substances in non-station‐

ary containers)

♦ TRBS 3145/TRGS 725 (Non-stationary compressed-gas ves‐

sels - filling, keeping, in-house transportation, emptying)

Note

♦

The technical regulations for compressed gases (TRG), haz‐ ardous substances (TRGS) and workplace safety (TRBS) re‐ flect the current state of the art in occupational safety and hygiene as well as other ergonomic findings for the provision and use of work equipment as well as for the operation of sys‐ tems requiring supervision and/or for activities involving haz‐ ardous substances.

♦

The specified technical regulations apply to Germany; in other countries, rules and regulations differing from these may ap‐ ply.

Various technical regulations (e.g. TRGS 400, TRGS 402, TRGS 407, TRGS 510, TRGS 725/TRBS 3145) must be noted when handling and filling compressed gases.

♦ General provisions for charging systems

♦ Definition of terms and explanatory notes

♦ Constructing and operating charging systems

Charging systems

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♦ Does not apply to vehicle manufacturers or workshops.

♦ Charging systems are systems for filling mobile compressed-

gas vessels. The charging system includes the premises and facilities concerned.

♦ 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.

Employees and employee instruction

– Employees are to be given instruction on the following topics

before 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 TRGS and TRBS

• Procedures in the event of malfunction, damage and accidents

• The use of fire-extinguishing and protective equipment

• 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 per‐ sons:

♦ 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.

Filling compressed-gas vessels (other technical regulations not mentioned here may apply to vessels from other countries and filling of these vessels).

♦ 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 ≥ -10°C (tc = critical temperature) - the maximum permissible charging weight in line with TRGS must be marked on the vessel prior to con‐ nection 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. The charged vessels must be checked by way of ran‐ dom pressure measurements to determine possible overfill‐ ing.

4. Laws and regulations 65

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♦ 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 must be weighed during filling and subsequently subjected to a weight check on special scales to detect pos‐ sible overfilling. Scales used for this purpose must be calibra‐ ted.

♦ 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 TRGS apply to filling workmen's cylinders with liquefied gas.

♦ Different TRGS apply to vessels in vehicles:

– For gases with tc ≥ +70°C.

– For technical gas mixtures with tc ≥ +70°C.

– Liquefied extremely low-temperature compressed gases 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 temperature of the charge. When filling volumetrically, it must be ensured that the per‐ missible charge weight indicated on the vessel is not excee‐ ded. To determine possible overfilling, the charged vessels are to be checked gravimetrically on calibrated scales or volu‐ metrically, provided that the compressed gases are not highly toxic. Volumetric checking requires the use of appropriate equipment with completely separate charging and checking devices.

♦ Charging and check measurements must be performed by

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

♦ Overfilled vessels must be discharged immediately and safely

until the permissible filling quantity is reached. The com‐ pressed-gas fill must then be determined again.

♦ Certain parts of TRGS 407 do not apply or only apply to a

limited extent to vessels for liquefied, extremely low-tempera‐ ture compressed gases which are neither flammable nor toxic; this does not affect the provisions of road traffic legislation.

♦ When filling compressed gas vessels with liquefied gases at

charging temperatures ≤ -20°C, the compressed gas vessel (if the vessel material has not been tested for temperatures ≤

-20°C) is not to be released from the charging system for transportation until the vessel wall temperature is ≤ +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 must be transferred to marked recycling cylinders, 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 machine oils from systems with halogenated hy‐ drocarbons must be disposed of as waste requiring particular care. They are not to be mixed with other oils or substances.

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Proper storage and disposal must be ensured in line with local regulations. 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) ⇒ Audi-ServiceNet, HSO Environmental Protection .

⇒ “4.1.1 Conversion of an R12 refrigerant circuit to an R134a re‐ frigerant circuit and servicing (retrofit)”, page 67

⇒ “4.1.2 Keeping refrigerant records”, page 67

4.1.1 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 conversion, various components of the re‐ frigerant circuit must be renewed.

♦

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).

4.1.2 Keeping refrigerant records

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.

4. Laws and regulations 67

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5 Refrigerant circuit

⇒ “5.1 Important repair notes for air conditioning systems”, page 68

⇒ “5.2 Converting refrigerant circuits from refrigerant R12 to re‐ frigerant R134a ”, page 68

⇒ “5.3 Working with the air conditioner service station”, page 69

⇒ “5.4 Blowing out refrigerant circuit with compressed air and ni‐ trogen ”, page 84

⇒ “5.5 Cleaning (flushing) refrigerant circuit with refrigerant R134a”, page 88

⇒ “5.6 Tracing leaks in refrigerant circuit ”, page 161

5.1 Important repair notes for air condition‐ ing systems

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

frigerant R134a if certain prerequisites are satisfied

⇒ page 67 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 into contact with

the refrigerant should only 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.

• Within the engine compartment, on the bonnet catch striker

plate or in the plenum chamber there is an information plate which states what refrigerant is used.

• Never mix different refrigerants.

Note

When working on the refrigerant circuit, please observe the in‐ formation given in the section “Basic rules for working on refrig‐ erant circuit”

⇒ “2.12 Basic rules for working on refrigerant circuit”, page 17 .

5.2 Converting refrigerant circuits from re‐ frigerant R12 to refrigerant 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 printed form).

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Air conditioner with refrigerant R134a - Edition 05.2019

5.3 Working with the air conditioner service station

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.

5. Refrigerant circuit 69

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

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 objects to the use of chemical substances (sealing addi‐ tives) for sealing leaks in refrigerant circuits.

♦

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 no longer be completely removed from the components (not even by cleaning/flushing with refrigerant R134a).

♦

Chemical substances (sealing additives) used to seal leaks in refrigerant circuits usually cannot be detected from the out‐ side; mostly the stickers that are supposed to be attached to identify these chemical substances are missing. Therefore, act with caution when working on a vehicle whose past you are not familiar with.

♦

On the accessories market, vessels with integrated filters are available which are supposed to intercept these chemical sub‐ stances (additives used to seal leaks). As Audi are not aware of the composition and thus the physical and chemical prop‐ erties 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 side of the vehicle refrigerant circuit (the air con‐ ditioner service station is not to be attached to the service connection on the high-pressure side 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 if you have good reason to believe that such substances have been added), the customer (vehicle owner) must be notified of the following:

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Air conditioner with refrigerant R134a - Edition 05.2019

♦ The air conditioner refrigerant cannot be extracted on account

of the substances added (sealing additives), as these could 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 conditioning system can only be properly repaired by

renewing all the refrigerant circuit components which have come into contact with the sealing additive. The sealing addi‐ tive may already have damaged certain refrigerant circuit com‐ ponents (e.g. the air conditioner compressor regulating valve

- N280- ) or lead to damage and subsequent failure shortly after renewed start-up. Furthermore, sealing additive deposits may subsequently come loose in the refrigerant circuit com‐ ponents and then cause the air conditioner to fail again (full cleaning of these components with workshop equipment is currently not possible).

Work on the air conditioner refrigerant circuit

⇒ “5.3.1 Important notes for working with the air conditioner serv‐ ice station”, page 71

⇒ “5.3.2 Connecting air conditioner service station for measuring and testing”, page 72

⇒ “5.3.3 Discharging refrigerant circuit with air conditioner service station”, page 73

⇒ “5.3.4 Evacuating refrigerant circuit with air conditioner service station”, page 75

⇒ “5.3.5 Charging refrigerant circuit with air conditioner service station”, page 80

⇒ “5.3.6 Starting up air conditioner after charging”, page 81

⇒ “5.3.7 Pouring refrigerant into reservoir (charging cylinder or storage vessel) of air conditioner service station”, page 83

⇒ “5.3.8 Discharging air conditioner service station”, page 83

5.3.1 Important notes for working with the air conditioner service station

Observe the following in order to operate the air conditioner serv‐ ice stations, currently available air conditioner service stations ⇒ Electronic parts catalogue (Tools; Workshop equipment/tools; Air conditioning/heating):

– The fitted filter and dryer must be renewed by no later than

when the operational time specified in the related operating instructions has been reached.

– If an air conditioner service station is also used to clean (flush)

the refrigerant circuit, the dryers and filters fitted must be re‐ newed more frequently ⇒ page 84 .

– Use only refrigerant oils which are also approved for the ve‐

hicle-specific refrigerant circuit (if applicable, add the refriger‐ ant 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, discharge the air conditioner service station

⇒ page 178 , clean the system if necessary and renew the

filters, dryers and refrigerant oil.

5. Refrigerant circuit 71

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

turned to the refrigerant supplier in so-called recycling cylin‐ ders for treatment or environmentally friendly disposal (differ‐ ent or additional regulations may apply in individual 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, for currently available air conditioner serv‐ ice stations) ⇒ Electronic parts catalogue (Tools; Workshop equipment/tools; Air conditioning/heating).

♦ Air conditioner service stations which transfer extracted re‐

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

5.3.2 Connecting air conditioner service sta‐ tion for measuring and testing

• Work procedure may vary depending on the type of tools se‐

lected; therefore it is important to observe the tool-specific operating instructions.

Note

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

The filler hoses should be connected as follows to prevent air or moisture from entering into the refrigerant circuit:

– On vehicles with high-voltage system, switch off (deactivate)

auxiliary air conditioner function ⇒ Owner's Manual and ⇒ Infotainment/MMI Operating Manual .

– Switch off ignition.

– Connect air conditioner service station to power supply.

– Unscrew sealing caps from service connections / connections

with valve ⇒ Heating, air conditioning; Rep. gr. 87 ; Refriger‐ ant circuit (vehicle-specific Workshop Manual).

– Evacuate filler hoses if necessary.

– Connect quick-release coupling to service connection of re‐

frigerant 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.

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Air conditioner with refrigerant R134a - Edition 05.2019

– Compare the values determined to the specified measured

values ⇒ page 183 .

– Before detaching quick-release coupling, close it by screwing

out handwheel.

Vehicles with one service connection only:

Note

Screw valve adapters - V.A.G 1785/9- , -V.A.G 1785/10- or adapt‐ er set - V.A.G 1786- onto refrigerant circuit connections with valve and bleed filler hoses while connecting to adapters (faintly audible escape of refrigerant gas is permitted) ⇒ page 178 .

– The filler hose must be fitted with a valve opener for opening

valve in valve adapter.

On vehicles with high-voltage system and additional air condi‐ tioner functions (e.g. on the Audi Q7 e-tron):

Note

On vehicles with the “heat pump” and/or “high-voltage battery cooling” function, high pressure is not available at the service connection on the high-pressure side in all air conditioner oper‐ ating modes. On these vehicles, the pressure in the refrigerant circuit on the high-pressure side can only be measured via the pressure/temperature senders installed in the refrigerant circuit (depending on the air conditioner operating mode) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Vehicle diagnostic tester (“Guided Fault Finding”).

To check the various functions of these air conditioners:

– On the vehicle diagnostic tester, select the corresponding

function (“passenger compartment cooling”, “heat pump op‐ eration” or “high-voltage battery cooling”) and perform the function according to requirements ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

– On the vehicle diagnostic tester, select and read out the meas‐

urements from the various pressure/temperature senders in‐ stalled in the refrigerant circuit ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

5.3.3 Discharging refrigerant circuit with air conditioner service station

• Work procedure may vary depending on the type of tools se‐

lected; it is therefore important to observe the tool-specific operating instructions.

• The refrigerant circuit must be discharged if you intend to re‐

move parts of the refrigerant circuit, if there is any doubt about the quantity of refrigerant in the circuit or if safety precautions require you to do so.

• 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.

Discharging:

– On vehicles with high-voltage system, switch off (deactivate)

auxiliary air conditioner function ⇒ Owner's Manual and ⇒ Infotainment/MMI Operating Manual .

5. Refrigerant circuit 73

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

– Switch off ignition.

– Connect air conditioner service station to vehicle service con‐

nections according to operating instructions (refer to vehiclespecific refrigerant circuit) and start up service station ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐ hicle-specific Workshop Manual).

Additionally on vehicles with electrically operated valves in the refrigerant circuit which are not open when the system is de-ener‐ gised (e.g. on the Audi Q7 e-tron):

Note

On vehicles with high-voltage system and additional air condi‐ tioner functions (“heat pump operation” or “high-voltage battery cooling”), valves which are not open when the system is de-ener‐ gised may be fitted in the refrigerant circuit. These valves are opened and closed e.g. via stepper motors and are not activated after the ignition is switched off. However, for the refrigerant circuit to be discharged fully, evacuated correctly and filled there must be no separated areas; these valves must therefore be opened before performing such work ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual), and ⇒ Vehicle diagnostic tester (“Guided Fault Finding”).

– Use the vehicle diagnostic tester to open the electrically acti‐

vated valves which are not open when the system is deenergised ⇒ Vehicle diagnostic tester (“Guided Fault Find‐ ing”).

All vehicles:

– Drain the refrigerant circuit with the air conditioner service sta‐

tion in line with the corresponding operating instructions.

Caution

Risk of air conditioner compressor damage if the refrigerant circuit is empty

Never start the engine when the refrigerant circuit is empty.

♦ Depending on the version of the air conditioner service

station, the pressure in the refrigerant circuit may be less than 1 bar absolute following drainage.

♦ Depending on the version, the air conditioner compressor

may be damaged by running it when the pressure in the refrigerant circuit is low.

♦ Never start the engine if the pressure in the refrigerant

circuit is below ambient pressure.

WARNING

Risk of injury (frostbite).

Refrigerant may escape if the refrigerant circuit has not been discharged.

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Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

It is impossible to exclude the possibility that refrigerant oil may be extracted from the refrigerant circuit along with the refrig‐ erant. To ensure air conditioner compressor lubrication, the refrigerant oil in the circuit must be topped up with fresh oil

⇒ page 276 .

♦

On vehicles fitted with an air conditioner compressor without magnetic clutch (with air conditioner compressor regulating valve - N280- ), the engine should not be run for longer than absolutely necessary with the refrigerant circuit empty; avoid high engine speeds (with air conditioner compressor always in operation).

♦

On vehicles with an air conditioner compressor without a mag‐ netic clutch, the engine should only be started following the complete assembly of the refrigerant circuit (avoid high engine speeds).

♦

Depending on the version of the air conditioner compressor, there may be a valve on the high-pressure side of the com‐ pressor which prevents liquid refrigerant from flowing back into the compressor after the air conditioner has been switched off. If an air conditioner compressor with such a valve is installed in a vehicle with a refrigerant circuit with an expansion valve, it may take a relatively long time before the pressure in the high-pressure side drops (the expansion valve is cold and the pressure in the low-pressure side increases rapidly after the compressor is switched off; the expansion valve is closed and the refrigerant can only flow slowly to the low-pressure side). If the air conditioner compressor is switched on (or the refrig‐ erant circuit is discharged via the low-pressure side), the pressure on the low-pressure side drops, the expansion valve is opened and the refrigerant can flow to the low-pressure side.

♦

The quantity of refrigerant R134a extracted as displayed by the air conditioner service station may differ from the amount actually extracted depending on the version of the air condi‐ tioner service station, the mode in which the air conditioner service station was last operated and the ambient temperature etc. The quantity of refrigerant extracted as displayed by the air conditioner service station is therefore only a guide to the amount of refrigerant actually extracted from the refrigerant circuit. Attention should also be paid to the operating instruc‐ tions and technical product description of the air conditioner service station.

If, after drainage, work not requiring the air conditioner service station is to be performed on the vehicle,

– disconnect the air conditioner service station from the refrig‐

erant circuit and switch it off.

If evacuating and re-charging refrigerant circuit after it is dis‐ charged, refer to ⇒ page 80 .

5.3.4 Evacuating refrigerant circuit with air conditioner service station

• The work procedure must always 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 276 .

• Quantity of refrigerant in air conditioner service station

checked

5. Refrigerant circuit 75

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

The refrigerant circuit must be evacuated (emptied of air) before it is charged with refrigerant. Moisture is also extracted from the circuit.

Leaks can be detected on evacuating the refrigerant circuit.

Evacuating:

Caution

♦ Do not start the engine during the evacuating procedure

and while 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.

– On vehicles with high-voltage system, switch off (deactivate)

auxiliary air conditioner function ⇒ Owner's Manual and ⇒ Infotainment/MMI Operating Manual .

– Switch off ignition.

– Connect air conditioner service station to power supply.

– Connect filler hoses of air conditioner service station to vehicle

refrigerant circuit with quick-release coupling adapter (refer to vehicle-specific refrigerant circuit) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (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 you intend to measured the pressure on only one side of the refrigerant circuit after charging the system (on vehicles with a service connection), use the valve adapter and filler hose with valve opener ⇒ page 178 .

Additionally on vehicles with electrically operated valves in the refrigerant circuit which are not open when the system is de-ener‐ gised (e.g. on the Audi Q7 e-tron):

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Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

On vehicles with high-voltage system and additional air con‐ ditioner functions (“heat pump operation” or “high-voltage bat‐ tery cooling”), valves which are not open when the system is de-energised may be fitted in the refrigerant circuit. These valves are opened and closed e.g. via stepper motors and are not activated after the ignition is switched off. However, for the refrigerant circuit to be discharged fully, evacuated correctly and filled there must be no separated areas; these valves must therefore be opened before performing such work ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-spe‐ cific Workshop Manual), and ⇒ Vehicle diagnostic tester (“Gui‐ ded Fault Finding”).

♦

– Use the vehicle diagnostic tester to open the electrically acti‐

vated valves which are not open when the system is deenergised ⇒ Vehicle diagnostic tester (“Guided Fault Find‐ ing”).

All vehicles:

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

frigerant 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 ⇒ Electronic parts cata‐ logue (Tools; Workshop equipment/tools; Air conditioning/heat‐ ing), the two green LEDs light at this pressure, for example.

– Switch off 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.

5. Refrigerant circuit 77

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

With V.A.G 1885 for example, for currently available air con‐ ditioner service stations ⇒ Electronic parts catalogue (Tools; Workshop equipment/tools; Air conditioning/heating), a cur‐ rent vacuum display (LED) is only obtained after pressing the

Evacuation

♦

If, with this air conditioner service station, the upper (green)

button again.

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. Only charge circuit if vacuum is maintained.

– If 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:

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Air conditioner with refrigerant R134a - Edition 05.2019

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 84 . If the leak is of large enough, the location of the leak can be found due to 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 e.g. a modified filler hose -A- (e.g. with a 5/8"-18 UNF thread, depending on thread on quick-release coupling adapt‐ er) and an appropriate adapter -B- ⇒ page 367 . To prevent moisture, oil and dirt from the workshop compressed air sys‐ tem from entering the air conditioner refrigerant circuit, also use a combination fine filter unit for the compressed air sys‐ tem, with an oil, dirt and water separator, as commonly used for painting systems. Install this unit between the compressed air system and the filler hose -A- ⇒ Electronic parts catalogue (Tools; Workshop equipment/tools; Air conditioning/heating).

♦

Using a pressure gauge set with nitrogen pressure reducer

-1- (max. reducing pressure: 15 bar), a compressed-gas cyl‐ inder -3- filled with nitrogen can be connected to the service connection (quick-release coupling adapter for service con‐ nections attached) at the closed refrigerant circuit

⇒ page 366 with a filler hose -2- (e.g. with a 5/8"-18 UNF

thread).

– 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.

♦ Only use pressure reducer 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 and again observe the vacuum display over a period

of hours. Only charge circuit if 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.

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

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

leak detector to locate and eliminate any leaks ⇒ page 163 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 165 .

– If necessary, discharge refrigerant circuit ⇒ page 73 .

– Evacuate refrigerant circuit and observe vacuum display again

over a period of hours. Only charge circuit if vacuum is main‐ tained.

5.3.5 Charging refrigerant circuit with air con‐ ditioner service station

Note

The entire refrigerant charge can be added to either the high or low-pressure side ⇒ page 276 .

• The work procedure must always 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 276 .

• 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 charging accuracy of the air condition‐ er service station may change.

– On vehicles with high-voltage system, switch off (deactivate)

auxiliary air conditioner function ⇒ Owner's Manual and ⇒ Infotainment/MMI Operating Manual .

– Switch off ignition.

– Evacuate refrigerant circuit with air conditioner service station

⇒ page 75 .

Additionally on vehicles with electrically operated valves in the refrigerant circuit which are not open when the system is de-ener‐ gised (e.g. on the Audi Q7 e-tron):

Note

– Use the vehicle diagnostic tester to open the electrically acti‐

vated valves which are not open when the system is deenergised ⇒ Vehicle diagnostic tester (“Guided Fault Find‐ ing”).

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Air conditioner with refrigerant R134a - Edition 05.2019

All vehicles:

– Unscrew the handwheel at the quick-release coupling adapter

(to close it).

– Allow refrigerant to flow into filler hose.

– Take the charging cylinder reading.

– Screw in the handwheel at the quick-release coupling adapter

(to open it) and charge with the specified quantity of refriger‐ ant.

– Switch off air conditioner service station.

On vehicles for which the Service Schedule specifies that the re‐ frigerant circuit must be drained/filled after a specific mileage:

– After performing the work, enter “air conditioner refilled” in the

appropriate field in the Service Schedule ⇒ Maintenance ta‐ bles and/or “Maintenance” manual.

Note

Draining and filling the refrigerant circuit is only specified as main‐ tenance work in the Service Schedule for certain vehicles (cur‐ rently e.g. for the Audi Q7 e-tron and Audi A6 e-tron).

5.3.6 Starting up air conditioner after charging

Note

♦

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

♦

If it has been removed, the electrically driven air conditioner compressor is to be started up, prior to initial commissioning of the air conditioner and following charging, by way of the “Basic setting, compressor run-in” function of the Guided Fault Finding routine ⇒ Vehicle diagnostic tester, “Guided Fault Finding” function for air conditioner and battery regulation . This guards the air conditioner compressor against damage caused for example by fluid lock when first switched on (any oil in the combustion chamber of the air conditioner compres‐ sor is forced out).

♦

The mechanically driven air conditioner compressor is driven via a belt or shaft by the engine. The electrically driven air conditioner compressor is driven via an electric motor attach‐ ed directly to the air conditioner compressor (e.g. on vehicles with hybrid drive).

5. Refrigerant circuit 81

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Starting up 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, i.e.

"Econ" or A/C off mode (version with no magnetic clutch with regulating valve).

– Wait for idling speed to stabilise.

– Switch on air conditioner compressor and operate system for

at least two minutes at idling speed.

– If necessary, check pressures in refrigerant circuit with air

conditioner service station.

– Switch off engine.

– Screw out handwheel on quick-release coupling adapter.

– Detach filler hoses from refrigerant circuit.

– Screw the sealing caps back on.

Starting up air conditioner with electrically driven air conditioner compressor

– Start up air conditioner compressor via “Basic setting, com‐

pressor run-in” function of Guided Fault Finding ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode for air con‐ ditioner and battery regulation .

Additionally on vehicles with electrically operated valves in the refrigerant circuit which are not open when the system is de-ener‐ gised (e.g. on the Audi Q7 e-tron):

– Via respective control unit, enable activation of electrically op‐

erated valves (for opening or closing) which are not open without current for air conditioner operation ⇒ Vehicle diag‐ nostic tester (“Guided Fault Finding”).

Note

On vehicles with high-voltage system and additional air condi‐ tioner functions (“heat pump operation” or “high-voltage battery cooling”), valves which are not open when the system is de-ener‐ gised may be fitted in the refrigerant circuit. These valves are opened and closed e.g. via stepper motors and are not activated after the ignition is switched off. However, for the refrigerant circuit to be discharged fully, evacuated correctly and filled there must be no separated areas; these valves must therefore be opened before performing such work. After completing work on the re‐ frigerant circuit, the valves which are activated e.g. via stepper motors must be re-activated via the corresponding control unit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehiclespecific Workshop Manual) and ⇒ Vehicle diagnostic tester in “Guided Fault Finding” mode.

All vehicles:

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

the air conditioner service station on completion of basic set‐ ting ⇒ page 72 .

– Screw out handwheel on quick-release coupling adapter.

– Detach filler hoses from refrigerant circuit.

– Screw the sealing caps back on.

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Air conditioner with refrigerant R134a - Edition 05.2019

5.3.7 Pouring refrigerant into reservoir (charg‐ ing cylinder or storage vessel) of air con‐ ditioner service station

• The work procedure must always 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).

WARNING

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

5.3.8 Discharging air conditioner service sta‐ tion

Note

♦

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

♦

Refrigerant cylinders filled with contaminated or used refrig‐ erant are termed “recycling cylinders ”.

♦

Always evacuate recycling cylinders before initial filling with refrigerant (if there is air in a refrigerant vessel it must not be filled with refrigerant).

♦

Do not mix various types of refrigerant (refrigerant mixtures cannot be recycled and must be disposed of). If there is any doubt about the composition of the contents of the container, the refrigerant recycling company must be informed.

5. Refrigerant circuit 83

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Caution

♦ Observe the applicable regulations, technical rules and

laws when charging recycling cylinders (compressed gas cylinders).

♦ Recycling cylinders must never be overfilled. If recycling

cylinders are overfilled, the gas cushion is too small to withstand the expansion of liquid caused by exposure to heat. There is a risk of bursting.

♦ For your own safety, only use recycling cylinders with a

built-in safety valve.

♦ Recycling cylinders must be weighed on calibrated scales

during the filling process. The maximum permissible ca‐ pacity is 75% (filling factor 0.75) of the filling weight indi‐ cated on the recycling cylinder (the possibility of refriger‐ ant oil entering the recycling cylinder along with the refrigerant cannot be ruled out).

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

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 clean (flush) the refrigerant circuit with refrigerant R134a or to blow it out with compressed air and nitrogen.

Note

♦

Blowing out the refrigerant circuit with compressed air and ni‐ trogen usually involves far more work than cleaning (flushing) with refrigerant R134a. Cleaning (flushing) with refrigerant R134a also provides far better cleaning of the components. Flushing should therefore 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 pipes 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 cleaning (flushing) with refrigerant R134a ⇒ page 88 .

♦

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).

84 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

WARNING

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

cylinder.

♦ Only use pressure reducer 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 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 desiccant cartridge in

the integrated receiver, this cartridge is to be removed.

Note

♦

On vehicles with condensers with an integrated receiver/des‐ iccant cartridge which cannot be renewed separately, the condenser must be renewed after it has been cleaned (flush‐ ed).

♦

Depending on the version, receivers on which the desiccant cartridge can be renewed separately may be provided with an additional filter element which may have to be renewed to‐ gether with the desiccant cartridge.

– 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 connecting pressure hose to refrigerant circuit,

refer to ⇒ page 178 .

Observe the following to prevent oil and moisture from the com‐ pressed-air system from entering the refrigerant circuit.

– The compressed air must be passed through a compressed-

air purifier to clean and dry it. Use is therefore to be made of filter and dryer for compressed air (included in scope of deliv‐ ery as tool for painting work).

– For refrigerant lines with thread or union nut at connection, use

adapters from adapter set - V.A.G 1785- ( adapter - V.A.G 1785/1- to adapter - V.A.G 1785/8- ) for connecting 5/8" -18 UNF filler hoses (some of these adapters are also contained in the adapter set for refrigerant circuits - VAS 6338/1- ).

– For refrigerant lines with no thread or union nut at connection

(for connecting adapters), use adapters from adapter set for refrigerant circuits - VAS 6338/1- or commercially available blow-out gun with rubber mouthpiece.

5. Refrigerant circuit 85

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

The refrigerant circuit is only to be blown out with compressed air and then nitrogen if no means of cleaning (flushing) the refrigerant circuit with refrigerant R134a are available or if flushing of individual components would involve too much work (blowing minor impurities and small quantities of mois‐ ture out of refrigerant pipes for example is not particularly timeconsuming).

♦

Compressed air/nitrogen emerging from components must be drawn off using an appropriate system (e.g. workshop extrac‐ tor).

The refrigerant circuit (or individual components) is/are to be blown out if no means of cleaning (flushing with refrigerant R134a) are available or if cleaning (flushing with refrigerant R134a) seems inappropriate

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

ponents

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

refrigerant circuit (pressure build-up due to moisture in refrig‐ erant 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 that there is moisture in the circuit.

– If it is uncertain how much refrigerant oil is in the refrigerant

circuit.

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

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

Note

For vehicles with an electrically driven air conditioner compressor, see the notes on renewing the electrical air conditioner compres‐ sor - V470- (damage to the air conditioner compressor electronics does not always mean that the refrigerant circuit has to be cleaned) ⇒ page 262

– If stipulated by the vehicle-specific Workshop Manual after re‐

newing certain components

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 cleaning (flushing) with refrigerant R134a ⇒ page 88 .

86 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

⇒ “5.4.1 Blowing out refrigerant circuit”, page 87

5.4.1 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- . Take special care not to damage the connections by crushing or scratching them when using an air pistol with a rubber end piece.

♦

The evaporator must be blown out via the connection for the low-pressure line (large diameter) after removing the expan‐ sion valve or restrictor.

♦

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

♦

Check expansion valve and renew if dirty or corroded.

♦

If dark, sticky deposits cannot be removed with compressed air, clean (flush) the components concerned with refrigerant R134a or renew.

♦

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

♦

After flushing, always renew receiver or reservoir and restric‐ tor. In the case of condensers fitted with a desiccant cartridge in the integrated receiver, this cartridge must be renewed.

♦

On vehicles with condensers with an integrated receiver/des‐ iccant cartridge which cannot be renewed separately or which are not available as a replacement part, the condenser must be renewed after cleaning (flushing) ⇒ Electronic parts cata‐ logue and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refriger‐ ant circuit (vehicle-specific Workshop Manual).

♦

After blowing out refrigerant circuit:

– Renew the following components (vehicle-specific): restrictor

and reservoir, expansion valve and receiver / desiccant car‐ tridge ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

– Depending on the problem, renew air conditioner compressor

⇒ Heating, air conditioning; Rep. gr. 87 ; Air conditioner com‐ pressor (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue , or drain off remaining refrigerant oil from air conditioner compressor (removed earlier) ⇒ page 258 (re‐ newing components of refrigerant circuit) and add specified quantity of new refrigerant oil again ⇒ page 317 (approved refrigerant oils and refrigerant oil capacities).

5. Refrigerant circuit 87

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

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 ; Re‐ frigerant circuit (vehicle-specific Workshop Manual) and

⇒ page 317 (approved refrigerant oils and refrigerant oil ca‐

pacities).

♦

If the air conditioner compressor is not supposed to be re‐ newed, the refrigerant oil quantity in the air conditioner com‐ pressor must be topped up in line with the specified capacity (pour out refrigerant oil and add the specified quantity to the air conditioner compressor or the refrigerant circuit again)

⇒ page 258 (Renewing refrigerant circuit components) and ⇒ page 317 (Approved refrigerant oils and refrigerant oil ca‐

pacities).

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

conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

– Evacuate and charge the refrigerant circuit as specified

⇒ page 75 and ⇒ page 80 .

– Start up air conditioner as specified ⇒ Heating, air condition‐

ing; Rep. gr. 87 ; Refrigerant circuit; Starting up air conditioner after charging refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ page 81 .

5.5 Cleaning (flushing) 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 clean (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 cleaned (flushed) and serviced by your workshop.

88 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

Audi objects to the use of chemical substances (sealing addi‐ tives) for sealing leaks in refrigerant circuits.

♦

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 affected (even by cleaning/flushing). Therefore the refrigerant circuit can only be serviced by renewing all components that have come into contact with the chemical substances.

♦

• 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 clean (flush) the refrigerant circuit with refrigerant R134a.

The refrigerant circuit is to be flushed:

– If there is any dirt or similar in the circuit.

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

refrigerant circuit (pressure build-up due to moisture in refrig‐ erant 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 that there is moisture in the circuit.

– If it is uncertain how much refrigerant oil is in the refrigerant

circuit.

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

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

Note

♦

For vehicles with an electrically driven air conditioner com‐ pressor, see the notes on renewing the electrical air condi‐ tioner compressor - V470- (damage to the air conditioner compressor electronics does not always mean that the refrig‐ erant circuit has to be cleaned) ⇒ page 262

♦

If a defective air conditioner compressor is replaced by a com‐ pressor from a different manufacturer, it is important to check whether the refrigerant oil already in the refrigerant circuit (from the removed compressor) is also approved for the new compressor. If a different refrigerant oil is approved for the new air conditioner compressor than for the removed compressor, the refrigerant circuit must be flushed ⇒ page 319 .

– If stipulated by the vehicle-specific Workshop Manual after re‐

newing certain components

5. Refrigerant circuit 89

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Tools required

♦ Air conditioner service station with flushing kit (these air con‐

ditioner service stations feature the additional function “Flush‐ ing refrigerant circuit” and the necessary flushing kit for refrigerant circuits) ⇒ Electronic parts catalogue (Tools; Work‐ shop equipment/tools; Air conditioning/heating).

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

⇒ page 111 and ⇒ Electronic parts catalogue (Tools; Work‐

shop equipment/tools; Air conditioning/heating).

Note

♦

If no air conditioner service station with flushing kit is available ⇒ Electronic parts catalogue (Tools; Workshop equipment/ tools; Air conditioning/heating) and depending on the version of the air conditioner service station being used, the refrigerant circuit can also be cleaned (flushed with refrigerant R134a) using the refrigerant circuit flushing kit ⇒ Electronic parts catalogue , (Tools; Workshop equipment/tools; Air condition‐ ing/heating) however this must then be performed manually.

⇒ page 96

♦

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 adapter set for refrigerant circuits - VAS 6338/1- also con‐ tains a short filler hose - VAS 6338/31- with 5/8 -18 UNF connections and a large inside diameter (commercially avail‐ able).

Preparations

– Discharge the refrigerant circuit ⇒ page 73 .

– Remove air conditioner compressor ⇒ Heating, air condition‐

ing; Rep. gr. 87 ; Air conditioner compressor (vehicle-specific Workshop Manual).

Vehicle with restrictor and reservoir

– Remove restrictor (vehicle-specific) and re-connect pipes ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐ hicle-specific Workshop Manual).

– Remove reservoir (vehicle-specific) and re-connect pipes (for

this purpose, use adapter and filler hose - VAS 6338/31- from adapter set for refrigerant circuits - VAS 6338/1- )

⇒ page 111 and ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerant circuit (vehicle-specific Workshop Manual).

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Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

Although it may be possible to flush the reservoir (depending on version), its large internal volume means that it holds too much liquid refrigerant. When this refrigerant is extracted the reservoir ices up severely, the refrigerant only evaporates very slowly and the extraction process takes too long.

♦

Although it may be possible to flush the receiver (depending on version; refer to the description for the specific vehicle), its large internal volume means that it may hold too much liquid refrigerant. When this refrigerant is extracted the reservoir ices up severely, the refrigerant only evaporates very slowly and the extraction process takes too long.

Vehicle with expansion valve and receiver

– Remove receiver (vehicle-specific; not necessary on all vehi‐

cles) and re-connect pipes (for this purpose, use adapter and filler hose - VAS 6338/31- from adapter set for refrigerant cir‐ cuits - VAS 6338/1- ) ⇒ page 111 and ⇒ Heating, air condi‐ tioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

Note

♦

Depending on the design, the receiver can be flushed (if nec‐ essary, remove desiccant cartridge installed in receiver)

⇒ page 111 and ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerant circuit (vehicle-specific Workshop Manual).

♦

If the receiver is attached to the condenser (e.g. on the Audi A3 from model year 2004 onwards), it must not be removed for flushing (its design makes it suitable for flushing, and it is only renewed after flushing) ⇒ page 111 and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

In the case of condensers with an integrated receiver / desic‐ cant cartridge which cannot be renewed separately or which are not available separately, the condenser is to be renewed after flushing. On these vehicles, renew the condenser to‐ gether with the receiver ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒ Electronic parts catalogue .

♦

– On vehicles with a desiccant cartridge in the receiver at the

condenser (vehicle-specific), remove the desiccant cartridge and re-seal the opening at the receiver ⇒ Heating, air condi‐ tioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Work‐ shop Manual).

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

with an adapter from the adapter set for refrigerant circuits VAS 6338/1- ⇒ page 111 and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

– On vehicles with one or more shut-off valves/non-return

valves, remove the valves and replace with suitable adapters (or hand shut-off valves) from the VW/Audi passenger vehicle adapter set - VAS 6338/1- ⇒ page 111 , ⇒ Heating, air con‐

5. Refrigerant circuit 91

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

ditioning; Rep. gr. 87 ; Refrigerant circuit (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 removed expansion valve can also be drilled open (the old expansion valve generally has to be renewed and is therefore no longer needed).

Note

♦

Item -3- can be disregarded.

♦

When drilling open the expansion valve, make sure that the openings -2- and -4- in the valve -1- are offset.

♦

If you do not do so, the sealing surface on the expansion valve

-1- could be damaged when drilling open the valve; the ex‐ pansion valve can then no longer be used for setting up the flushing circuit.

Drill open expansion valve.

92 Rep. gr.87 - Air conditioning system

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 05.2019

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 different de‐ signs. 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 must be separated from the circuit of the first evaporator and flushed in a separate operation ⇒ page 111 and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

Flushing

– Check that the air conditioner service station contains at least

6 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.

– Discharge the used oil container of the air conditioner service

station.

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

ditioner service station with an adapter to the low-pressure pipe to the air conditioner compressor (pipe with larger diam‐ eter) ⇒ page 111 .

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

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

– Connect the inlet of the refrigerant circuit flushing kit with an

adapter to the high-pressure pipe to the air conditioner com‐ pressor (pipe with smaller diameter) ⇒ page 111 .

5. Refrigerant circuit 93

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ... Air conditioner with refrigerant R134a - Edition 05.2019

Note

♦

The components are always (with the exception of the electric air conditioner compressor) flushed in the opposite direction to the refrigerant flow during air conditioner operation

⇒ page 98 .

♦

When flushing, impurities from the refrigerant circuit ingress into the refrigerant circuit flushing kit and the air conditioner service station, where they are retained in the built-in filters and dryer. Depending on the nature of the impurities, these components should be renewed more frequently in accord‐ ance with the operating instructions for the air conditioner service station or the refrigerant circuit flushing kit.

♦

Depending on the nature and severity of the contamination of the flushed refrigerant circuits, the filter in the refrigerant circuit flushing kit should be renewed at the latest after 5 to 10 flush‐ ing cycles (flushed vehicles). After flushing a severely conta‐ minated refrigerant circuit (the refrigerant oil from the refriger‐ ant circuit is black and viscous or there is a lot of swarf in the refrigerant circuit), renew the filter. In the case of such severely contaminated refrigerant circuits it is also appropriate to flush the circuit again after renewing the filter.

♦

Depending on the nature of the impurities, dirt (used refriger‐ ant oil and abrasion from air conditioner compressor) accu‐ mulates at the sight glass of the refrigerant circuit flushing kit. If applicable, clean this sight glass after flushing and flush the refrigerant circuit again in one operation as a check (one op‐ eration is then sufficient).

♦

Liquid refrigerant cannot be routed through the expansion valve, restrictor and desiccant bag of certain receivers at the necessary rate. Therefore remove these components and re‐ place them with adapters if applicable ⇒ Heating, air condi‐ tioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).

♦

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

⇒ page 111 .

– Connect flushing circuit in vehicle (depending on refrigerant

circuit) ⇒ page 111 .

Vehicles with 2 evaporators in refrigerant circuit:

Note

♦

The refrigerant circuit is cleaned in 2 flushing cycles (first the section with the evaporator in the front heater and air condi‐ tioning unit and then the section with the evaporator in the rear heater and air conditioning unit) ⇒ page 111 .

♦

On vehicles with two evaporators, the circuit to the second evaporator must be separated from the circuit of the first evap‐ orator and flushed in a separate operation ⇒ page 111 and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐ hicle-specific Workshop Manual).

94 Rep. gr.87 - Air conditioning system

audi Aire acondicionado Aire acondicionado

Specifications and Main Features

Frequently Asked Questions

User Manual