Carrier AC310, AC350 Operation And Service Instructions Manual

Transport Air Conditioning

OPERATION AND SERVICE

MODELS AC310 & AC350

Rooftop Air Conditioning Units

BT324 Carrier Sutrak Digital Display (CSDD)

280P/282P Electronic Thermostat

T--304 Rev A Change 07/09

for

With

or

OPERATION AND

SERVICE MANUAL

TRANSPORT

AIR CONDITIONING UNIT

MODELS

AC310 & AC350

ROOFTOP AIR CONDITIONING UNITS

*CSDD -- BT324 (*Carrier Sutrak Digital Display)

Electronic Thermostat -- 280P & 282P

TABLE OF CONTENTS

PARAGRAPH NUMBER Page

SAFETY SUMMARY Safety--1....................................................................

DESCRIPTION 1--1...............................................................................

1.1 INTRODUCTION 1--1.....................................................................

1.2 GENERAL DESCRIPTION 1--2.............................................................

1.2.1 Rooftop Unit 1--2......................................................................

1.2.2 Condensing Section 1--2...............................................................

1.2.3 Evaporator Section 1--4................................................................

1.2.4 Drivers Evaporator (Optional) 1--6.......................................................

1.2.5 Compressor Assembly 1--6.............................................................

1.2.6 System Operating Controls And Components 1--7.........................................

1.2.7 280P & 282P (PWM) Electronic Thermostat Controller 1--7.................................

1.2.8 CSDD BT--324 (Carrier--Sutrak Digital Display) Microprocessor 1--7..........................

1.2.9 Motor Fault Board (Optional) 1--7........................................................

1.3 REFRIGERATION SYSTEM COMPONENT SPECIFICATIONS 1--7.............................

1.4 ELECTRICAL SPECIFICATIONS -- MOTORS 1--7............................................

1.5 SAFETY DEVICES 1--8...................................................................

1.6 AIR CONDITIONING REFRIGERATION CYCLE 1--8..........................................

1.7 HEATING CYCLE 1--8....................................................................

OPERATION (Manual Controller) 2--1..............................................................

2.1 STARTING, STOPPING AND OPERATING INSTRUCTIONS 2--1..............................

2.1.1 Starting 2--1..........................................................................

2.1.2 Stopping 2--1.........................................................................

2.2 PRE--TRIP INSPECTION 2--1..............................................................

2.3 MODES OF OPERATION 2--2.............................................................

2.3.1 Temperature Control 2--2...............................................................

2.3.2 Cooling Mode 2--2.....................................................................

2.3.3 Heating Mode 2--2.....................................................................

2.3.4 Boost Pump (Optional) 2--2.............................................................

2.3.5 Vent Mode 2--2.......................................................................

2.3.6 Compressor Unloader Control (Only with 05G or 05K Compressors) 2--2.....................

2.3.7 Override Mode -- AC310 (Dehumidification) 2--2..........................................

2.3.8 Evaporator Fan Speed Selection 2--3....................................................

2.3.9 Compressor Clutch Control 2--3.........................................................

(A--6, TM--16, TM--21) 2--3....................................................................

2.4 SEQUENCE OF OPERATION (280P / 282P) 2--3.............................................

2.4.1 Electronic Thermostat 2--3.............................................................

OPERATION BT324 Controller 3--1.................................................................

3.1 STARTING, STOPPING AND OPERATING INSTRUCTIONS 3--1..............................

3.1.1 Starting

3.1.2 Stopping 3--1.........................................................................

3.2 PRE--TRIP INSPECTION 3--1.............................................................

3.3 SEQUENCE OF OPERATION BT324 CSDD 3--2.............................................

3.3.1 Function of Keys when “Engine On” and controller active: 3--2...............................

3.3.2 Illuminating Indications (Display) 3--2....................................................

3--1..........................................................................

i

T--30404/08

TABLE OF CONTENTS Continued:

3.4 Operating Instructions BT324 3--2...........................................................

3.4.1 Display 3--2..........................................................................

3.4.2 Interior Temperature Control 3--2........................................................

3.4.3 Ventilation 3--2........................................................................

3.4.4 Reheat (optional) 3--3..................................................................

3.4.5 Temperature Indication 3--3.............................................................

3.5 CHANGING BETWEEN 5F (FAHRENHEIT) AND 5C (CELCIUS ) 3--3..........................

TROUBLESHOOTING 4--1.........................................................................

4.1 System Will Not Cool 4--1..............................................................

4.2 System Runs But Has Insufficient Cooling 4--1............................................

4.3 Abnormal Pressures 4--1...............................................................

4.4 Abnormal Noise Or Vibrations 4--1.......................................................

4.5 No Evaporator Air Flow Or Restricted Air Flow 4--2........................................

4.6 Expansion Valve Malfunction 4--2........................................................

4.7 Heating Malfunction 4--2...............................................................

SERVICE 5--1....................................................................................

5.1 MAINTENANCE SCHEDULE 5--1...........................................................

5.2 REMOVING EVAPORATOR COVER 5--1....................................................

5.3 REMOVING CONDENSER COVER 5--1.....................................................

5.4 INSTALLING MANIFOLD GAUGE SET 5--1..................................................

5.4.1 Installing R--134a Manifold Gauge/Hose SET 5--1.........................................

5.5 PUMPING THE SYSTEM DOWN OR REMOVING THE REFRIGERANT CHARGE 5--2...........

5.5.1 System Pump Down For Low Side Repair 5--2............................................

5.5.2 Removing Entire System Charge 5--3....................................................

5.6 REFRIGERANT LEAK CHECK 5--3.........................................................

5.7 EVACUATION AND DEHYDRATION 5--3....................................................

5.7.1 General 5--3..........................................................................

5.7.2 Preparation 5--3.......................................................................

5.7.3 Procedure for Evacuation and Dehydrating System 5--3....................................

5.8 ADDING REFRIGERANT TO SYSTEM 5--3..................................................

5.8.1 Checking Refrigerant Charge 5--3.......................................................

5.8.2 Adding Full Charge 5--4................................................................

5.9 CHECKING FOR NONCONDENSIBLES 5--4................................................

5.10 CHECKING AND REPLACING HIGH OR LOWPRESSURE CUTOUT SWITCH 5--4..............

5.10.1 Replacing High Or Low Pressure Switches 5--4...........................................

5.10.2 Checking High Or Low Pressure Switches 5--4............................................

5.11 FILTER-DRIER 5--5.......................................................................

5.11.1 To Check Filter--Drier 5-- 5..............................................................

5.11.2 To Replace Filter--Drier Assembly 5--5...................................................

5.12 SERVICING THE HEAT VALVE 5--5........................................................

5.12.1 Coil Replacement 5--6.................................................................

5.12.2 Internal Part Replacement 5--6..........................................................

5.12.3 Replace Entire Valve 5--6

..............................................................

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ii

TABLE OF CONTENTS Continued:

5.13 SERVICING THE LIQUID LINE SOLENOID VALVE 5--6.......................................

5.13.1 Coil Replacement 5--6.................................................................

5.13.2 Internal Part Replacement 5--6..........................................................

5.13.3 Replace Entire Valve 5--6...............................................................

5.14 SERVICE VALVES 5--7....................................................................

5.15 REPLACING RETURN AIR FILTERS 5--7...................................................

5.16 THERMOSTATIC EXPANSION VALVE 5--8..................................................

5.16.1 Valve Replacement 5--8................................................................

5.16.2 Superheat Measurement 5--9...........................................................

ELECTRICAL 6--1................................................................................

6.1 INTRODUCTION 6--1.....................................................................

LIST OF FIGURES

Figure 1--1 AC310/350 Rooftop Units 1--2...........................................................

Figure 1--2 Condensing Section Components (AC310 -- Dual Loop -- GEN I) 1--3..........................

Figure 1--3 Condensing Section Components (AC350 Single Loop -- GEN II) 1--4.........................

Figure 1--4 Evaporator Section Components (AC310 --Dual Loop -- GEN I) 1--5...........................

Figure 1--5 Evaporator Section Components (AC350 Single Loop -- GEN II) 1--6..........................

Figure 1--6 Refrigerant Flow Diagram -- Cooling (Dual Loop) 1--9...........................................

Figure 1--7 Flow Diagram -- Heating 1--10...............................................................

Figure 1--8 Refrigerant Flow Diagram, Cooling (Single Loop) AC350 1--11.................................

Figure 1--9 Sheet 1 -- Electrical Control Board (280P) 1--12.............................................

Figure 1--9 Sheet 2 Legend 1--13....................................................................

Figure 1--10 AC350 With BT324 Control 1--14.........................................................

Figure 1--11 Motor Fault Board (Optional) 1--15........................................................

Figure 2.1 Control Switches (Typical) 2-- 1..............................................................

Figure 2.2 280P / 282P Thermostat 2-- 3.............................................................

Figure 3--1 Bus Dash With A/C Switch & BT324 CSDD Controller 3--1...................................

Figure 3--2 BT324 CSDD Controller 3--2.............................................................

Figure 5--1 Manifold Gauge Set (R--134a) 5--2........................................................

Figure 5--2 In--Line Service Connections 5--3.........................................................

Figure 5--3 Checking High Pressure Switch 5--4......................................................

Figure 5--4 Filter--Drier Removal 5--5................................................................

Figure 5--5 Heat Valve 5--6........................................................................

Figure 5--6 Liquid Line Solenoid Valve 5--7...........................................................

Figure 5--7 Service Valve R134a (High Side) 5--7.....................................................

Figure 5--8 Return Air Grill Assembly With Air Filter Showing 5--7.......................................

Figure 5--9 Diffuser and Filter Element 5--8..........................................................

Figure 5--10 Filter, Diffuser and Composit Frame 5--8.................................................

Figure 5--11 Return Air Grill Assembly With Diffuser And Composit Frame Showing 5--8...................

Figure 5--12 Thermostatic Expansion Valve 5--8......................................................

Figure 5--13 Thermostatic Expansion Valve Bulb and Thermocouple 5--9.................................

Figure 6--1 System Controls (Typical) 6--2...........................................................

Figure 6--2 Manual Controls With Manual Reheat Control (Sheet 1) 6--3.................................

Figure 6--3 Manual Controls With Manual Reheat Control (Sheet 2) 6--4.................................

iii

T--30404/08

LIST OF FIGURES Continued:

Figure 6--4 Evaporator Motors 1 -- 4 6-- 5.............................................................

Figure 6--5 Evaporator Motors 5 -- 8 6-- 6.............................................................

Figure 6--6 Condenser Motors 6--7..................................................................

Figure 6--7 BT324 Controls With (1) Compressor (AC350) 6--8.........................................

Figure 6--8 BT324 Control Circuit (AC350) 6--9.......................................................

Figure 6--9 BT324 Evaporator Motors (AC350) 6--10...................................................

Figure 6--10 CSDD BT324 Condenser Motors 6--11....................................................

Figure 6--11 AC350 With BT324 Control 6--12.........................................................

Figure 6--12 CSDD BT324 Control Circuit 6--13........................................................

Figure 6--13 CSDD BT324 6--14.....................................................................

Figure 6--14 Thermostat (One/Two Compressors) 6--15................................................

Figure 6--15 Thermostat (One/Two Compressors) 6--16................................................

Figure 6--16 Thermostat (One/Two Compressors) 6--17................................................

Figure 6--17 Thermostat (One/Two Compressors) 6--18................................................

Figure 6--18 Thermostat (One/Two Compressors) 6--19................................................

LIST OF TABLES

Table 1--1 AC310 Models 1--1.......................................................................

Table 1--2 AC 350 Models 1--1......................................................................

Table 1--3 Additional Support Manuals 1--1............................................................

Table 2--1 Unloader UV1 Relay 2--2..................................................................

Table 2--2 Unloader UV2 Relay 2--2..................................................................

Table 4--1 General System Troubleshooting Procedures 4--1............................................

Table 5--1 R-134a Temperature - Pressure Chart 5--10..................................................

T--304 04/08

iv

SAFETY SUMMARY

GENERAL SAFETY NOTICES

The following general safety notices supplement the specific warnings and cautions appearing elsewhere in this
manual. Theyarerecommended precautionsthatmust beunderstoodand appliedduring operationandmaintenance
of the equipment covered herein. A listing of the specific warnings and cautions appearing elsewhereinthe manual
follows the general safety notices.

FIRST AID

An injury, nomatter how slight, should never gounattended. Always obtain first aid or medical attention immediately.

OPERATING PRECAUTIONS

Always wear safety glasses.
Keep hands, clothing and tools clear of the evaporator and condenser fans.
Noworkshould beperformedon theunituntilall start-stop switches areplacedin the OFF position, andpowersupply

is disconnected.
Always work in pairs. Never work on the equipment alone.
In case of severe vibration or unusual noise, stop the unit and investigate.

MAINTENANCE PRECAUTIONS

Beware of unannounced starting of the evaporator and condenser fans. Do not open the unit cover before turning
power off.

Be sure power is turned off before workingonmotors, controllers, solenoidvalvesandelectrical controls. Tagcircuit
breaker and power supply to prevent accidental energizing of circuit.

Donot bypassany electricalsafetydevices,e.g. bridginganoverload,or usinganysortof jumperwires. Problemswith
the system should be diagnosed, and any necessary repairs performed by qualified service personnel.

When performing any arcweldingon the unit, disconnect all wire harness connectors from the modulesinthecontrol
box. Donotremovewireharness fromthemodules unless you are grounded to the unit frame with a static-safewrist
strap.

In case of electrical fire, open circuit switch and extinguish with CO

(never use water).

2

04/08

Safety--1

T--304

SPECIFIC WARNINGS AND CAUTIONS

WARNING

Be sure to observe warnings listed in the safety summary in the front of this manual before per-

forming maintenance on the hvac system

WARNING

Read the entire procedure before beginning work. Park the vehicle on a level surface, with park-

ing brake applied. Turn main electrical disconnect switch to the off position.

WARNING

Do Not Use A Nitrogen Cylinder Without A Pressure Regulator

WARNING

Do Not Use Oxygen In Or Near A Refrigeration System As An Explosion May Occur.

WARNING

The Filter-drier May Contain Liquid Refrigerant. Slowly Loosen The Connecting Nuts And Avoid

Contact With Exposed Skin Or Eyes.

CAUTION

The AC310 & AC350 Rooftop Systems have R134a service port couplings installedon the compres­sor and 1/4 inch flare (Acme) fittings installed on the unit piping.

CAUTION

To prevent trapping liquid refrigerant in the manifold gauge set be sure set is brought to suction

pressure before disconnecting.

T--304 04/08

Safety--2

SECTION 1

DESCRIPTION

1.1 INTRODUCTION

This manual contains Operating Instructions, Service
Instructions and Electrical Data for the Model AC310
and AC350 Air Conditioning and Heating equipment
furnished by Carrier Transport Air Conditioning as
shown in Table 1--1 and Table 1--2.

Model AC310/350 systems consists of a Rooftop unit
containing the condensing section, the evaporator
section and engine compartment mounted
compressor(s). To complete the system, the air

Table 1-- 1 AC310 Models

Model AC310

77--62031--00 12 VDC Manual (280P) Yes X X
77--62031--01 24 VDC Manual (280P) Yes X X
77--62031--02 12 VDC BT324 Yes X X
77--62031--03 24 VDC BT324 Yes X X

77--62032--00 12 VDC
77--62032--01 24 VDC Manual (280P) Yes X X

77--62032--02 -- -- -- -- -- -­77--62032--03 12 VDC Manual (280P) Yes X X
77--62032--04 12 VDC Manual (280P) Yes X X
77--62032--05 12 VDC BT324 Yes X X

*77--62032--06 12 VDC BT324 (Tropic) Yes X X

Voltage Controller With Heat Dual Loop Single Loop W/Covers

Sytronic System

& Manual (280P)

conditioning and heating equipment interfaces with an
optional drivers evaporator (dash--air), electrical
cabling, refrigerant piping, engine coolant piping (for
heating), duct work and other components furnished by
Carrier Transport Air Conditioning and/or the bus
manufacturer.

Additional support manuals are shown in Table 1--3.
Operation of the unit is controlled automatically by an

electronic thermostat. The controlls maintain the
vehicle’s interior temperature at the desired set point.

Yes X X

*NOTE: 77--62032--06 (Tropic) -- Has an AC310 Evaporator Section & an AC350 Condenser Section.

Table 1-- 2 AC 350 Models

Part Number

77--62041--00 24 VDC -- -- -- X -­77--62041--01 24 VDC Manual Yes -- Yes
77--62041--02 24 VDC Manual Yes X No
77--62041--03 24 VDC -- -- -- -- -­77--62041--04 24 VDC BT324 No X No
77--62041--05 24 VDC BT324 No X Yes
77--62041--06 24 VDC BT324 Yes X Yes
77--62041--07 24 VDC BT324 Yes X No
77--62041--10 24 VDC BT324 Yes X Yes

MANUAL NUMBER

T--304PL AC--310/350 Service Parts List

T--200PL 05G Compressor Service Parts List
62--02756 05G Compressor Operation & Service
62--11052 05G Compressor -- Twin Port Workshop Manual
62--11053 05G Compressor -- Twin Port Service Parts List
62--02460 05K Compressor Service Parts List
62--02491 05K Compressor Operation & Service

Voltage Controller With Heat Dual Loop Single Loop W/Covers

Table 1-- 3 Additional Support Manuals

EQUIPMENT COVERED TYPE OF MANUAL

04/08

1--1

T--304

1.2 GENERAL DESCRIPTION

1.2.1 Rooftop Unit

The rooftop unit includes the condenser section and the evaporator section (See Figure 1--1).

Evaporator Section

Condenser Section

AC310

AC350

Figure 1--1 AC310/350 Rooftop Units

1.2.2 Condensing Section

The dual (See Figure 1--2) and single loop (See
Figure 1--3)condensing sections includethecondenser
coils, four (4) or six (6) fan and motor assemblies,
filter-driers, receivers, and filter drier service valves.

The condenser coils provide heat transfer surface for
condensing refrigerant gas at a high temperature and
pressure into aliquidat high temperatureand pressure.
The condenser fans circulate ambient air across the
outside of the condenser tubes at a temperature lower

Evaporator Section

Condenser Section

than refrigerant circulating inside thetubes; this results
in condensation of the refrigerant into a liquid. The
filter-drier removes moisture and debris from the liquid
refrigerant before it enters the thermostatic expansion
valve in the evaporator assembly. The service valves
enable isolation of the filter-drier for service.

The receiver collects and stores liquid refrigerant. The
receiver is also fitted with a pressure relief valve which
protects the system from unsafe high pressure
conditions.

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1--2

04/08

9

9

9

8

7

2

1

1

2

3

4

1. Condenser Coil Assembly

2. Receiver

3. Service Valve (High Side)

4. Filter Drier Upper Support

5. Filter Drier

Figure 1--2 Condensing Section Components (AC310 -- Dual Loop -- GEN I)

5

3

AC310

5

4

3

Dual Loop

6

6. Filter Drier Lower Support

7. Condenser Fan and Motor Assembly

8. Condenser Motor Support

9. Discharge Line Check Valve (Location)

04/08

1--3

T--304

5

1

44

1

1 Condenser Coil Assembly

Receiver Tank (Part Of Coil Assembly)

2 Service Valve

Figure 1--3 Condensing Section Components (AC350 Single Loop -- GEN II)

1.2.3 Evaporator Section

The dual loop AC310 & AC350 (GEN I) evaporator
section (SeeFigure 1--4) includes the evaporator coils,
eight (8) or twelve (12) single--shafted blower/motor
assemblies, two heater coil assemblies, two
thermostatic expansion valves, two liquid line solenoid
valves, and condensate drain connections.

NOTE

The GEN I seriesof AC310 & AC350 evapora­tors are suppliedwithsingle shaft blower/motor
assemblies. The GEN II series have dual shaft
blower/motor assemblies.

The single loop AC310 & AC350 evaporator section
(See Figure 1--5)includes the evaporator coils, four (4)
or six (6) double--shafted blower/motor assemblies,
heater coil assemblies, one thermostatic expansion

4

2

3

2

5

3 Filter Drier
4 Fan & Motor
5 Frame (Aluminum)

valve, one liquid line solenoid valve (to add in--dash
service port), and condensate drain connections.

The liquidlinesolenoid valve closes whenthe system is
shut down to prevent flooding of coils and the
compressor with liquid refrigerant. The evaporatorcoils
provide heat transfer surface for transferring heat from
air circulating over the outside of the coil to refrigerant
circulating inside the tubes;thus providing cooling. The
heating coils provide a heat transfer surface for
transferring heat from engine coolant water circulating
inside the tubes to air circulating over the outside
surface of the tubes, thus providing heating. The fans
circulate the air overthecoils.Theairfilters remove dirt
particles from theair before itpassesover thecoils.The
thermostatic expansion valve meters the flow of
refrigerant entering theevaporatorcoils.Theheat valve
controls the flow of engine coolant to the heating coils
upon receipt of a signal from the controller. The
condensate drain connections provide a means for
connecting tubingfordisposing ofcondensatecollected
on the evaporator coils during cooling operation.

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1--4

04/08

3

7

4

9

6

8

2

1

Return Air

Section

AC310

Dual Loop

6

4

5

1. Evaporator Coil Assembly

2. Heater Coil

3. Expansion Valve

4. Evaporator Blower Assembly

5. Evaporator Motor

Figure 1--4 Evaporator Section Components (AC310 -- Dual Loop -- GEN I)

6. Sight Glass

7. Heating Line

8. Access Port

9. Liquid Line Solenoid

04/08

1--5

T--304

6

2

4

1

5

4

1. Evaporator Coil Assembly

2. Heater Coil

3. Expansion Valve

4. Evaporator Blower/Motor Assembly

Figure 1--5 Evaporator Section Components (AC350 Single Loop -- GEN II)

8

3

6

7

1

2

5. Control Panel

6. Heater Line

7. Front Evaporator Port

8. Liquid Line Solenoid

1.2.4 Drivers Evaporator (Optional)

Thedriversevaporatorassemblyis normally installedin
thevehicledashareaandinterfaceswiththerooftopunit
electrical cabeling and refrigerant piping.

The drivers evaporator assembly includes an
evaporator coil, thermalexpansion valve, blower motor
assembly and a condensate drain connection. Refer to
the OEM technical literature for driver’s evaporator
information.

1.2.5 Compressor Assembly
a. Dual Loop Compressors A--6 & TM--21

The standard AC310 dual loop compressor assembly
includes the refrigerant compressor, clutch assembly,
in--line high & low pressure switches, suction
accumulator and in--line suction and discharge
servicing (charging) ports.

b. Single Loop Compressor TM--31

The TM--31 compressor assembly used only with the
AC310 Single Loop Unit includes the refrigerant
compressor, clutch assembly, suction & discharge
service valves, high pressure switch, low pressure
switch, suction accumulator and suction anddischarge
servicing (charging) ports.

T--304

c. Single Loop Compressors 05G & 05K

The 05G (AC350) & 05K (AC310) compressor
assemblies used withthesingleloopunits,includesthe
clutch assembly, suction & discharge service valves,
high pressure switch, low pressure switch, suction and
discharge servicing (charging) ports and electric
solenoid unloaders.

Thecompressorraisesthepressureand temperatureof
the refrigerant and forces it into the condenser coil
tubes. Theclutchassemblyprovidesa means ofdriving
the compressors by the vehicle engine. Suction and
discharge servicing (charging) ports mounted on the
compressor fittings enable connection of charging
hoses for servicing of the compressor, as well as other
parts of the refrigerant circuit.Thehighpressureswitch
contacts open on a pressure rise to shut down the
system when abnormally high refrigerant pressures
occur.

The electric unloaders (05G & 05K) provide a means of
controlling compressor capacity, which enables control
of temperature inside the vehicle. The suction and
discharge service valves enable servicing of these
compressors.

1--6

04/08

1.2.6 System Operating Controls And Compo­nents

Thesystem isoperated byanelectronicthermostattype
controller and/or manually operated switches. The
manually operated switches are located on the drivers
control and may consist of a single ON/OFF switch or
additional switches. The controller regulates the
operational cycles of the system by energizing or
de--energizing relays on the relay board in response to
deviations in interior temperature. Modes of operation
includeCoolingandHeating.Onsystemsfittedwithonly
an ON/OFF switch, the controller will cycle the system
between the operating modes as required to maintain
desired set point temperature (See Section 6 for wiring
diagrams).

In the heat mode the heat valves are opened to allow a
flow of engine coolant through the heat coils located in
the evaporator section. The evaporatorfans operate to
circulate air over the heat coils in the same manner as
the cooling mode.

In the cooling mode the compressor is energized while
the evaporator and condenser fans are operated to
provide refrigeration as required. The compressor (s)
capacity is matched to the bus requirements. Once
interior temperature reaches the desired set point, the
compressor(s) is deenergized.

1.2.7 280P & 282P (PWM) Electronic Thermostat
Controller

This typecontrollerhas three (3)modes,Cool, Ventand
Heat.

The range on the potentiometer is 62.6° -- 8 6° F
(17--30° C).

1.2.8 CSDD BT--324

(Carrier--Sutrak Digital Display)

Microprocessor

This Carrier Sutrak Digital Display (BT--324) controller
has three (3)modes,Auto, V ent(Cycleclutchtype)and
Heat.

1.2.9 Motor Fault Board (Optional)

The motor fault board(SeeFigure 1--11)consists ofred
and green LED’s, which when illuminated, will reflect
each motors state of condition. When the evaporator
and condenser motors are energized, the green LED’ s
will beilluminated.Ifared LED is energized, it willshow
an “open circuit” condition, indicative of a motor failure.
The green LED will not be illuminated at this time. The
motor fault board is a seperate circuit board that is
located at the return air section. The return air grill is
oppened to view the LED indicators.

1.3 REFRIGERATION SYSTEM COMPONENT

SPECIFICATIONS

a. Refrigerant Charge R--134a (Approximate)

NOTE

Refrigerant charge will dependon hose lengths
and diameters; or if there is an In--Dash unit
(front evaporator). The followingshouldonly be
used as a guideline.

AC310 Dual Loop A--6 or TM--21 Compressor

6 Pounds (2.7 kg) -- Curbside
8 Pounds (3.6 kg) -- Roadside

AC310 -- Single Loop TM--31 Compressor

12 Pounds (5.4 kg) without In--Dash unit

AC310 -- Single Loop 05G or 05K Compressor

13.2 to 15.4 Pounds (6.0 to 7.0 kg) without
In--Dash unit

AC350 -- Single Loop 05G or 05K Compressor

16.5 to 18.7 Pounds (7.5 to 8.5 kg) without
In--Dash unit

For systems with In--Dash unit (Optional)

Add 2 pounds (0.9 kg) to above listed charge.

b. Compressors

Compressor

Weight, (Dry) 34.5 Lbs.
Oil Charge 10 Oz. PAG (07--00333--00)

Compressor TM--21

Weight, (Dry) 7.5 Lbs. (3.4 kg)
Oil Charge

Compressor TM--31

Weight, (Dry) 21 Lbs.
Oil Charge

Compressor Carrier 05K

Weight, (Dry) 108 Lbs.
Oil Charge

Compressor Carrier 05G

Weight, (Dry) 146 Lbs. W/Clutch
Oil Charge

c. Thermostatic Expansion Valve:

Superheat Setting (Externally Adjustable) Factory
Setat9to18°F(±4°F) MOP Setting: 55 ±4 psig
(3.74 ±2.27 bar)

d. High Pressure Switch (HPS) Normally Closed

Opens at: 360 ±10 psig (20.41 ±0.68bar)
Closes at: 280 ±10 psig (13.61 ±0.68bar)

e. Low Pressure Switch (LPS) Normally Open

Opens at: 6 ±3psig (0.41 ±0.20 bar)
Closes at: 25 ±3psig(1.7±0.20 bar)

f. Water Temperature Switch (WTS)

[Bus Manufacturer Supplied -- Suggested close on
temperature rise at 105°F(41°C)]

1.4 ELECTRICAL SPECIFICA TIONS -- MOTORS
a. Evaporator Blower/Motor

Evaporator Motor

Horsepower (kW) 1/8 (.09)
Full Load Amps (FLA) 9.5 19
Operating Speed High/

Low (RPM)
Bearing Lubrication

A6 (No longer Available)

6.1 Oz. (180 cc) PAG
(46--50006--00)

16.9 Oz. (500cc) PAG
(46--50006--00)

5.5 Pints POE

(07--00317--00pk6)

7.75 Pints POE

(07--00317--00pk6)

Permanent Magnet

24 VDC 12 VDC

4200
1850

Factory Lubricated

(additional grease not required)

Change 07/09

1--7

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b. Condenser Fan Motor

Condenser Motor

Permanent Magnet

24 VDC 12 VDC

Horsepower (kW) 1/8 (.09)
Full Load Amps (FLA) 9 18
Operating Speed

(RPM)
Bearing Lubrication

(additional grease not required)

2950

Factory Lubricated

c. Temperature Sensors (Return Air Sensor)

Input Range: --52.6 to 158° F (--47 to 70°C)
Output: NTC 10K ohms at 77° F(25°C)

d. Ambient Sensor (Optional)

Opens at: 25° F(10°C)
Closes at: 35° F(1.7°C)

1.5 SAFETY DEVICES

System components are protected from damage
caused by unsafe operating conditions with safety
devices. Safety devices with Carrier Transport Air
Conditioning supplied equipment include high pressure
switch (HPS), low pressure switch (LPS), circuit
breakers and fuses.

a. Pressure Switches

High Pressure Switch (HPS)

During the air conditioning cycle, compressor clutch
operation will automatically stop if the HPS switch
contacts open due to an unsafe operating condition.
Opening HPS contacts de-energizes the compressor
clutchshuttingdownthecompressor.Thehighpressure
switch (HPS) is installed at the compressor assembly
(05G, 05K & TM--31).

Low Pressure Switch (LPS)

The low pressure switch is installed close to the
compressor andopenson apressuredrop to shutdown
the system when a low pressure condition occurs. The
lowpressureswitchisinstalledat thecompressor(05G,
05K & TM--31).

NOTE

Ondualloop systemsthatuse theA--6, TM--21
& some TM31’s,the pressure switches are not
located onthe compressors. They are installed
in--line.

b. Fuses and Circuit Breakers

TheRelayBoard is protected against highcurrentbyan
OEM supplied circuit breaker or fuse located in thebus
battery compartment (150 Amp for 12 VDC & 125 Amp
for 24 VDC systems). Independent 15 Amp, 24 VDC or
20 Amp, 12 VDC fuses protect each motor while the
output circuits are protected by an additional 5 Amp
circuit breaker. Duringahigh current condition, the fuse
may open.

1.6 AIR CONDITIONING REFRIGERATION
CYCLE

When air conditioning (cooling) is selected by the
controller, the unit operates as a vapor compression
system using R-134a as a refrigerant (See Figure 1--6
Dual Loop & Figure 1--8 Single Loop flow diagrams).
The main components of the system are the A/C
compressor, air-cooled condenser coils, receiver,
filter-drier, thermostatic expansion valve, liquid line
solenoid valve and evaporator coils.

The compressor raises the pressure and the
temperature of the refrigerant and forces it into the
condenser tubes. The condenser fan circulates
surroundingair(whichisatatemperature lowerthanthe
refrigerant) over the outside of the condenser tubes.
Heat transfer is established from the refrigerant(inside
the tubes) to thecondenserair(flowingoverthetubes).
The condensertubeshavefins designed toimprovethe
transfer of heat from the refrigerant gas to the air; this
removal of heat causes the refrigerant to liquefy, thus
liquid refrigerant leaves the condenser and flows to the
receiver.

The refrigerant leavesthereceiver and passes through
the receiver outlet/service valve, through a filter-drier
where a descecant keeps the refrigerant clean and dry.

From the filter-drier, the liquid refrigerant then flows
through the liquid line solenoid valve to the sight--glass
and then to the thermostatic expansion valve. The
thermal expansion valve reduce pressure and
temperature of the liquid and meters the flow of liquid
refrigerant to the evaporator to obtain maximum use of
the evaporator heat transfer surface.

The low pressure, low temperatureliquidthat flows into
the evaporator tubes is colder than the air that is
circulated over the evaporator tubes by the evaporator
fans (fans). Heat transfer is established from the
evaporator air (flowing over the tubes) to the refrigerant
(flowing inside the tubes). The evaporator tubes have
aluminum fins to increase heat transfer from the air to
the refrigerant; therefore the cooler air is circulated to
the interior of the bus. Liquid line solenoid valve closes
during shutdown to prevent refrigerant flow.

The transfer of heat from the air to the lowtemperature
liquid refrigerant in the evaporator causes the liquid to
vaporize. This low temperature, low pressure vapor
passes through the suction line and returns to the
compressor where the cycle repeats.

1.7 HEATING CYCLE

Heating circuit (See Figure 1--7) components furnished
byCarrier Transport AirConditioninginclude theheater
cores and solenoidoperated heat valves. Components
furnished by the bus manufacturer may include awater
temperature switch (WTS) and boost water pump.

The controller automatically controls the heat valves
during the heating mode to maintain required
temperatures inside the bus. Engine coolant (glycol
solution) is circulated through the heating circuit by the
engine and an auxiliary boost water pump. When the
heat valvesolenoidsareenergized, the valves willopen
to allow engine coolant to flow throughthe heater coils.
The valves are normally closed so that if a failure
occurs, the system will be able to cool.

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1--8

04/08

5

3

6

2

4

1

4

1

3

1 Thermal Expansion Valve
2 Liquid Line Sight Glass
3 Service Port
4 Liquid Line Solenoid
5 Evaporator Coil
6 Heat Coil

Note: Items 1 through 12 are typical, both systems.

Driver’ s
Evaporator

12

7

9

9

11

10

8

7 Subcooler
8 Compressor (TM--21 or A--6)

9 Service Valve
10 Condenser Coil
1 1 Filter--Drier
12 Receiver

Figure 1--6 Refrigerant Flow Diagram -- Cooling (Dual Loop)

04/08

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1

1

4

*

SUPPLY
RETURN

4

*

1. Heat Coil

2. Vehicle Radiator

3. Boost Pump

3

2

4. Heat Solenoid Valve

* Optional Hand V alve

Figure 1--7 Flow Diagram -- Heating

NOTE: Inordertoensurewaterisenteringtheheater coils sufficientlyheated, it issuggestedthat

theOEMsupplied WaterTemperatureSwitch(WTS)closeontemperature riseat150°F( 65.5°C).

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1--10

04/08

Discharge
Liquid
Suction
Coolant

11

Relief Valve

Dash Air
Suction Line

8

10

4

Discharge Check Valve

5

Dash Air
Liquid Line

4

9

9

CONDENSER

8

EVAPORATOR

3

3

7

Figure 1--8 Refrigerant Flow Diagram, Cooling (Single Loop) AC350

1. Thermal Expansion Valve

2. Liquid Line Sight Glass

3. Service Port R134a
4 Service Port 1/4 Flare (Acme)

5. Liquid Line Solenoid

6. Evaporator Coil

1

2

5

4

6

6

7. Compressor

8. Service Valve

9. Condenser Coil

10. Filter--Drier

1 1. Receiver

04/08

1--11

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