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

T--304

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.

T--304

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

1--9

T--304

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).

T--304

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

T--304

Ref. Sutrac 60--01--21--062

28

30

32

34

36

38

40

42

44

46

29

31

33

35

37
39

41
43

45

23

24

F1A

F2A

F3A
F4A
frei
F1M
F2M
F3M
F4M
F5M
F6M
F7M
F8M
F13M
F14M
F15M

F16M

frei
frei

frei

K1A

K2A

K1M

K5M K4M K3M K2M

8

9

10

11

12

1314151617

25

26 27

22

K3A

K4A

K13M

6

A1P

5

4

3

V5
V4
V3

V2
V1

B1N

7

K9M K8M K7M K6M

K11M K10M

K12M

K14M

K15M

18

19

20

21

2

1

47

CLR1

CLR2

48

SeeFigure1--9Sheet2Legend

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

T--304

1--12

Ref. Sutrak Schematic 65--01--28--056--01--3

04/08

LEGEND

1 V1, Diode, Dash Switch
2 V2, Diode, Dash Switch
3 V3, Diode, Dash Switch
4 V4, Diode, Thermostat, Cooling
5 V5, Diode, Thermostat, Heating
6 Thermostat
7 Return Air Sensor
8 K1M, Relay, Evaporator Low Speed

9 K2M, Relay, Evaporator High Speed
10 K3M, Relay, Evaporator High speed
1 1 K4M, Relay, Evaporator Low Speed
12 K5M, Relay, Evaporator High Speed
13 K6M, Relay, Evaporator High Speed
14 K7M, Relay, Evaporator Low Speed
15 K8M, Relay, Evaporator High speed
16 K9M, Relay, Evaporator High Speed
17 K10M, Relay, Evaporator Low Speed
18 K11M, Relay, Evaporator High Speed
19 K12M, Relay, Evaporator High Speed
20 K14M, Relay, Evaporator Main, High speed
21 K15M, Relay, Condenser Motors
22 K13M, Relay, Condenser Motors
23 K1A, Relay, Alternator Power
24 K2A, Relay, Compressor Clutch
25 K3A, Relay, Heat Valve and Water Pump
26 K4A, Relay, Evaporator Speed
27 F1A, Fuse, Alternator Output
28 F2A, Fuse, Heat Valve and Water Pump
29 F3A, Fuse, Compressor Clutch
30 F4A, Fuse, Compressor Clutch
31 SPARE

32 F1M, Fuse, Evaporator Motor
33 F2M, Fuse, Evaporator Motor
34 F3M, Fuse, Evaporator Motor
35 F4M, Fuse, Evaporator Motor
36 F5M, Fuse, Evaporator Motor
37 F6M, Fuse, Evaporator Motor
38 F7M, Fuse, Evaporator Motor
39 F8M, Fuse, Evaporator Motor
40 F13M, Fuse, Evaporator Motor
41 F14M, Fuse, Evaporator Motor
42 F15M, Fuse, Condenser Motor
43 F16M, Fuse, Condenser Motor
44 SPARE
45 SPARE
46 SPARE
47 CLR1, Clutch Lockout Relay #1
48 CLR2, Clutch Lockout Relay #2
Ambient Sensor -- (Condenser)
Humidity Control Sensor -- (Return Air)
OEM Installed Controls
CR1 & CR2, Clutch Relays

04/08

See Figure 1--9 Sheet 1 -- Electrical Control Board

Figure 1--9 Sheet 2 Legend

1--13

T--304

1....K1A = Compressor Clutch -- LiquidLine Solenoid -- Condenser Fans

2....K2A = Heat Valve -- Boost Pump

3....K3A = Evaporator Fans

4....K1M -- K6M = Individual Evaporator Fans (M1M -- M6M)

5....K7M -- K9M = Individual Condenser Fans (M21M -- M26M)

6....Fuse = Boost Pump & Heat Valve

7....F13M -- F18M = Individual Condenser Fans

8....F1M -- F12M = Individual Evaporator Fans

9....U Reg = Evaporator Speed Regulation

10...X1 = Condenser Fans

11...X2 = Evaporator Fans

12...X3 -- X4 (Not Shown On Drawing) = Dash To Unit Interface Plug

+

K1M

K1A

K2A

K3A

+

GND

Relay Board

K2M

K3M

F1M 10A

F2M 10A

F3M 10A

K4M

K5M

F4M 10A

F5M 10A

F6M 10A

F7M 10A

F8M 10A

F9M 10A

F10M 10A

K6M

F11M 10A

F12M 10A

K7M

F13M 15A

X2

K8M

K9M

F14M 15A

F15M 15A

F16M 15A

F17M 15A

F18M 15A

K7M -- K9M

26.38.08.001

Ureg

Part Number

X1

--

Contact arrangement

Connect X1 -- X2

Figure 1--10 AC350 With BT324 Control

T--304

U3

U3A

+

Top View

SUTRAK SCHMATIC #65, 01, 28, 056--01--3

1--14

RELAYS FOR EVAP.MOTORS RELAYS FOR COND. MOTORS

UNIT

K1m -- K4M K7M -- K8M

AC310

K1M -- K6M

AC350

04/08

R26 R25

D14

D26

Q2

Q1

U1

Q3

Q4

D15

R27

R30

D18

D30

Q6

Q5

U2

Q7

Q8

D31

D19

R31

D22

D34

Q10

Q9

U3

Q11

Q12

D35

D23

R35

D13

D25

D28D27

D16

R28

R29

D17

D29

D32

D20

R32

R33R34

D21

D33

D36

D24

R36

R37

R38

C1

R40

R41

R42

C2

R43

R44

R45

R46

C3

R47

R48 R72

R61

R62

C13

C12

C14

C15

R63R39

R64

R65

R66

C9

C8

C10

C11

R67

R68

R69

R70

C13

C12

C14

C15

R71

R73

R74

U4

R75

R76

R77

R78

U5

R79

R80

R81

R82

U6

R83

R84

OPENCIRCUIT

DS13

DS14

C16

C17

C18

DS15

DS16

DS17

DS18

DS19

DS20

DS21

DS22

DS23

DS24

R12

D12

R24

MOTORPOWER

DS1

EVAP1

DS2

EVAP2

DS3

EVAP3

DS4

EVAP4

DS5

EVAP5

DS6

EVAP6

DS7

EVAP7

DS8

EVAP8

DS9

COND1

DS10

COND2

DS11

COND3

DS12

COND4

R11

D11

R23

D10

R22

POWER10--30V

POWER

OK

DS25

T25

T26

GROUND

R90

D51

D52

C23

C22

+ +

U8

R9

R8

R10

D9

D8

R21

R20

R19

D7

R7D6R6

R18

R85

R91

F1

D49

D50

R87

R86

C19

C20

R88

C21

R89

U7

R5

R4

R3

R2

D5

D4

R17

D3

R16

R14

R15

R1

D2

D1

R13

CARRIER CRO MOTOR FAULT BOARD

D37

T13

R49

D38

R50

D39

R51

D40

R52

D41

R53

D42

R54

D43

R55

D44

R56

D45

R57

D46

12- -00524--00

R58

D47

R59

D48

R60

MOTOR

T14

MOTOR

T15

MOTOR

T16

MOTOR

T17

MOTOR

T18

MOTOR

T19

MOTOR

T20

MOTOR

T21

MOTOR

T22

MOTOR

T23

MOTOR

T24

MOTOR

RS1

EVAP1

WHT/RED

BREAKER

RS2

EVAP2

BLK/RED

BREAKER

RS3

EVAP3

WHT/YEL

BREAKER

RS4

EVAP4

BLK/YEL

BREAKER

RS5

EVAP5

WHT/ORN

BREAKER

RS6

EVAP6

BLK/ORN

BREAKER

RS7

EVAP7

WHT/GRN

BREAKER

RS8

EVAP8

BLK/GRN

BREAKER

RS9

COND1

GRN/ORN

BREAKER

RS10

COND2

GRN/WHT

BREAKER

RS11

COND3

GRN/BLU

BREAKER

RS12

COND4

BREAKERGRN/YEL

X1--1

T1

X1--2

T2

X1--3

T3

X1--4

T4

X1--5

T5

X1--6

T6

X1--7

T7

X1--8

T8

X3--1

T9

X3--2

T10

X3--3

T11

X3--4

T12

04/08

Figure 1--11 Motor Fault Board (Optional)

1--15

T--304

SECTION 2

OPERATION (MANUAL CONTROLLER)

2.1 STARTING, STOPPING AND OPERATING
INSTRUCTIONS

The control switches supplied by Carrier Transport Air
Conditioning will be marked with international symbols
(See Figure 2.1).

Before starting, electrical power must be availablefrom
the bus power supply.

150Amp @12VDC or125Amp @24VDCfroma fusein
the battery compartment supplies power for the clutch,
evaporator and condenser assemblies.

LOW------HIGH

2.1.1 Starting

a. If the engine is not running, start the engine.
b. Actual start sequence depends on the operating co-

trol supplied. If only an ON/OFF switch is supplied,
place the switch in the ON (fan symbol) position to
start the system in the automatic mode.

c. After the pre--trip inspection is completed, the

switches may be set in accordance with the desired
control modes.

d. If low or high speed evaporator fan speed is desired,

press the FAN SPEED (fan symbol) button to bring
speed to the desired level.

2.1.2 Stopping

Placing the ON/OFF (Snowflake) switch in the OFF
position will stop the system operation by removing
power to the Logic Board.

OFF

Figure 2.1 Control Switches (Typical)

2.2 PRE--TRIP INSPECTION

After startingsystem,allow systemtostabilizefor tento
fifteen minutes and check for the following:

ON

HEATCOOL

Temperature Control

a. Listen for abnormal noises in compressoror fan mo-

tors.
b. Check compressor oil level (05G Compressor only).
c. Check refrigerant charge. (Refer to section 5.8.1 )

2--1

T--30404/08

2.3 MODES OF OPERATION

2.3.1 Temperature Control

Temperature is controlled by maintaining the return air
temperature measured at the return air grille. To
maintain cooling, turn the temperature control knob
towards the minus (--) symbol. To start heating cycle,
turn the temperature control knob towards the plus (+)
symbol (See Figure 2.1).

2.3.2 Cooling Mode

Cooling isaccomplished byenergizingthecompressor
and condenser fans, opening the liquid line solenoid
valve and closing the heating valve. Once interior
temperature reaches the desired set point, the system
will de--energize the compressor clutch and allow the
system to operate in the vent mode until further cooling
isrequired.Thetemperaturewillbemaintained within2°
C. or 3.6° F.

A controller programed for reheat will mantain
compressor operation and cycle the heat valve to allow
reheating of the return air. In the reheat mode interior
temperature is maintained at the desiredset pointwhile
additional dehumidification takes place.

2.3.3 Heating Mode

In the heat mode the liquid line solenoid is closed and
thecompressorand condenserfansare shutdown.The
heat valve is opened to allow a flow of engine coolant
through the heat section of the evaporator coil. The
evaporator fans speed is variedasrequiredto circulate
air over the evaporator coil based on the temperature
difference from setpoint.

Operating intheheating modeiscontrolled by thewater
temperature switch (WTS). The WTS is located on the
engine blockofthevehicleand is provided bytheOEM.
It senses the engine collant temperature and reverses
its contacts on temperature rise at 105° F. The switch
prevents the circulation of cooler air throughout the
vehicle as the engine comes up to temperature.

2.3.4 Boost Pump (Optional)

Whentheunit is inthe heatmode,andifa boostpumpis
supplied by the coach manufacturer, the boost pump
relay is energized, providing 24 VDC to activate the
boost pump.

2.3.5 Vent Mode

Once the temperature is satisfied, there is a window
whenthe unitwill gointoaventmode.This iswhen there
is neither heating or cooling. Only the evaporator fans
are operating. The range of the V ent mode is 2°C. or

3.6°F. from the set point. The compressor clutch is
disengaged at this time.

2.3.6 Compressor Unloader Control (Only with

05G or 05K Compressors)

When operating in cooling, the unloaders are used to
reduce system capacity as return air temperature
approaches set point. Operation of the unloaders
balances system capacity with the load and thereby
prevents overshoot from set point.

Relay Board mounted unloader outputs control the
capacity of the compressor by energizing or
de--energizing unloader solenoid valves. The model
05Gcompressorhasthree banks oftwocylinders each.
Enercizingavalvede--activates abankofcylinders. The
outboard cylinder banks of the 05G are equipped with

unloader valves (UV1 and UV2), each controlling two
cylinders; this allows the 05G to be operated with two,
four or six cylinders.

The unloaders are used to control system capacity by
controlling compressor capacity.

Control of the unloaders is with the pressure switches.

a. Suction Pressure

The unloaders areusedtocontrolsuction pressure and
thereby prevent coil frosting:

1. Compressor Unloader UV1 Relay

-- When the suc­tion pressure decreases below 26 psig (R--134a),
unloader UV1 is energized, unloading a cylinder
bank (2 cylinders); this output will remain energized
until the pressure increases to above 34 psig
(R--134a).

2. Compressor Unloader UV2 Relay

-- When suction
pressure decreases below 23 psig (R--134a), un­loaderUV2is energized, unloadingthe secondcom­pressor cylinder bank; this output will remain ener­gized until the pressure increases to above 31 psig
(R--134a).

b. Discharge Pressure

Discharge pressure is also controlledbytheunloaders:

1. Compressor Unloader UV1 Relay

-- When the dis­charge pressure increases above setpoint A (see
Table 2.1), unloader UV1 isenergized;thisunloader
will remain energized until the pressure decreases
below set point B (see Table 2.1).

Table 2.1 Unloader UV1 Relay

HP Switch

(PSIG)

Set Point A

(PSIG)

Set Point B

(PSIG)

300 (R--134a) 275 220
350 (R--134a)

(High Ambient)

325 270

2. Compressor UnloaderUV2Relay -- On R--134asys­tems when the discharge pressureincreasesabove
setpoint A (see Table 2.2), unloader UV2 is ener­gized; this unloader will remain energized until the
pressure decreases below set point B (see
Table 2.2).

Table 2.2 Unloader UV2 Relay

HP Switch

(PSIG)

Set Point A

(PSIG)

Set Point B

(PSIG)

300 (R--134a) 285 225
350 (R--134a)

(High Ambient)

330 275

2.3.7 Override Mode -- AC310 (Dehumidification)

Wheninthe heatmodethe compressor willnotoperate.
The thermostat will allow only COOL, VENT or HEAT
modes independently. An override switch has been
installedin the return air area toallow the compressors
torunwhen intheHEATmode.Moving the switch tothe
ON position will energize both clutch relays energizing
the clutches. There are two temperature sensors that
are in series with the clutch relay circuit, Ambient
Sensor (mounted in the condenser) and Humidity
Control Sensor (mounted inthereturnair area). As long
as the return air temperature is above 60° F and the
ambient is above 25° F,the override circuit will function
when energized, providing dehumidification. (See
section 1.4 for sensor specs)

T--304 04/08

2--2

2.3.8 Evaporator Fan Speed Selection

Evaporator fan speed(s) selection is one method of
controlling the cooling and heating throughout the bus
passenger compartment. The thermostat control is the
other.

2.3.9 Compressor Clutch Control
(A--6, TM--16, TM--21)

A belt driven electric clutch is employed to transmit
engine power to the air conditioning compressor.
De-energizing the clutch’s electric coil disengages the
clutch and removes power from the compressor. The
clutch will be engaged when in cooling and disengaged
whenthesystem is off,inheatingor duringhighand low
pressure conditions.

The clutch coil will be de-energized if the discharge
pressure rises to the 365 ±10 psig (19.42 bar) cutout
setting of the compressor mounted high pressure
switch. The clutch coilwillenergize (AutomaticRe--Set)
when the discharge pressure falls to 280 ± 10 psig
(11.41 bar).

The clutch coilwillbe de-energized (open) if the suction
pressure (LP) decreasesbelow6± 3psig (0.45 bar).
The clutch coil will energize (Automatic Re--Set) when
suction pressure rises (close)to 25 ± 3 psig (1.7 bar).

2.4 SEQUENCE OF OPERATION (280P / 282P)

2.4.1 Electronic Thermostat

With a signalfromtheHydraulicBrakeModule (or other
12 VDC source) the A/C Power Relay is grounded,
sending 12 VDC to the K1A relay. K1A relay energizes
sending battery power (Line B+) to the Dash Control
switches (S1A & S2A).

Begining with the Fan Speed Switch (S1A) in the low
speed position (vent 1)thefollowingactions takeplace:

a. Power flows from the Fan Speed Switch (S1A)

through relay K4A normally closedcontacts. Line U2
energizes evaporator fan motor low speed relays
(K1M, K4M, K7M & K10M). Closing these relays al­lows power to flow from the battery(line B+) through
the fan motors with two motors in series, operating
the motors at low speed.

b. The ON/OFF switch (S2A) is then placed in the ON

position. Power flows fromtheswitchtoenergizethe
Thermostat. With the Thermostat calling for cooling,
power also flows from the cooling switch:

1. Thorugh theHumidity ControlSensorandtheAmbi­ent Sensor Switches located in the return air and
condenser respectively.If both oftheseswitchesare
in the closed position the following sequence will
take place.

2. Power will flow to the Clutch Lockout Relays (CLR1
& CLR2) allowing power to energize the Clutch Re­lays (CR1 & CR2). Relays CR1 & CR2 are powere­don terminal 30 from an OEM breaker, (A/C Low
Voltage Breaker). Energizing these relays will send
power through the high and low pressure switches
and to both compressor clutches energizing the
clutch coils and starting the compressor.

3. To the liquid line solenoids (Y1A & Y2A) to start the
flow of refrigerant.

4. Through line U3, to energize the condenser fan re­lays (K14M & K15M). Energizing these relays will
send B+ power to start the condenser fan motors.

The unit is now in low speed cooling.

5. To bring the evaporator fans to high speed the fan
speed switch (S1A) is placed in the HIGH (Vent 2)
position.Powerflows fromtheswitchthroughlineU5
to energize the high speed relay (K13M). The nor­mally closed low speed relay (K4A) is de--energized
opening the low speed circuit. Power flows fromthe
high speed relay (K13M) to energize thehighspeed
fan relays (K2M, K3M, K5M, K6M, K8M, K9M,
K11M,& K12M). Energizingtheserelays individually
grounds eachevaporator fanmotorseparately plac­ing them in high speed operation.

c. With the thermostat calling for heating, power flows

from the heat switch:

1. Through line UH to energize the heat relay (K3A).
With the heat realy energized, power flows from the
battery (line B+) to start the water pump and open
theheatvalve.The unitisnow intheheat mode. Fan
speeds can be adjusted the same as in the cooling
mode.

d. With the Thermostat calling for Heating and the need

for Dehumidification is required:

1. The override switch, located in the return air inlet is
switched to the ON position.

2. Power will flow through the ambient and humidity
controlswitch,if closed, andenergize thecoolingcir­cuits at the same time as heating.

This will put the system in a Reheat Mode of operation.
The thermostat willonlycycle the heat valveandpump.
The cooling circuit will stay energized as long as the
override switch is in the ON position and both sensor
switches are closed.

CONTROL ACTION -- CYCLING CLUTCH

RISING

TEMPERATURE

FULL­COOL

+1.8° F ABOVE

SETPOINT

SETPOINT

VENT

SETPOINT

-- 1. 8° F ABOVE
SETPOINT

HEAT

FALLING

TEMPERATURE

Figure 2.2 280P / 282P Thermostat

2--3

T--30404/08

SECTION 3

OPERATION BT324 CONTROLLER

3.1 STARTING, STOPPING AND OPERATING
INSTRUCTIONS

The BT324 Carrier Sutrak Digital Display (CSDD) is
marked with international symbols (See Figure 3--2).

Before starting, electrical power must be availablefrom
the bus power supply (See Figure 3--1).

A 150 Amp @12 VDC or a125 Amp @ 24 VDC fuse in
the battery compartment passes power for the clutch,
evaporator and condenser assemblies.

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

3.1.1 Starting

a. If the engine is not running, start the engine.
b. When the 12/24VDC power is applied, thedriverdis-

play will illuminate and show return air set point.
Press the A/C key (Item 5 Figure 3--2) on the display
to trigger the start up sequence.

c. After the pre--trip inspection is completed, the

switches may be set in accordance with the desired
control modes.

3.1.2 Stopping

A/C

Toggling the A/C key (Item 5 Figure 3--2)onthedisplay
again will stop the system operation.

3.2 PRE--TRIP INSPECTION

After startingsystem,allow systemtostabilizefor tento
fifteen minutes and check for the following:

a. Listen for abnormal noises in compressoror fan mo-

tors.
b. Check compressor oil level (05G Compressor only).
c. Check refrigerant charge. (Refer to section 5.8.1 )

3--1

T--30404/08

1

6

5432

10987

KEYS

Figure 3--2 BT324 CSDD Controller

1. Plus Key

2. Minus Key

3. Recirculate/Fresh Air Key

4. Blower Control Key

5. Automatic Climate Control (A/C)

3.3 SEQUENCE OF OPERATION BT324 CSDD

3.3.1 Function of Keys when “Engine On” and
controller active:

a. Plus Key-- Increasesinteriortemperaturesetpointby

1° per stroke or increases manual blower speed, de­pending on displayed mode.

b. Minus Key -- Decreasesinteriortemperaturesetpoint

by 1° per stroke or decreases manual blower speed,
depending on displayed mode.

c. Recirculating Air/Fresh Air -- Switches from Recircu-

lating Air to Fresh Air and vice--versa.

d. Blower Control-- Switcheson themanual blowercon-

trol.

e. Automatic Climate Control -- Switches on the Auto-

matic Temperature Control.

f. Temperature Indicator (Key2+Key3)-- Shows the

inside temperature for 10 seconds. If pressed a sec­ond time shows the outside temperature for 10 sec­onds (optional).

g. Reheat (optional) (Key3+Key5)-- Starts Reheat

mode for 3 minutes (duration adjustable).

h. Controller Off (A/C Switch ToOff) -- Switches off all

control functions and the display.

LEDS

6. Display

7. Fresh Air Operation (Green)

8. Manual Blower Control ’ON’ (Green)

9. Heating Mode (Green)

10. Malfunction Light (Red)

NOTE

The following blower steps are disabled when
the automatic climate control is on:
2--, 3--step blower: Off
Continuously adjustable blower: Off

3.3.2 Illuminating Indications (Display)

With “Engine--On” and Controller active

3.4 Operating Instructions BT324

Whentheengine is running, toggletheA/CSwitch to on
to activate the Air Conditioning Unit.

3.4.1 Display

When the unit is ON, the display shows the interior
setpoint temperature. When selecting individual
functions, the display shows the corresponding
information forashort periodoftime. Thedisplayisdark
when the engine and control unit are OFF.

3.4.2 Interior Temperature Control

Press the Plus (1) or Minus (2) keys to set the desired
interior temperature.

Thetemperaturecanbeadjustedbetween 64° F(18° C)
and 82° F(28° C).

When the outside temperatures are below 35° F(2° C)
(adjustable parameter), the cooling function remains
disabled.

3.4.3 Ventilation

When the unitisoperatinginAutomaticClimateControl
mode, theblower speed iscontrolled basedon theroom
temperature.

T--304

3--2

04/08

However,theblowers maybeswitched tomanualmode
of operation by pressing the blower key.

Press the Plus orMinuskeys to define oneof 5 different
blower steps. The blowers can not be switched OFF
when Automatic Climate Control is ON.

When Automatic Climate Control is OFF, the blowers
stop when the manual control is turned to zero.

3.4.4 Reheat (optional)

The Reheat modeisused to remove air humidity and to
help defog the windshield. Press Key 3 (Recirculating
Air/FreshAir) and Key 5(Automatic Climate Control) at
the same time to activate Reheat. Heating and cooling
will be energized on for 3 minutes (adjustable
parameter). In addition, the blowers are switched to
maximum speed and the fresh air flap is closed. At the
end of the pre--set duration of time,the functions return
to the previously selected settings.

Reheatmodeisdisabledwiththeoutside temperatureis
below 35° F(2° C) (adjustable parameter), when the
sensor is notinstalled, orwhenthereis a sensorfailure.

3.4.5 Temperature Indication

Presskey2 (minus) and key3(RecirculatingAir/Fresh
Air) at the same time to display the inside temperature
for 10 seconds.

Optionally, the outside temperature may be displayed
when pressing the keys a second time.

A sensor malfunction is displayed by “ i -- -- ” or “ o -- -- ” .

3.5 CHANGING BETWEEN °F (FAHRENHEIT)
AND °C(CELCIUS)

Procedures for changing theBT324Controllerbetween
Fahrenheit and Celcius is as follows:

a. Engine “OFF” & Ignition “ON”.
b. Press Key 1 (plus) and Key 2 (minus) at the same

time until the display shows the word “Code”.

NOTE

After the display shows the word “Code” you
have 5 seconds to enter the correct access
code.

c. Press Key 1 (Plus Key) one time and release.
d. Press Key 3 (Recirculating Air/Fresh Air) one time

and release.
e. Press Key 4 (blower control) one time and release.
The display will show the mode “Fah” for temperatures

in °F or the mode “Cel” for temperatures in °C.
f. Press Key 1 (plus) or Key 2 (minus) to change the

temperature mode.
g. Press Key 5 (automatic climate control) one time to

end the program.

3--3

T--30404/08

SECTION 4

TROUBLESHOOTING

Table 4-- 1 General System Troubleshooting Procedures

INDICATION --

TROUBLE

4.1 System Will Not Cool

Compressor will not run Drive--Belt loose or defective

Electrical malfunction Coach power source defective

4.2 System Runs But Has Insufficient Cooling

Compressor Drive-Belt loose or defective

Refrigeration system Abnormal pressures

Restricted air flow No evaporator air flow or restriction 4.5
Heating system Heat valve stuck open 4.7

4.3 Abnormal Pressures

High discharge pressure Refrigerant overcharge

Low discharge pressure Compressor valve(s) worn or broken

High suction pressure Compressor valve(s) worn or broken SeeTable1--3
Low suction pressure Suction service valve partially closed

Suction and discharge pressures
tend to equalize when system is
operating

4.4 Abnormal Noise Or Vibrations

Compressor Loose mounting hardware

Clutch coil defective
Clutch malfunction
Compressor malfunction

Circuit Breaker/safety device open

Compressor valves defective

No or restricted evaporator air flow
Expansion valve malfunction
Restricted refrigerant flow
Low refrigerant charge
Service valves partially closed
Safety device open
Liquid solenoid valve stuck closed

Noncondensable in system
Condenser motor failure
Condenser coil dirty

Low refrigerant charge

Filter-drier inlet valve partially closed
Filter-drier partially plugged
Low refrigerant charge
Expansion valve malfunction
Restricted air flow

Compressor valve defective SeeTable1--3

Worn bearings
Worn or broken valves
Liquid slugging
Insufficient oil
Clutch loose, rubbing or is defective
Drive-Belt cracked, worn or loose
Dirt or debris on fan blades

POSSIBLE CAUSES

REFERENCE

SECTION

Check
Check/Replace
Check/Replace

SeeTable1--3

Check/Repair

Check/Reset

Check

SeeTable1--3

4.3

4.5

4.6

5.11

5.8

Open

1.5

5.13

5.8.1
Check
Check

Clean

SeeTable1--3

5.8

Open

Check/Open

5.11

5.8

4.6

4.5

Check/Tighten
SeeTable1--3

SeeTable 1--3

4.6

1.3
Repair/Replace
Adjust/Replace

Clean

04/08

4--1

T-304

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

INDICATION --

TROUBLE

POSSIBLE CAUSES

REFERENCE

SECTION

4.4 Abnormal Noise Or Vibrations -- Continued

Condenser or evaporator fans Loose mounting hardware

Defective bearings
Blade interference
Blade missing or broken

Check/Tighten

Replace

Check

Check/Replace

4.5 No Evaporator Air Flow Or Restricted Air Flow

Air flow through coil blocked Coil frosted over

Dirty coil
Dirty filter

No or partial evaporator air flow Motor(s) defective

Motor brushes defective
Evaporator fan loose or defective
Fan damaged
Return air filter dirty
Icing of coil
Fan relay(s) defective
Safety device open
Fan rotation incorrect

Defrost coil

Clean

Clean/Replace

Repair/Replace

Replace
Repair/Replace
Repair/Replace

Clean/Replace

Clean/Defrost

Check/Replace

1.5

Check

4.6 Expansion Valve Malfunction

Low suction pressure with high
superheat

Low superheat and liquid slugging
in the compressor

Low refrigerant charge
Wax, oil or dirt plugging valve orifice
Ice formation at valve seat
Power assembly failure
Loss of bulb charge
Broken capillary tube

Bulb is loose or not installed.
Superheat setting too low

5.8

Check

4.6
Replace
Replace

5.16

5.16

5.16

Ice or other foreign material holding valve open

Side to side temperature differ­ence (Warm Coil)

Wax, oil or dirt plugging valve orifice
Ice formation at valve seat
Power assembly failure
Loss of bulb charge
Broken capillary

Check

5.7
Replace
Replace

5.16

4.7 Heating Malfunction

Insufficient heating Dirty or plugged heater core

Coolant solenoid valve(s) malfunctioning or plugged
Low coolant level
Strainer(s) plugged
Hand valve(s) closed
Water pumps defective
Auxiliary Heater malfunctioning.

No Heating Coolant solenoid valve(s) malfunctioning or plugged

Controller malfunction
Pump(s) malfunctioning
Safety device open

Clean

Check/Replace

Check

Clean

Open
Repair/Replace
Repair/Replace

Check/Replace

Replace

Repair/Replace

1.5

Continuous Heating Coolant solenoid valve stuck open 5.12

T--304

4--2

04/08

SECTION 5

SERVICE

WARNING

Besure toobservewarnings listed inthesafetysummaryin thefront ofthis manual beforeperform­ing maintenance on the hvac system

WARNING

Read the entire procedure before beginning work. Park the coach on a level surface, with parking
brake applied. T urn main electrical disconnect switch to the off position.

NOTE

To avoid damage to the earth’s ozone layer, use a refrigerant recovery system whenever removing refriger­ant. The refrigerant recovery system isavailablefromCarrier Transicold (CarrierTransicoldP/NMVSII--115
orMVSII--240).Whenworkingwithrefrigerants youmustcomplywithall localgoverment environmental laws.

5.1 MAINTENANCE SCHEDULE
SYSTEM

ON OFF

a. Daily Maintenance

X

b. Weekly Inspection

X

c. Monthly Inspection and Maintenance

5.2 REMOVING EVAPORATOR COVER

To remove the evaporator cover do the following:

1. Turn all the 1/4 turn cam locks counterclockwise.

2. Using two people carefully grasp the cover under the

bottom edge and lift up.

3. Place the evaporator cover on top of the condenser

section.

5.3 REMOVING CONDENSER COVER

To remove the condenser cover do the following:

1. Turn all the 1/4 turn cam locks counterclockwise.

2. Using two people carefully grasp the cover under the

bottom edge and lift up.

Pre-tripInspection -- after starting

X

Check tension and condition of drive belts.

X

Perform daily inspection

X

Check condenser, evaporator coils and air filters for cleanliness

X

Check refrigerant hoses, fittings and component connections for leaks
Feel filter-drier for excessive temperature drop across drier

X

Perform weekly inspection and maintenance

X

Clean evaporator drain pans and hoses

X

Check wire harnesses for chafing and loose terminals

X

Check fan motor bearings

X

Check compressor mounting bolts for tightness

SYSTEM

REFERENCE

SECTION

2.2
None

See above
None

5.6

5.11

See above
None
Replace/Tighten
None
None

3. Place the condenser cover on top of the evaporator
section.

5.4 INSTALLING MANIFOLD GAUGE SET

A manifold gauge set can be used to determine system
operating pressures, add charge, equalize or evacuate
system.

When the suction pressure hand valve is frontseated
(turned alltheway in),thesuction(low) pressure can be
read. When the discharge pressure hand valve is
frontseated, discharge (high) pressure can be read.
When both valves are open (turnedcounterclockwise),
high pressure vapor will flow into the low side. When
only the low pressure valve is open, the system can be
charged or evacuated.

04/08

5--1

T-304

CAUTION

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

SUCTION
PRESSURE
GAUGE

1.

DISCHARGE
PRESSURE
GAUGE

5.4.1 Installing R--134a Manifold Gauge/Hose SET

An R--134a manifold gauge/hose set with self--sealing
hoses is pictured in Figure 5--1. The manifold
gauge/hose set is available from Carrier Transicold.
(Carrier Transicold P/N 07--00294--00, which includes
items1through6,Figure 5--1).Toperform serviceusing
the manifold gauge/hose set, do the following:

a. Preparing Manifold Gauge/Hose Set for use.

1. If the manifold gauge/hose set is new or was ex­posedtothe atmosphere itwillneed tobe evacuated
to remove contaminants and air as follows:

2. Back--seat (turncounterclockwise) bothfieldservice
couplers (see Figure 5--1) and mid--seat both hand
valves.

3. Connect the yellow hose to a vacuum pump and an
R--134a cylinder.

4. Evacuate to 10 inches of vacuum and then charge
with R134a to slightly positive pressure of 1.0 psig.

5. Front--seatbothmanifold gaugeset handvalvesand
disconnect from cylinder. The gauge set is now
ready for use.

OPENED
(Backseated )
HAND VALVE

To Low Side
Access Valve

3.

BLUE

2.

4.

6.

Blue Knob

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

1. Manifold Gauge Set

2..Hose Fitting (0.5-16 Acme)

3..Refrigeration and/or Evacuation Hose
. (SAE J2196/R-134a)

4..Hose Fitting w/O-ring (M14 x 1.5)

5..High Side Field Service Coupling

6..Low Side Field Service Coupling

To Refrigerant Tank

or Vacuum Pump

2.

RED

3.

YELLOW

To High Side
Access Valve

3.

CLOSED
(Frontseated)
HAND VALVE

4.

5.

Red Knob

b. Connecting the Manifold Gauge Gauge/Hose Set.
To connect the manifold gauge/hose set for reading

pressures, do the following:

1. Connect the field service couplers (see Figure 5--1)
to the high and low in--line service ports.

2. Turn the field service coupling knobs clockwise,
which will open the system to the gauge set.

3. Read the system pressures.

c. Removing the Manifold Gauge Set.

1. While the compressor is still ON, mid--seat both
hand valvesonthe manifold gaugesetand allow the
pressureinthemanifoldgauge settobedrawndown
tolowside pressure. Thisreturnsanyliquidthatmay
be in the high side hose to the system.

CAUTION

To prevent trapping liquid refrigerant inthe
manifoldgaugesetbesuresetis broughtto
suction pressure before disconnecting.

2. Back--seatbothfield servicecouplersand front--seat
bothmanifoldsethand valves.Removethe couplers
from the in--line access valves.

3. Install both in--line access valve caps.

T-304

5--2

04/08

5.5 PUMPING THE SYSTEM DOWN OR REMOV­ING THE REFRIGERANT CHARGE

NOTE

Toavoid damagetothe earth’sozone layer,use
arefrigerant recoverysystemwheneverremov­ing refrigerant.

5.5.1 System Pump Down For Low Side Repair

To service or replace the filter--drier, pump the
refrigerant to the condenser and receiver as follows:

a. Remove evaporator and condenser covers.
b. Install manifold gauge/hose set. (Refer to Section

5.4.1).

c. Frontseatthefilter--drierinlet servicevalve by turning

clockwise. It will be necessary to install a jumper
across the low pressure switch(LPS) contacts at the
compressor in order to reach 0 PSIG.

d. Start the system and run in cooling. Stop the unit

when suction reaches 10 ”/hg (25.4 cm/hg) vacuum.

e. Frontseat filter/drieroutletservicevalve to traprefrig-

erantin thehighsideofthesystem betweenthe com­pressor andthefilter--drierinlet valve. Wait 5minutes
to verify that system remains in a vacuum.

f. Service or replace filter--drier.

1.

D

S

2.

To Compressor

7.

6.

Figure 5--2 In--Line Service Connections

1. Discharge Service
Port

2. Suction Service
Port

3. Manifold Gauge

4. Vacuum Pump

5. Reclaimer

6. Refrigerant Cylinder

7. Thermistor Vacuum
Gauge

Set

3.

4.

5.

g. Leak check connections after replacing filter--drier.

Refer to paragraph 5.6.

h. Usingrefrigeranthoses designedfor vacuumservice,

evacuateanddehydrate thefilter--drierby connecting
a vacuum pump to center connection of manifold
gauge set. Evacuate system to 500 microns. Close
off pump valve, isolate vacuum gauge and stop
pump. Wait 5 minutes to verify that vacuum holds.

i. Read MicronGaugeagainto verify that the pressure

did notrisemorethan500 microns within that 5--min­ute timeframe.

If the Micron Gauge rises more than 500 microns (to
excedeagaugereading of500 +500 =1000 microns) at
the end of 5 minutes, either a leak is present or an
unacceptable level of moisture remains in the circuit. If
the gauge reads a gain of less than 500 microns during
the5--minutewait, the circuit isacceptablytightanddry.

j. Oncevacuum is maintained, recharge systembyad-

mitting vapor from the refrigerant cylinder.

k. Remove manifold gauges. Backseat both filter drier

service valves.

5.5.2 Removing Entire System Charge

To remove the entire refrigerant charge, do the
following:

a. Connect a manifold gauge set to the system as

showninFigure5--2.

b. Connect a reclaimer tothecentermanifoldgauge set

connection.

c. Recover refrigerant in accordance with reclaimer

manufacturers instructions.

5.6 REFRIGERANT LEAK CHECK

A refrigerant leak check should always be performed
after the systemhasbeenopened to replaceorrepaira
component.

To check for leaks in the refrigeration system, perform
the following procedure:

NOTE

It must be emphasizedthat only the correct re­frigerant should be used to pressurize the sys­tem. Use of any other refrigerant will contami­nate the system, and require additional
evacuation.

a. Ensure filter drier service and solenoid valves are

open.

1. Filter drier service valves should be back seated.
b. If system is without refrigerant, charge system with

refrigerant vapor to build up pressure between 20 to
30 psig (1.36 to 2.04 bar).

c. Add sufficient nitrogen to raise system pressure to

150 to 200 psig (10.21 to 13.61 bar).

d. Check for leaks. The recommended procedure for

findingleaksina systemis withanelectronicleakde­tector. Testing joints with soapsuds is satisfactory

only for locating large leaks.
e. Remove test gas and replace filter--drier.
f. Evacuate and dehydrate the system. (Refer to para-

graph 5.7.)
g. Charge the unit. (Refer to paragraph 5.8.)

5.7 EVACUATION AND DEHYDRATION

5.7.1 General

04/08

5--3

T-304

The presence of moistureinarefrigeration system can
have many undesirable effects. The most common are
copper plating, acid sludge formation, “freezing-up” of
metering devices by freewater, and formation of acids,
resulting in metalcorrosion. An evacuation shouldtake
place after a system repair (replacement of filter drier.
expansion valve, solenoid valve, etc).

5.7.2 Preparation
NOTE

Using a compound gauge (manifold gauge) for
determination of vacuum level is not recom­mended because of its inherent inaccuracy.

a. Evacuate anddehydrate onlyafter pressureleaktest.

(Refer to paragraph 5.6)

b. Essential tools to properly evacuate and dehydrate

anysysteminclude agood vacuumpumpwith amini­mumof5cfm(8.5 m

3

/hr)volumedisplacement,(CTD

P/N 07-00176-11), and a good vacuum indicator
(CTD P/N 07--00414--00).

c. Keep the ambient temperature above 60°F (15.6°C)

to speed evaporation of moisture. If ambient temper­ature is lower than 60°F (15.6°C), ice may form be­fore moisture removal is complete.

5.7.3 Procedure for Evacuation and Dehydrating

System

a. Removerefrigerant usingarefrigerant recovery sys-

tem. Refer to paragraph 5.5.2

b. Therecommendedmethod isconnecting3/8”OD re-

frigerant hoses designed for vacuum service as

shown in Figure 5--3.
c. Make sure vacuum pump valve is open.
d. Start vacuum pump. Slowly open valves halfway and

then open vacuum gauge valve.
e. Evacuate unit until vacuum gauge indicates 500 mi-

crons Hgvacuum. Closegaugevalve, vacuum pump

valve, and stop vacuum pump.
f. Close off pump valve, and stop pump. Wait five min-

utes to see if vacuum holds.
g. Charge system. Refer to paragraph 5.8.2

5.8 ADDING REFRIGERANT TO SYSTEM

5.8.1 Checking Refrigerant Charge

The following conditions must be met to accurately
check the refrigerant charge.

a. Bus engine operating at high idle.
b. Unit operating in cool mode for 15 minutes.
c. Compressor discharge pressure at least 150 psig

(10.21 bar). (It may benecessary toblockcondenser

air flow to raise discharge pressure.)

NOTE

Ideal charging conditions are with ambient
above 86°F(30°C) and interior vehicle temper-
ature above 77°F(25°C). Charging to a full
sight glass at lower temperatures may lead to
system overcharge.

d. Under the above conditions, the system is properly

chargedwhenthe liquidlinesight glaseshows full(no
bubbles present).

5.8.2 Adding Full Charge

a. Install manifold gauge set at the in--line suction and

discharge service ports.

b. Evacuateanddehydratesystem.(Refertoparagraph

5.7)

c. Placeappropriaterefrigerant cylinder onscales.Pre-

pare tochargeliquidrefrigerantby connectingcharg­inghosefrom container tocenterconnectionon gage

manifold. Purge air from hoses.
d. Note weight of refrigerant and cylinder.
e. Open cylinder valve, backseat discharge valve on

gaugemanifoldandallow liquidrefrigerantto flowinto

the high side of the system
f. When correct charge has been added (refer to para-

graph 1.3, refrigerant specifications), close cylinder

valve and frontseat manifold discharge valve.
g. Preparethecylinder asrequired toallowvaporcharg-

ing. Backseat the manifold suction valve and charge

vapor until thecorrect chargehasbeen added. Close

cylinder valve and frontseat suction manifold set.
h. Check charge level in accordance with the proce-

dures of paragraph 5.8.1.

5.9 CHECKING FOR NONCONDENSIBLES

To check for noncondensibles, proceed as follows:
a. Stabilize system to equalize pressure between the

suction and discharge side of the system.
b. Check temperature at the condenser and receiver.
c. Check pressure at the discharge (in--line) service

port.
d. Check saturation pressure as it corresponds to the

condenser/receiver temperature. See temperature--

Pressure chart Table Table 5--1. for R134a.
e. If gauge readingis3 psig or more than the calculated

P/T pressure in step d., noncondensables are pres-

ent.
f. Removerefrigerant usingarefrigerant recovery sys-

tem.
g. Evacuate and dehydrate the system. (Refer to para-

graph 5.7.)
h. Charge the unit. (Refer to paragraph 5.8.2.)

5.10 CHECKING AND REPLACING HIGH OR LOW-

PRESSURE CUTOUT SWITCH

5.10.1 Replacing High Or Low Pressure Switches

a. The high and low pressure switches are equipped

withschradervalvestoallow removal andinstallation

without recovering the refrigerant charge.
b. Disconnect wiring from defective switch.
c. Install new cutout switch after verifying switch set-

tings.

T-304

5--4

Change 07/09

5.10.2 Checking High Or Low Pressure Switches

WARNING

5.11 FILTER-DRIER

Do not use a nitrogen cylinder without a pres­sure regulator

WARNING

Donot useoxygeninornear arefrigerationsys­tem as an explosion may occur.

a. Disconnect wiring and remove switch from system.
b. Connect an ohmmeter across switch terminals. If the

switch is good, the ohmmeter will indicate no resist­ance, indicating that the contacts are closed.

c. Connect switch to a cylinder of dry nitrogen.

(SeeFigure 5--4).

1.

4.

2.

3.

5.

6.

2. 3. 4.

1.

Figure 5--5 Filter--Drier Removal

1. Filter-Drier Inlet
Service Valve

2. Valve Service Port

3. Flare Nut

4. Filter-Drier

5.11.1 To Check Filter--Drier

Thefilter--drier(SeeFigure 5--5)mustbechanged ifthe
system has been opened, (for any reason), or the filter
drier is partially restricted. Restriction can be identified
by either the outlet frosting or a temperature difference
between the inlet and outlet.

5.11.2 To Replace Filter--Drier Assembly

Filter Drier replacement can be accomplished by
performing either one of the two procedures
recommended.

1. System operating,lowsidepumpdown (refertosec­tion 3.4.1).

2. System not operating (see below).

a. Turn the driver’s A/C switch to “OFF” position.
b. Frontseat the filter--drier servicevalveson bothsides

of the filter drier.

c. Place a new filter-drier near the unit for immediate

installation.

3.

5. Liquid Line

6. Filter-Drier Outlet

2.

Solenoid Valve
Service Valve

6.

5.

Figure 5--4 Checking High Pressure Switch

1. Cylinder Valve and Gauge

2. Pressure Regulator

3. Nitrogen Cylinder

4. Pressure Gauge (0 to 400 psig = 0 to 27.22 bar)

5. Bleed-Off Valve

6. 1/4 inch Connection

d. Set nitrogen pressure regulator higher than switch

cutout setting. (refer to paragraph 1.3.)

e. Open cylinder valve. Slowlyopentheregulator valve

to increase the pressureuntil it reaches cutout point.
The switch shouldopen,whichis indicated by an infi­nite reading on an ohmmeter (no continuity).

f. Close cylinder valve and release pressure through

the bleed--off valve. As pressure drops to cut--in
point, the switchcontacts should close, indicatingno
resistance (continuity) on the ohmmeter.

g. Replace switch if it does not function as outlined

above.

WARNING

The filter-drier may contain liquid refriger­ant.Slowlyloosentheconnectingnuts and
avoid contact with exposed skin or eyes.

d. Using two openendwrenches, slowly crack openthe

connecting nuts on each side of the filter-drier as­sembly. Remove the filter-drier assembly.

e. Remove seal caps from the new filter-drier. Apply a

light coat of mineral oil to the filter--drier connections.

f. Assemblethenewfilter-driertolinesensuringthatthe

arrowonthe bodyofthefilter-drierpointsin the direc­tion of the refrigerant flow (refrigerant flows from the
receiver to the evaporator). Finger tighten the con­necting nuts.

g. Tighten filter-drier connecting nuts using two open

end wrenches.
h. Evacuate system (refer to section 5.7).
i. Backseat(fullyclose) bothservicevalveports andre-

place valve caps.
j. Check refrigerant charge (refer to section 5.8.1).
k. Remove Gauges.

04/08

5--5

T-304

5.12 SERVICING THE HEAT VALVE

f

f

The heat valve (Figure 5--6) requires no maintenance
unless a malfunction to theinternalparts or coiloccurs.
This may be caused by foreign material such as: dirt,
scale, or sludge in the coolant system, or improper
voltage to the coil.

1. Coil Retaining Screw

2. Nameplate

3. Coil Housing
Assembly

4. Enclosing Tube &
Bonnet Assembly

5. Kick-O

6. Plunger

7. Closing Spring

8. Diaphragm

9. O-Ring

10. Valve Body

Spring

NOTE

TheOEMsuppliedheating(hot water)Solenoid
Valve is normally located outside of the
AC310/350 rooftop air conditioning system.

There are only three possible valve malfunctions: coil
burnout, failure to open, or failure to close.

Coil burnout may be caused by the following:

1. Improper voltage

2. Continuous over-voltage, more than 10% or Under­voltage of more than 15%.

3. Incomplete magneticcircuitduetotheomissionofthe
coil housing or plunger.

4. Mechanical interference with movement of plunger
which may be caused by a deformed enclosing tube.

Failure to open may be caused by the following:

1.Coil burned out or an open circuit to coil connections.

2. Improper voltage.

3. Torn diaphragm.

4. Defective plunger or deformedvalvebodyassembly.

Failure to close may be caused by the following:

1. Defective plungerordeformedvalve bodyassembly.

2. Foreign material in the valve.

3. Torn diaphragm.

1.

2.

5.12.1 Coil Replacement

a. It is not necessary to drain the coolant from the sys-

tem.

b. Place mainbatterydisconnectswitchin OFF position

and lock.
c. Disconnect wire leads to coil.
d. Remove coil retaining screw and nameplate.
e. Lift burned-out coil from enclosing tube and replace.
f. Connect wire leads and test operation.

5.12.2 Internal Part Replacement

a. Disconnect system from bus battery.
b. Open the vent fitting atthetopoftheoutlet headerof

the heater coil.
c. Draincoil by opening thedrain-cock ontheinlet tube.
d. Disassemble valve and replace defective parts.
e. Assemble valve, refill and bleed coolant lines.

5.12.3 Replace Entire Valve

a. Disconnect system from bus battery.
b. Drain coolant fromlines as previously described and

disconnect hoses to valve .
c. Disconnect wire leads to coil.
d. Remove valve assembly from bracket.
e. Install new valve and re-connect hoses. It is not ne-

cessarytodisassemblethe valvewheninstalling.
f. Refill and bleed coolant lines.
g. Connect wire leads and test operation.

T-304

3.

4.

5.

6.

7.

8.

9.

10.

Figure 5--6 Heat Valve

5.13 SERVICING THE LIQUID LINE SOLENOID

VALVE

The Liquid line solenoid valve (Figure 5--7) is very
similar to the heat valve. It requires no maintenance
unless a malfunction to theinternalparts or coiloccurs.
This may be caused by foreign material such as: dirt,
scale, orsludgein the refrigeration system, or improper
voltage to the coil.

There are only three possible valve malfunctions: coil
burnout, failure to open, or failure to close.

Coil burnout may be caused by the following:

1. Improper voltage.

2. Continuous over-voltage, more than 10% or under-

voltage of more than 15%.

3. Incomplete magnet circuit due to the omission of the

coil hosing or plunger.

4. Mechanical interface with movement of plunger

which may be caused by a deformed enclosing tube.

5--6

04/08

Failure to open may be caused by the following:

g

y

1. Coil burnedoutoran open circuit to coil connections.

2. Improper voltage.

2.

1.

3. Defective plunger or deformedvalvebodyassembly.

Failure to close may be caused by the following:

1. Defective plunger or deformedvalvebodyassembly.

2. Foreign material in the valve.

5.13.1 Coil Replacement

a. It is not necessary to remove the refrigerant charge

from the system.
b. Disconnect system from bus battery.
c. Disconnect wire leads to coil.
d. Remove coil retaining clip and nameplate.
e. Lift failed coil from enclosing tube and replace.
f. Connect wire leads and test operation

5.13.2 Internal Part Replacement

a. Disconnect system from bus battery.

3.

4.

5.

6.

7.

8.

Figure 5--7 Liquid Line Solenoid Valve

1. Snap Cap

2. Coil Assembly

3. Enclosing Tube
Assembly

4. Plun

5.14 SERVICE V AL VES

The filter/drier (High Side) service valves (Figure 5--8)
areprovidedwith a doubleseatand agaugeport,which
allows servicing of the filter drier assembly.

er Assembl

5. Gasket

6. Piston Assembly

7. Body

8. Bracket Adapter

b. Recover and recycle system refrigerant.
c. Slowly loosen enclosing tube assembly to bleed any

remaining pressure from the valve. Disassemble

valve and replace defective parts.
d. Assemble valve and leak check.
e. Evacuate and recharge system.

5.13.3 Replace Entire Valve

a. Recover and recycle system refrigerant.
b. Remove valve assembly from bracket.
c. Disconnect wire leads to coil.
d. Disassemble newvalve,toprotectinternalparts,and

solder to lines.
e. Assemble and leak check valve.
f. Evacuate and recharge.system.

Turning the valve stem counterclockwise (all the way
out) will backseat the valve to open the line to the
system and close off the gauge port. In normal
operation, the valve is backseated to allow full flow
through the valve. The valve should always be
backseated before removing the gauge port cap.

Turning the valve stem clockwise (all the way forward)
will frontseat the valve to isolate the system and open
the gauge port.

TO DISCHARG LINE

Port To
Compressor

Service Valve
Frontseated
(clockwise)

Service Valve
Backseated
(counterclockwise)

VALVE CAP

SERVICE
PORT

VALVE
STEM

g. Connect wire leads and test operation.

04/08

5--7

Figure 5--8 Service Valve R134a (High Side)

T-304

5.15 REPLACING RETURN AIR FILTERS

The return air filters are located behind the return air
grill, inside the vehicle.

The filters should be checked for cleanliness
periodically depending on operating conditions. A dirty
filter will restrict air flow over the evaporator coil which
may cause insufficient cooling or heating and possible
frost buildup on the coil. To remove the filters, do the
following.

a. Insure air conditioning system is in the off position.
b. Remove the return airgrillewiththefilter--diffuseras-

sembly,byturning the six 1/4 turn fastenerscounter­clockwise.

Composit Frame

f. Pullfilterelement approximately 1/4inchover endsof

the diffuser.

Diffuser

Air Filter

Composit Frame

Figure 5--11

Filter, Diffuser and Composit Frame

g. Place filteranddiffuser intocompositframe, withfilter

element down (See Figure 5--11).

Return Air Filter

Figure 5--9 Return Air Grill Assembly

With Air Filter Showing

c. Remove diffuser from the bus composit frame.

Diffuser

Return Air Filter

Figure 5--10 Diffuser and Filter Element

d. Remove and replace the filter element.
e. Center diffuser on filter element.

Captive 1/4 Fastners

Figure 5--12 Return Air Grill Assembly

With Diffuser And Composit Frame Showing

h. Insert filter--diffuserassemblyintocomposit frameon

bus with the six captive 1/4 fasteners. (See
Figure 5--12)

i. Lock the six captive 1/4 turns in place by rotating

clockwise.

5.16 THERMOSTATIC EXPANSION VALVE

The thermostat expansion valve (Figure 5--13) is an
automatic device which maintains constant superheat
of the refrigerant gas leavingtheevaporator regardless
of suction pressure. The valve functions are: (a)
automatic control of refrigerant flow to match the
evaporator load and (b) prevention of liquid refrigerant
entering the compressor.Unless the valve is defective,
it seldom requires any maintenance.

T-304

5--8

04/08

1.

2.

3.

4.

5.

4.

6.

7.

Figure 5--13 Thermostatic Expansion Valve

1..Power Head
Assembly

2..Equalizer Connection

3..Bulb

5.16.1 Valve Replacement

a. If compressor is operative perform low side pump

down to replace expansion valve. (refer to 5.5.1) If
compressor isinoperativerecover and recycle refrig­erant from the system.(refer to 5.5.2)

b. Remove insulation from expansion valve bulb. (See

Figure 5--13 and Figure 5--14.)

c. Loosen retaining straps holding bulb to suction line

and detach bulb from the suction line.

d. Loosen flare nuts on equalizer line and disconnect

equalizer line from the expansion valve.

e. Check, clean and remove any foreign material from

the valve body,valveseatandmatingsurfaces. If re­quired, replace valve body.

4..Gasket

5..Cage Assembly

6..Body Flange

7..Cap screw

3.

2.

4.

5.

1.

Figure 5--14 Thermostatic Expansion Valve Bulb

1..Suction Line
(section view)

2..TXV Bulb Clamp

3..Nut & Bolt (clamp)

a. Open top cover.

b. Remove Presstite insulation from expansion valve

bulb and suction line.

c. Loosenone TXV bulb clamp and make sure area un-

der clamp is clean.

d. Place temperature thermocouple in contact with the

suction tube and parallel to the TXV bulb, and then
secure loosened clamp making sure both bulb and
thermocouple are firmly secured to suction line. (See
Figure 5--14). Reinstall insulation around the bulb.

e. Connect an accurate low pressure gauge to the low

pressure port.

and Thermocouple

4..Thermocouple

5..TXV Bulb (Shown
in the 4’clock
position)

NOTE

R--134a valves are adjustable. Valves are pre­setatthefactory.

f. Leak check the new valve and evacuate and dehy-

drate the system. (Refer to paragraph 5.7.)

g. The thermal bulb is installed below the center of the

suction line (four or eight o’clock position). This area
must be clean to ensure positive bulb contact. Strap
thermal bulb to suction line. Ensure that retaining

straps are tight and renew insulation.
h. Fasten equalizer line to the expansion valve.
i. Evacuate and recharge the system.
j. Run the coach for approximately 30 minutes on fast

idle.
k.Check refrigerant charge. (Refer to 5.8.1)

5.16.2 Superheat Measurement

NOTE

All readings must be taken from the TXV bulb
location and out of the direct air stream.

04/08

f. Close top cover being careful to route thermocouple

sensing wire and gauge hose outside the unit.

g. Start bus and run on fast idle until unit has stabilized,

about 20 to 30 minutes.

NOTE

Whenconductingthis test,thesuctionpressure
must be at least 6 psig (0.41bar)below theex­pansion valve maximum operating pressure
(MOP). Refer to paragraph 1.3 for MOP.

h. From the temperature/pressurechart, determine the

saturation temperature corresponding to the evapo­rator outlet pressure.

i. Notethe temperature ofthesuctiongas attheexpan-

sion valve bulb. Subtract the saturation temperature
from this temperature. The difference is the super­heat of the suction gas.

5--9

T-304

j. Thesuperheatmaycyclefromalowto high reading.

Monitorthesuperheat takingreadingsevery 3--5min­utes for a total of 5--6 readings. Calculate the super­heats, add the readings and divide by the number of

readings taken todetermine average superheat. The
superheat should be 18 ± 3°F.

k. Ifsuperheatis notwithintolerance,replacethevalve.

T-304

5--10

04/08

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

Temperature

°F °C

-- 40 -- 4 0 14.6 49.4 37.08 0.49
.35 .37 12.3 41.6 31.25 0.42

-- 30 -- 3 4 9.7 32.8 24.64 0.33

-- 25 -- 3 2 6.7 22.7 17.00 0.23

-- 20 -- 2 9 3.5 11.9 8.89 0.12

-- 18 -- 2 8 2.1 7.1 5.33 0.07

-- 16 -- 2 7 0.6 2.0 1.52 0.02

Temperature Pressure

°F °C

-- 14 -- 2 6 0.4 1.1 0.03 0.03

-- 12 -- 2 4 1.2 8.3 0.08 0.08

-- 10 -- 2 3 2.0 13.8 0.14 0.14

-- 8 --22 2.9 20.0 0.20 0.20

-- 6 --21 3.7 25.5 0.26 0.26

-- 4 --20 4.6 31.7 0.32 0.32

-- 2 --19 5.6 36.6 0.39 0.39
0 -- 1 8 6.5 44.8 0.46 0.45
2 -- 1 7 7.6 52.4 0.53 0.52
4 -- 1 6 8.6 59.3 0.60 0.59
6 -- 1 4 9.7 66.9 0.68 0.67
8 -- 1 3 10.8 74.5 0.76 0.74

10 -- 12 12.0 82.7 0.84 0.83
12 -- 11 13.2 91.0 0.93 0.91
14 -- 10 14.5 100.0 1.02 1.00
16 -- 9 15.8 108.9 1.11 1.09
18 -- 8 17.1 1 17.9 1.20 1.18
20 -- 7 18.5 127.6 1.30 1.28
22 -- 6 19.9 137.2 1.40 1.37
24 -- 4 21.4 147.6 1.50 1.48
26 -- 3 22.9 157.9 1.61 1.58

“/hg cm/hg kg/cm@ bar

psig kPa kg/cm@ bar

Vacuum

Temperature Pressure

°F °C

28 -- 2 24.5 168.9 1.72 1.69
30 -- 1 26.1 180.0 1.84 1.80
32 0 27.8 191.7 1.95 1.92
34 1 29.6 204.1 2.08 2.04
36 2 31.3 215.8 2.20 2.16
38 3 33.2 228.9 2.33 2.29
40 4 35.1 242.0 2.47 2.42
45 7 40.1 276.5 2.82 2.76
50 10 45.5 313.7 3.20 3.14
55 13 51.2 353.0 3.60 3.53
60 16 57.4 395.8 4.04 3.96
65 18 64.1 441.0 4.51 4.42
70 21 71.1 490.2 5.00 4.90
75 24 78.7 542.6 5.53 5.43
80 27 86.7 597.8 6.10 5.98
85 29 95.3 657.1 6.70 6.57
90 32 104.3 719.1 7.33 7.19

95 35 114.0 786.0 8.01 7.86
100 38 124.2 856.4 8.73 8.56
105 41 135.0 930.8 9.49 9.31
110 43 146.4 1009 10.29 10.09
115 46 158.4 1092 11.14 10.92
120 49 171.2 1180 12.04 11.80
125 52 184.6 1273 12.98 12.73
130 54 198.7 1370 13.97 13.70
135 57 213.6 1473 15.02 14.73
140 60 229.2 1580 16.11 15.80
145 63 245.6 1693 17.27 16.93
150 66 262.9 1813 18.48 18.13
155 68 281.1 1938 19.76 19.37

psig kPa kg/cm@ bar

04/08

5--11

T-304

SECTION 6

ELECTRICAL

6.1 INTRODUCTION

This section includes electrical wiring schematics. The
schematics shown in this section provides information
for theAC310 andAC350 modelrooftopair conditioning
units which are fitted with eight (8) and twelve (12)
single--shafted or four (4) and six (6) double--shafted
evaporator blower/motor assemblies and four (4) or six

UNIT

AC 310 Thermostat With Manual Reheat Figure 6--1 Thru Figure 6--6
AC 350 BT324 Figure 6--7 Thru Figure 6--13

AC 310/AC350 Thermostat One/Two Compressors Figure 6--14 To Figure 6--18

CONTROLLER FIGURE NUMBERS

(6) condenser fan motors. Figure 6--1 through
Figure 6--6shows the Thermostat with manualre--heat.
Figure 6--7 thru Figure 6--13 shows the CSDD BT324
controller usedwiththeAC310 single and dualsystems
and the AC350 single loop with transit compressors.
Figure 6--14 thru Figure 6--18 shows Thermostat
control with one or two compressors.

6--1

T--30404/08

EVAPORATOR

Compressor Clutch

Convection HeatingConnection

CONTROL PANEL

HP Switch

LP Swi tch

HEATING VALVE

Y31A

M31M

WATER PUMP HEATING

Figure 6--1 System Controls (Typical)

G

CONDENSER

R1N

R2N

VERSION B

Operation Board

S3A

S1A

VERSION A

Operation Board

S2A

S1A

AC 310 100A @ 24VDC

AC 350125A @24VDC

FOM

AC310 OPTION 150A @12VDC

ALTERNATOR

Battery 24 VDC

6--2T--304

04/08

B+

OR

11

810

1

UR

24V12V

-- --

LL

Sensors

UK

UH

BKGY

Clutch

OGRD

REF: 98- -62- -62668- -00

Y2A

V5

V4

REL 1 REL 2

Cooling Heating

WH

Inside sensor

Sensor

1 9162435

Thermostat

7

Poti.

WH

BN
WH

B1N

X20

91011

2
1

Liquid Line Valve

Y1A

or

swor

B+

RD

BKYE

U5

15A

F1A

BKBU

U2

R1N

Temperature setting

Operation Board

OEM SUPPLIED

*

Dash Control

858787a

K4A

8630

Other Signal Indicating

Vehicle Electrical System

Is Ready To Operate AC

System

OR

WHBU

WH

V1

OGRD

87

30

WHRD

86 87a

85

U3

K1A

V3

WHOG

34 5

WHYE

V2

RDWH

X3

12

WH

BKRD

Climate

S2A

High

Vent 2

1

S1A

3

7

Low

Vent 1

5A

F01A

Operation Board

T----Splice Into Freightliner

Wire 393 At Hydraulic

Wire 393

87A

86

87

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

Brake Module

*

30

A/C Power

30 A Relay

85

Battery

Evap. Low

Evap. High

Cond. Mtrs.

6--3

Breaker 10

*

5A

T--30404/08

M31M

OEM SUPPLIED

*

RD

12VDC

Ov e r -- -- R i d e S w i t c h

10A

F2A

25F

60F

=

B21F

M

Waterpump heating

Y31A

Heating valve

L P -- -- s wi t c h

P

Y8M

Compressor clutch

NOTE A

Breaker

15A

*

A/C Low Voltage

BK

60 Switch --- - Closes On Temperature Rise

25 Switch --- - Opens On Temperature Decrease

87

BK

30

87a85

86

K3A

CLR1

86

85

8787a

30

BU

Note A

BK

8

*

CR1

85

8687

30

87a

B20F

H P -- -- s wi t c h

P

B+

RD

OR

CLR2

86

85

BKGY

UK

10A 10A

F3A F4A

OGRD

87

30

87a

86

85

K2A

LL

87

30

87a

UH

*

CR2

868787a

85

30

H P -- -- s wi t c h

L P -- -- s wi t c h

P

B10F

B11F

P

Y7M

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

Compressor clutch

T----Stat

LL Solenoids

REF: 98- -62668- -00

6--4T--304

04/08

B+

U2

U4

(OPTIONAL)

REF: 98- -62668- -00

15A

15A

15A

30

8786

GN

F4M

8585

K5M

F3M

BKGN

GN

BKBU

3086

BN

85

85 87

BKOG

K6M

3086

BKWH

K4M

6

5

BN

WHGN

M3M M4M

MM

4

WHOG

Figure 6--4 Evaporator Motors 1 -- 4

M2MM1M

M

30

BK

F2M

BKYE

3086

BN

3

WHYE

86 87

K2M

15A

F1M

GN

BKBU

85 87

87

85 87

BKRD

K3M

3086

BKBU

2

BN

M

K1M

+

F01M

1

BLACK

X2

150 AMP

SAO

WHRD

+

-- --

BATTERY 12 VDC

6--5

T--30404/08

B+

U2

U5

(Optional)

K13M

8630

8587

15A

15A

15A

F6M

87a

30

F8M

85

86 87

K11M

GN

BKBU

WHOG

WHGN BU

3086

BN

85

87

85 87

K12M

3086

WHBK

K10M

15

14

1310

M

BKGN

BN

M7M M8M

M

BKOG

F7M

M6M

MM

30

GY

WHYE

87

3086

BN

12

BKYE

Figure 6--5 Evaporator Motors 5 -- 8

85

86 87

K8M

15A

F5M

B+

U2

GN

BKBU

WHRD

8587

85

K9M

3086

WHBU

K7M

11

BN

BKRD

M5M

X2

U4

REF: 98--62668--00

6--6T--304

04/08

B+

U2

BKBU

U5

BKYE

U3

OGRD

REF: 98--62668--00

(Optional)

15A

85

86

GNYE

Figure 6--6 Condenser Motors

87

30

K14M K15M

85

86

87

30

U2

B+

U5

15A

15A 15A

F13M F14M F15M F16M

GNBU

GNWH

MMM

10 13 14 15

X1

GNOG

M

WHITE

M21M M22M M23M M24M

6--7

T--30404/08

UL SWITCHES

Y7M Compressor Clutch

EVAPORATOR

Convection HeatingConnection

CONTROL PANEL

UNLOADER

HP Switch

LP Swi tch

HEATING VALVE

Y31A

M31M

WATER PUMP HEATING

CONDENSER

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

BT 324

ALT

DASH SWITCH

ALTERNATOR WITH

6--8T--304

04/08

REF: 98--62668--00

CONTROL PANEL

WP

WP -- WATER PUMP

HSV -- HEATING SOLENOID VALVE

U2 -- EVAPORATOR RELAY -- COIL

UReg -- SPEEDCONTROL POWER

U4 -- EVAPORATOR RELAY -- COIL

HSV

05G

Clutch

Compressor

05G -- 05K OPTION

(RAS)

Figure 6--8 BT324 Control Circuit (AC350)

BT324

CONTROLLER

INSIDE SENSOR

6--9

5A 5A

5A

OPTION

(ATS)

OUTSIDESENSOR

T--30404/08

U1

U2

U4

Ureg

Ureg

REF: 98--62668--00

AC310 M1M -- M4M

AC350 M1M -- M6M

INSTALLEDBLOWERS

K6M

86

M6M

87a85

X10.2

963

K5M

86

85 85

30 30

15A

F10M F11M F11M

F9M

12

X10.2

U3

U3a

K4M

86

30

87a 87 87a 87 87

K3M

86

8587a 87

CONTROL PANEL

30

15A 15A

15A

F8M

M4M M5M

F7M

F6M

X10 X10 X10

X10.2

EVAPORATOR MOTORS

M3M

F5M

Figure 6--9 BT324 Evaporator Motors (AC350)

86

30

RDBU

K2M

F4M

15A

87a 87 85

X10.1 X10.1 X10.1 X10.1 X10.1

M2M

X10 X10

X10.2 X10.2

4 7 10 13 14 11 15

86

30

K1M

87 85
87a

15A

F2M F3M

1

F1M

X2

X10.1

MMMMMM

M1M

X10

X10.2

2xRD 16

3A

Fma

BN

FOM

125A --AC350

100A --AC310

+

+

ALT

6--10T--304

04/08

+U4A

UVd

Ureg

UFri

UKo

X10.1

GY(GN)

GY(BN)

WHRD

X1

+

BU

X10

WHGN

RDBU

BUWH

CONTROL PANEL

GY(OG)

X10.2

SPEED CONTROLLERCONNECTION

2

1pol.

1

FRESH AIR FLAP

9

6

X2

7

8

X20 X21

2

1pol.

1

U4A

(OPTIONAL)

LIQUIDLINEVALVE

REF: 98--62668--00

M26M

M

15A

U2

K9M

85

15A 15A

30

87a 87 86

M25M

Figure 6--10 CSDD BT324 Condenser Motors

K8MK7M

85

87 86

30

87a

15A 15A 15A

8687a 87

85

15A

30

F13M F14M F15M F16M F17M F18M

14 15 12 11

10 13

X1

MMMM

CONDENSER BLOWER MOTORS

M

M21M M22M M23M M24M

M

U1

U4

Ureg

6--11

AC310 M21 -- M24M

AC350 M21 -- M26M

CONDENSER MOTORS

T--30404/08

Fans

8....F1M -- F12M = Individual Evaporator

Fans

9....U Reg = Evaporator Speed Regulation

10...X1 = Condenser Fans

(M1M -- M6M)

5....K7M -- K9M = Individual Condenser Fans

(M21M -- M26M)

6....Fuse = Boost Pump & Heat Valve

7....F13M -- F18M = Individual Condenser

Solenoid -- Condenser Fans

1....K1A = Compressor Clutch -- LiquidLine

2....K2A = Heat Valve -- Boost Pump

3....K3A = Evaporator Fans

4....K1M -- K6M = Individual Evaporator Fans

11...X2 = Evaporator Fans

Dash To Unit Interface Plug

12...X3 -- X4 (Not Shown On Drawing) =

+

K1M

F1M 10A

F2M 10A

K2M

F3M 10A

K3M

F4M 10A

F5M 10A

X2

F6M 10A

K4M

F7M 10A

F8M 10A

K5M

K1A

K2A

K3A

+

GND

Relay Board

K6M

K7M

F9M 10A

F10M 10A

F11M 10A

F12M 10A

F13M 15A

K8M

K9M

F14M 15A

F15M 15A

F16M 15A

F17M 15A

F18M 15A

26.38.08.001

Ureg

Part Number

Figure 6--11 AC350 With BT324 Control

K7M -- K9M

X1

--

Contact arrangement

Connect X1 -- X2

U3

U3A

Top View

SUTRAK SCHMATIC #65, 01, 28, 056--01--3

6--12T--304

K1m -- K4M K7M -- K8M

K1M -- K6M

+

RELAYS FOR EVAP.MOTORS RELAYS FOR COND. MOTORS

UNIT

AC350

AC310

04/08

1

(FROM)

(FROM)

(FROM)

05G -- 05K OPTION

LEGEND

HPS -- HIGH PRESSURE SWITCH

HSV -- HEATINGSOLENOID VALVE

LPS -- LOWPRESSURESWITCH

WP -- WATERPUMP

UPS1 -- UNLOADER PRESSURE SWITCH #1

UPS2 -- UNLOADER PRESSURE SWITCH #2

UPS3 -- UNLOADER PRESSURE SWITCH #3

UV1 -- UNLOADER VALVE #1

SUTRAC PT.#60--01--28--126

UV2 -- UNLOADER VALVE #2

SCHEMATIC 65--01--28--056-- 01--3

Figure 6--12 CSDD BT324 Control Circuit

AC--310/350 ELECTRICAL PANEL 24 V

100 Amp 24 VDC AC310

125 Amp 24 VDC AC350

X3 PLUG

X4 PLUG

6--13

T--30404/08

5A

BT--324

1

CSDD BT324

5

2

9

13

6

8

4

12

16

20

17

18

3

11

15

19

23

21

22

10

14

Reserve

24

Not Used

7

Digital Controller

All Outputs 0.5 A Max.

5A

5A

Blower Speed2

a) Blower ON

b) BlowerSpeed 1

Fresh Air

24 V(15)

Load

Relay

Valve

Blower SpeedSignal

DRM

P

>

P

Pressure

Switches

<

or 12 V

M

NTC

NTC

(Optional)

RS232 RxD

Reat

Relay

RS232 TxD

Figure 6--13 CSDD BT324

Free

Wheeling

Input Power

Ground

Night Light

Alternator

Compressor Failure Signal(Optional)

Diode

Blower Motor

Clutch

Compressor

Outside Sensor

Inside Sensor

(Optional)

OffOnOff

On

VDC

12 or 24

Off

OffOnOn

Blower Speed2 Blower Speed1

012

Speed

Blower ControlOptions a) SpeedController

(Software Selectable) b) Steps

6--14T--304

3

04/08

+

U2U4Ureg

U1

86

86

86

30

30

30

K5M K6M

K4M

87a 87 85

85

87a 87 85 87a 87

F12M

F9M F10M F11M

F8M

Ureg

3

6

9

12

15

11

X10.1 X10.1

X10

X10.1

X10.1

X10 X10

X10

X10

X10

X10.2

X10.2

X10.2

X10.2

X10.2

X10.2

M

M

MMM

M11M M12M

M10M

M7M M8M M9M

M1M -- M8M

M1M -- M12M

AC310

AC350

INSTALLED BLOWERS

14

K3M

85

86

30

10A 10A 10A 10A 10A 10A 10A 10A 10A

86

30

87a 87 85 87a 87

K1M K2M

8587a 87

86

+

30

--

BN6

F3M F4M F5M F6M F7M

F2M

10A 10A 10A

F1M

1 4 7 10 13

X2

X10.1 X10.1 X10.1 X10.1

X10 X10 X10

X10.1 X10.1 X10.1

X10

X10.1

X10

X10

FOM

X10.2

X10.2

X10.2

X10.2

X10.2

X10.2

M

M6M

EVAPORATOR MOTORS

MM

M5M

M4M

MMMM

M1M M2M M3M

+

--

24 VDC

BATTERY

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

6--15

T--30404/08

+

Grey

X10.1

+

X10

Yellow

Red

X10.2

Brown

Green

M

Installed Motors

M21M -- M24M

AC310

M21M -- M26M

AC350

MMM

+

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

MM

CONDENSER MOTORS

M

6--16T--304

04/08

23

23

U3

2

R1N

2

V6

Installed InUnits WithHeating

3

3

1

30

87a87

85

86

X3.4

3086

87a 87

85

K4A K5A

9641

F1

F2

1

7

A1P

9

1

5

HEATING

3

B1N

280P/282P

THERMOSTAT

TEMP. SENSOR

11

1

4

COOLING

2

610

K2A

86

8587a87

K6A

B1

3086

87a

8

85

X5

K3A

V7

11

B2N

2

BKYE

1

A1

4

BKRD

10

OPTION

Fresh Air Flap

YM3

RD6

U1

2

*

1

D5

V5

1

3

4

V1

V2 V4

V3

B5

347589

Operation Panels

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

6

15A

U2

F1A

X10

+

WHBU

U2

UR

WHYE

U3

GND

BN6

WHGN

U3

Ureg

87

30

87a

86

85

K1A

12

X4

D+61

Alternator

6--17

T--30404/08

2

87

30

87a

10A

F3A

31

85

86

K7A

Option

10 7 511

Compressor Unloader

OPTION

2

1

4

Unloader Valve

Y8A

B11N

+

X3.5

2

10A

3/B15

UNIT WITH 1 COMPRESSOR

F2A

X5

U3

GN

LP Switch

1

4

--

B1F

+

1

B11F

HP Switch

Y7A

4

2

+

--

Liquid Line Valve

Y7N

Compressor Clutch

21

10A

F3A

3

87

3086

87a

85

K7A

Option

10 7 5

2

LP--Switch

1

4

4

HP--Switch

1

2

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

B2F

X3.5

GN

2

B21F

Compressor Clutch

Y8M

Y7A

1

Liquid Line Valves

Y6A

UNIT WITH 2 COMPRESSORS

X20

10A

3/B15

F2A

U3

11

X5

2

LP Swi tch

1

4

B1F

+

4

HP Switch

1

2

+

B11F

Compressor Clutch

Y7M

6--18T--304

04/08

OPTION

Fresh Air Flap

1

5

VERSION B

R1

S3A

S1A

3

71

V5V1

1

2

89

5

7

(OPTION 2)

CONTROL P ANEL

34

2

Speed S etting

X4

Ventilation: Stepless

Evaporator Blowers

Clima Operation:

Stepless, depending

on temperature

OPTION

9

Fresh Air Flap

5

1

VERSION A

S3A

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

1

5

58

7

34

Clima

S2A

1

S1A

3

7

(OPTION 1)

CONTROL P ANEL

2

X4

Evaporator Blowers

Ventilation -- 2 Steps

6--19

T--30404/08

INDEX

A

Air Filters, 5--7
Apex Unit, 1--2

C

Circuit Breaker, 1--8
Clutch, 2--3
Compressor, 1--6, 1--7
Compressor Clutch Control, 2--3
Condenser Fan, 1--8
Condensing Section, 1--2
Cooling Mode, 2--2

D

DESCRIPTION, 1--1

M

Maintenance Schedule, 5--1
Manifold Gauge Set, 5--1
Modes Of Operation, 2--2

N

Noncondensibles, 5--4

O

Operating Controls, 1--7
Operating Instructions, 2--1, 3--1
OPERATION, 2--1, 3--1

P

Pre--Trip Inspection, 2--1, 3--1
Pump Down, 5--2

E

ELECTRICAL, 6--1
Evacuation, 5--3
Evaporator, 1--4, 1--6
Evaporator Fan, 1--7, 2--2
Evaporator Fan Speed Selection, 2--3

F

Filter--Drier, 5--5
Fuse, 1--8

H

Heat Valve, 5--5
Heating Cycle, 1--8
Heating Mode, 2--2
High Pressure Switch, 1--7, 1--8

R

Refrigerant Charge, 1--7, 5--2, 5--3, 5--4
Refrigerant Removal, 5--3
Refrigeration Cycle, 1--8

S

SAFETY, Safety--1
SERVICE, 5--1
Starting, 2--1, 3--1
Stopping, 2--1, 3--1
Superheat, 5--9

T

Temperature Control, 2--2
Temperature Pressure Chart, 5--10
Temperature Sensor, 1--8
Thermostatic Expansion Valve, 1--7, 5--8
TROUBLESHOOTING, 4-- 1

L

Liquid Line Solenoid, 5--6
Low Pressure Switch, 1--7, 1--8

T--304 04/08

W

Water T emperature Switch, 1--7

Index --1

A member of the United Technologies Corporation family. Stock symbol UTX
©2008 Carrier Corporation D Printed in U. S. A. 0408

Carrier Transport Air Conditioning
50 Grumbacher Road
York PA 17406 USA
Tel: [phone]
Fax: [phone]

Carrier Transicold Division,
Carrier Corporation
Transport Air Conditioning Group
P.O. Box 4805
Syracuse, N.Y. 13221 U.S A

www.carrier.transicold.com