Carrier GR-45 Operation manual

T--295
Bus Air
Conditioning
Equipment
Models
GR--45
GR--60
(N.A.O.)
AC Pressure Sensor

SERVICE MANUAL
OPERATION AND
Models
GR--45
GR--60
(N.A.O.)
BUS
AIR CONDITIONING
UNIT
Carrier Corporation 2000 DPrinted in U. S. A. 0300
Carrier Transicold Division, Carrier Corporation, P.O. Box 4805, Syracuse, N.Y. 13221 U. S. A.
Carrier Refrigeration Operations
AC Pressure Sensor

Safety-1 T--295
SAFETY SUMMARY
GENERAL SAFETY NOTICES
The following general safety notices supplement the specific warnings and cautions appearing elsewhere in this
manual. They are recommended precautions that must be understood and applied during operation and maintenance
of the equipment covered herein. A listing of the specific warnings and cautions appearing elsewhere in the manual
follows the general safety notices.
FIRST AID
Aninjury,nomatterhowslight,shouldnevergounattended.Alwaysobtainfirstaidormedicalattentionimmediately.
OPERATING PRECAUTIONS
Always wear safety glasses.
Keep hands, clothing and tools clear of the evaporator and condenser fans.
No work should be performed on the unit until all circuit breakers and start-stop switches are placed in the OFF
position, and power supply 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 isturned off beforeworking on motors, controllers, solenoidvalves andelectrical controls. Tag circuit
breaker and power supply to prevent accidental energizing of circuit.
Do not bypass any electrical safety devices, e.g. bridging an overload, or using any sort of jumper wires. Problems
with the system should be diagnosed, and any necessary repairs performed, by qualified service personnel.
When performingany arc welding onthe unit, disconnect all wire harness connectors from the modules in thecontrol
box. Do not remove wire harness from the modules unless you are grounded to the unit frame with a static-safe wrist
strap.
In case of electrical fire, open circuit switch and extinguish with CO2(never use water).
SPECIFIC WARNINGS AND CAUTIONS
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
FLARE NUTS AND AVOID CONTACT WITH EXPOSED SKIN OR EYES.
CAUTION
Donotunderanycircumstancesattempttoservicethemicroprocessor.shouldaproblemdevelopwith
the microprocessor, replace it.
CAUTION
If unit was recently operated, be careful of remaining hot coolant in the hoses when disassembling.
AC Pressure Sensor

iT--295
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 Apex Unit 1-2..................................................................
1.2.2 Condensing Section 1-2..........................................................
1.2.3 Evaporator Section 1-3...........................................................
1.2.4 Compressor Assembly 1-4........................................................
1.2.5 Fresh Air System 1-4............................................................
1.2.6 System Operating Controls And Components 1-4.....................................
1.3 REFRIGERATION SYSTEM COMPONENT SPECIFICATIONS 1-5........................
1.4 ELECTRICAL SPECIFICATIONS -- MOTORS 1-5......................................
1.5 ELECTRICAL SPECIFICATIONS -- SENSORS AND TRANSDUCERS 1-5..................
1.6 SAFETY DEVICES 1-5.............................................................
1.7 AIR FLOW 1-6....................................................................
1.8 AIR CONDITIONING REFRIGERATION CYCLE 1-6...................................
1.9 HEATING CYCLE 1-8.............................................................
1.10 RELAY BOARD 1-9...............................................................
1.10.1 Permanent Magnet Motors with 2 speed switching from series to parallel
connection (Option 1) 1-9........................................................
1.10.2 Electronically Communtated DC Motors with 2--speed Evaporator Input Signal (Option 2) 1-11.
1.11 LOGIC BOARD 1-12................................................................
1.12 CONTROL PANEL (Diagnostic Module) 1-13............................................
OPERATION 2-1.................................................................................
2.1 STARTING, STOPPING AND OPERATING INSTRUCTIONS 2-1..........................
2.1.1 Power to Logic Board 2-1........................................................
2.1.2 Starting 2-1....................................................................
2.1.3 Self-Test and Diagnostics (Check for Errors and/or Alarms) 2-1..........................
2.1.4 Stopping 2-1...................................................................
2.2 PRE--TRIP INSPECTION 2-1........................................................
2.3 MODES OF OPERATION 2-3.......................................................
2.3.1 Temperature Control 2-3.........................................................
2.3.2 Cooling Mode 2-3..............................................................
2.3.3 Heating Mode 2-3..............................................................
2.3.4 Boost Pump 2-3................................................................
2.3.5 Vent Mode 2-3.................................................................
2.3.6 Fresh Air System 2-3............................................................
2.3.7 Compressor Unloader Control 2-3..................................................
2.3.8 Evaporator Fan Speed Selection 2-4................................................
2.3.9 Condenser Fan Control 2-4.......................................................
2.3.10 Compressor Clutch Control 2-4....................................................

ii
T--295
TABLE OF CONTENTS (Continued)
PARAGRAPH NUMBER Page
2.3.11 Alarm Description 2-4...........................................................
2.3.12 Hour Meters 2-4................................................................
2.4 MICROPROCESSOR DIAGNOSTICS 2-4..........................................
2.4.1 Connecting 2-4.................................................................
2.4.2 Control 2-5....................................................................
2.4.3 Diagnostic Mode 2-5............................................................
2.4.4 System Parameters 2-5...........................................................
2.4.5 Test Mode 2-5.................................................................
TROUBLESHOOTING 3-1.........................................................................
3.1 SELF DIAGNOSTICS 3-1...........................................................
3.2 SYSTEM ALARMS 3-1............................................................
3.2.1 Alarm Codes 3-1...............................................................
3.2.2 Activation 3-1.................................................................
3.2.3 Alarm Queue 3-1...............................................................
3.2.4 Alarm Clear 3-1................................................................
3.3 TROUBLESHOOTING 3-1..........................................................
3.3.1 System Will Not Cool 3-4........................................................
3.3.2 System Runs But Has Insufficient Cooling 3-4........................................
3.3.3 Abnormal Pressures 3-4..........................................................
3.3.4 Abnormal Noise Or Vibrations 3-4.................................................
3.3.5 Control System Malfunction 3-5...................................................
3.3.6 No Evaporator Air Flow Or Restricted Air Flow 3-5...................................
3.3.7 Expansion Valve Malfunction 3-5..................................................
3.3.8 Heating Malfunction 3-5.........................................................
SERVICE 4-1....................................................................................
4.1 MAINTENANCE SCHEDULE 4-1....................................................
4.2 OPENING TOP COVER 4-1.........................................................
4.3 SUCTION AND DISCHARGE SERVICE VALVES 4-1...................................
4.4 INSTALLING MANIFOLD GAUGE SET 4-2...........................................
4.5 PUMPING THE SYSTEM DOWN OR REMOVING THE REFRIGERANT CHARGE 4-2.......
4.5.1 System Pump Down For Low Side Repair 4-2........................................
4.5.2 Refrigerant Removal From An Inoperative Compressor. 4-3.............................
4.5.3 Pump Down An Operable Compressor For Repair 4-3..................................
4.5.4. Removing Entire System Charge 4-4................................................
4.6 REFRIGERANT LEAK CHECK 4-4..................................................
4.7 EVACUATION AND DEHYDRATION 4-4.............................................
4.7.1 General 4-4....................................................................
4.7.2 Preparation 4-4.................................................................
4.7.3 Procedure for Evacuation and Dehydrating System 4-4.................................

iii T--295
TABLE OF CONTENTS (Continued)
PARAGRAPH NUMBER Page
4.8 ADDING REFRIGERANT TO SYSTEM 4-5...........................................
4.8.1 Checking Refrigerant Charge 4-5..................................................
4.8.2 Adding Full Charge 4-5..........................................................
4.8.3 Adding Partial Charge 4-5........................................................
4.9 CHECKING FOR NONCONDENSIBLES 4-5...........................................
4.10 CHECKING AND REPLACING HIGH PRESSURE SWITCH 4-5..........................
4.11 FILTER-DRIER 4-6................................................................
4.11.1 To Check Filter--Drier 4-6.........................................................
4.11.2 To Replace Filter--Drier 4-6.......................................................
4.12 CONDENSER COIL REPLACEMENT 4-6.............................................
4.13 EVAPORATOR COIL REPLACEMENT 4-7............................................
4.14 SERVICING THE HEAT VALVE 4-7..................................................
4.14.1 COIL REPLACEMENT 4-7......................................................
4.14.2 INTERNAL PART REPLACEMENT 4-7............................................
4.14.3 REPLACE ENTIRE VALVE 4-7...................................................
4.15 SERVICING THE LIQUID LINE SOLENOID VALVE 4-8.................................
4.15.1 Coil Replacement 4-8............................................................
4.15.2 Internal Part Replacement 4-8.....................................................
4.15.3.Replace Entire Valve 4-8.........................................................
4.16 CONDENSER FAN/MOTOR ASSEMBLY 4-8..........................................
4.16.1 Removal 4-8...................................................................
4.16.2 Inspection And Cleaning 4-9......................................................
4.16.3 Brush Replacement 4-9..........................................................
4.17 REPLACING EVAPORATOR FAN 4-9................................................
4.18 REPLACING RETURN AIR FILTERS 4-9.............................................
4.19 THERMOSTATIC EXPANSION VALVE 4-9............................................
4.19.1 Valve Replacement 4-9..........................................................
4.19.2 Superheat Measurement 4-10.......................................................
4.20 COMPRESSOR MAINTENANCE 4-10.................................................
4.20.1 Removing the Compressor 4-10....................................................
4.20.2 Transferring Compressor Clutch 4-11................................................
4.20.3 Compressor Oil Level 4-12........................................................
4.20.4 Checking Unloader Operation 4-12..................................................
4.21 TEMPERATURE SENSOR CHECKOUT 4-13...........................................
4.22 PRESSURE TRANSDUCER CHECKOUT 4-13..........................................
4.23 REPLACING SENSORS AND TRANSDUCERS 4-13.....................................
4.24 LOGIC BOARD CONFIGURATION 4-13...............................................
ELECTRICAL 5-1................................................................................
5--1 INTRODUCTION 5-1...............................................................
INDEX Index-1..................................................................................

iv
T--295
LIST OF ILLUSTRATIONS
FIGURE NUMBER Page
Figure 1-1. A/C Component Identification 1-1..................................................
Figure 1-2. Apex Unit Components 1-2........................................................
Figure 1-3. Condensing Section Components 1-3................................................
Figure 1-4. Evaporator Section Components 1-4.................................................
Figure 1-5. Air Flow Paths 1-6..............................................................
Figure 1-6. Refrigerant Flow Diagram 1-7.....................................................
Figure 1-7. Heating Cycle Flow Diagram 1-8...................................................
Figure 1-8 Relay Board (Option 1) 1-9........................................................
Figure 1-9 Relay Board (Option 2) 1-11........................................................
Figure 1-10 Logic Board 1-12................................................................
Figure 1-11. Micromate Control Panel 1-13.....................................................
Figure 2-1 Capacity Control Diagram 2-2......................................................
Figure 4-1. Opening Top Cover 4-1...........................................................
Figure 4-2.Suction or Discharge Service Valve 4-2...............................................
Figure 4-3. Manifold Gauge Set 4-2..........................................................
Figure 4-4. Low Side Pump Down Connections 4-3..............................................
Figure 4-5. Compressor Service Connections 4-3................................................
Figure 4-6. System Charge Removal Connections 4-4............................................
Figure 4-7. Checking High Pressure Switch 4-6.................................................
Figure 4-8. Filter--Drier Removal 4-6.........................................................
Figure 4-9. Heat Valve 4-7..................................................................
Figure 4-10. Liquid Line Solenoid Valve 4-8...................................................
Figure 4-11. Condenser Fan/Motor Assembly 4-8................................................
Figure 4-12. Evaporator Fan Removal 4-9.....................................................
Figure 4-13. Thermostatic Expansion Valve 4-9.................................................
Figure 4-14.Thermostatic Expansion Valve Bulb and Thermocouple 4-10..............................
Figure 4-15.Removing Bypass Piston Plug 4-11..................................................
Figure 4-16. Compressor Clutch 4-11..........................................................
Figure 4-17. Compressors 4-12...............................................................
Figure 4-18 Transducer Terminal Location 4-13..................................................
Figure 5--1. Electrical Wiring Schematic Diagram - Legend 5-2.....................................
Figure 5--2. Wiring Schematic, Permanent Magnet Motors - Interconnection 5-3.......................
Figure 5--3. Wiring Schematic, Permanent Magnet Motors - Relays to External Components 5-4..........
Figure 5--4. Wiring Schematic, Electronically Communtated Motors - Interconnection 5-5...............
Figure 5--5. Wiring Schematic, Electronically Communtated Motors - Relays To External Components 5-6..

vT--295
LIST OF TABLES
TABLE NUMBER Page
Table 2-1. Evaporator Fan Speed Relay Operation 2-4.............................................
Table 2-2. Controller Test List 2-5.............................................................
Table 2-3. Parameter Codes 2-6...............................................................
Table 3-2 Alarm Codes 3-2..................................................................
Table 3-3 General System Troubleshooting Procedures 3-4.........................................
Table 4-1. Temperature Sensor Resistance 4-13...................................................
Table 4-2. PressureTransducer Voltage 4-14......................................................
Table 4-3. Logic Board Configuration 4-14.......................................................

1-1 T--295
SECTION 1
DESCRIPTION
1.1 INTRODUCTION
This manual contains Operating Instructions, Service
Instructions and Electrical Data for the Model GR Air
Conditioning and Heating equipment furnished by
Carrier Transicold Division as shown in Table 1-1.
ModelGRsystemsconsistsofanApexUnit,containing
the condenser and evaporator and an engine
compartment mounted compressor. To complete the
system, the air conditioning and heating equipment
interfaces with electrical cabling, refrigerant piping,
enginecoolant piping (forheating), ductworkandother
components furnished by the bus manufacturer.
Operation of the units is controlled automatically by a
microprocessor based Micromax Controller which
maintains the vehicle’s interior temperature at the
desired set point.
Table 1-1. Model
MODEL SERIES COMPRESSOR CONDENSER
FANS EVAPORATOR FANS
GR45 ROOF MOUNTED 05K 4 4
GR60 ROOF MOUNTED 05G 6 6
Table 1-2. Additional Support Manuals
MANUAL/FORM NUMBER EQUIPMENT COVERED TYPE OF MANUAL
62--02491 O5K Compressor Operation and Service
62--02460 O5K Compressor Parts List
62--02756 O5G Compressor Operation and Service
T--200 O5G Compressor Parts List
1
3
68
2
4
5
12 10 9
7
11
13
1. Compressor
2. Refrigerant Lines
3. Compressor Harness
4. Heat Valve
5. Electronics Boards
6. Apex Unit
7. Main Harness
8. Driver Control
9. Power Harness
10. Power Relay
11. Battery
12. Alternator
13. Discharge Check Valve
Figure 1-1. A/C Component Identification

1-2
T--295
1.2 GENERAL DESCRIPTION
1.2.1 Apex Unit
The apex unit (see Figure 1-2) includes the condensing
section, evaporator section, Micromax electronics, and
the Fresh Air System. All components are accessible by
lifting the top cover. Descriptions of the systems are
provided in the following sub paragraphs.
1
2
3
4
5
6
7
8
10
11
9
1. Top Cover
2. Gas Spring (2)
3. Condenser Section (See Figure 1-3)
4. Evaporator Section (See Figure 1-4)
5. Base
6. Fresh Air System
7. Gas Spring Support (2)
8. Lock (2)
9. Serial Plate
10. Hinge
11. Condenser Fan Grille (4-GR45,
6-GR60)
12. Front Drain (2)*
13. Intermediate Drain (2)*
14. Evaporator Rear Drain (2)*
15. Condenser Rear Drain (2)*
* Not Shown
Figure 1-2. Apex Unit Components
(GR-60 Shown)
1.2.2 Condensing Section
The condensing section (Figure 1-3) includes the
condenser coils, fan and motor assemblies, filter-drier,
receiver, liquid line solenoid valve, service valves, and
an ambient temperature sensor.
The condenser coils provide heat transfer surface for
condensing refrigerant gas at a high temperature and
pressure into a liquid at high temperature and pressure.
The condenser fans circulate ambient air across the
outside of the condenser tubes at a temperature lower
than refrigerant circulating inside the tubes; 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.

1-3 T--295
The receiver collects and stores liquid refrigerant. The
receiver is fitted with upper and lower liquid level sight
glasses to enable determining refrigerant liquid level.
The receiver is also fitted with a fusible plug which
protects the system from unsafe high pressure
conditions. The liquid line solenoid valve closes when
system is shut down to prevent flooding of coils with
liquid refrigerant. The servicevalvesenableisolationof
the filter-drier for service. The ambient temperature
sensor measures ambient temperature and sends an
electrical signal to the controller.
The discharge check valve is a spring loaded, normally
closedvalvethatopenswiththeflowofrefrigerantfrom
the compressor. When the compressor clutch is
disengaged, the discharge check valve will close,
preventing the flow of high pressure liquid from the
condenser back into the compressor.
12 3 45
6
7
8
9
10
11
12
13
1. Condenser Coil (2)
2. Receiver
3. Protection Plate
4. Service Valve
5. Discharge Line
6. Precharge Valve
7. Liquid Line Solenoid Valve
8. Filter Drier Upper Support
9. Filter Drier
10. Filter Drier Lower Support
11 Condenser Fan and Motor Assembly
(4-GR45, 6-GR60)
12. Condenser Coil Fastener (4)
13. Condenser Motor Support
(4-GR45, 6-GR60)
Figure 1-3. Condensing Section Components
(GR-60 Shown)
1.2.3 Evaporator Section
The evaporator section (Figure 1-4) includes the
evaporator coils, six fan and motor assemblies,
evaporator/heater coil assemblies, a thermostatic
expansion valve and condensate drain connections.
The evaporator coils provide heat transfer surface for
transferring heat from air circulating over the outside
the coil to refrigerant circulating inside the tubes; thus
providing cooling. The heating coils provide 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 over the
coils. The air filters remove dirt particles from the air
before it passes over the coils. The thermostatic
expansion valve meters flow of refrigerant entering the
evaporator coils. The heat valve controls the flow of
engine coolant water to the heating coils upon receipt of
a signal from the controller. The condensate drain
connections provide a means for connecting tubing for
disposing of condensate collected on the evaporator
coils during cooling operation.

1-4
T--295
123 4 5
6
7
8
9
1. Evaporator Coil With Integrated
Heating Coil (2)
2. Protection Plate
3. Expansion Valve
4. Evaporator Motor Fastening Clamps
(4-GR45, 6-GR60)
5. Evaporator Motor (4-GR45,
6-GR60)
6. Suction Line
7. Heating Lines
8. Service Valve
9. Evaporator Harness
Figure 1-4. Evaporator Section Components
(GR-60 Shown)
1.2.4 Compressor Assembly
The compressor assembly includes the refrigerant
compressor, clutch assembly, suction and discharge
service valves, high pressure switch, low pressure
switch, suctionand dischargeservicing (charging)ports
and electric solenoid unloaders.
The compressor raises the pressure and temperature of
the refrigerant and forces it into the condenser tubes.
The clutch assembly provides a means of belt driving
the compressor by the bus engine. The suction and
discharge service valves enable servicing of the
compressor. Suction and discharge servicing (charging)
ports mounted on the service valves enable connection
of charging hoses for servicing of the compressor, as
well as other parts of the refrigerant circuit. The high
pressure switch contacts open on a pressure rise to shut
down the system when abnormally high refrigerant
pressures occur. The electric unloaders provide ameans
of controlling compressor capacity, which enables
control of temperature insidethe bus. For more detailed
information on the compressor, refer to manual number
62-02756.
1.2.5 Fresh Air System
The Fresh Air System (6, Figure 1-2) consists of a
damper and damperoperator. The damper operator may
becontrolled bythe driver,if aswitchis provided. Inthe
automatic mode, it is controlled by the Micromax to
open and close the damper to allow addition of fresh air
into the air entering the evaporator coil. For additional
information on air flow, refer to paragraph 1.7.
1.2.6 System Operating Controls And Compo-
nents
The system is operated by a Carrier Transicold
Micromax microprocessorcontroller which consist of a
logic board (Figure 1-10), relay board (Figure 1-8 or
Figure 1-9), andmanual operatorswitches. Themanual
operatingswitchesarelocatedonthedriverscontroland
may consist of a single OEM supplied ON/OFF switch,
additional OEM supplied switches or a Carrier
Transicold supplied Micromate control panel
(Figure 1-11). The logic board 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 include
Cooling, Heat and Vent. On systems fitted with only an
ON/OFF switchand on systems with the Micromateset
in the AUTO mode, the logic board will cycle the
system between the operating modes as required to
maintain desired set point temperature.
In the vent mode the evaporator fans are operated to
circulate air in the bus interior.
Intheheatmodetheheatvalveisopenedtoallowaflow
of engine coolant through the heat section of the
evaporatorcoil. The evaporator fans operateto circulate
air over the evaporator coil in the same manner as the
vent mode.

1-5 T--295
In the cooling mode the compressor is energized while
the evaporator and condenser fans are operated to
provide refrigeration as required. The compressor is
fitted with cylinder unloaders to match compressor
capacity to the bus requirements. Once interior
temperature reaches the desired set point, the system
may operate in the clutch cycle or reheat mode. A
controller programmed for clutch cycle will
de--energizethecompressorclutchandallowthesystem
to operate in the vent mode until further cooling is
required. A controller programmed for reheat will
maintain compressor operation and open the heat valve
to allow reheating of the return air. In the reheat mode
interior temperature is maintained at the desired set
point while additional dehumidification takes place.
Controls may also be provided to allow manual
operation of the evaporator fans in low or high speed
andmanualcontrolofthefreshairdamperintheopenor
closed position.
1.3 REFRIGERATION SYSTEM COMPONENT
SPECIFICATIONS
a. Refrigerant Charge
R--134a 14.3 lb (6.5 kg)
b. Compressor
UNIT MODEL GR45 GR60
Compressor 05K 05G
No of Cylinders 4 6
Weight - Dry 108 lbs
(49 kg) 137 lbs (62 kg)
Oil Charge 5.5 pints
(2.6 liters) 6.75 pints (3.2 liters)
Oil Level:
Levelinsightglass betweenMin.--Maxmarkson
compressor crankcase (curbside)
Approved Compressor Oils - R-134a:
Castrol: Icematic SW68C
Mobil: EAL Arctic 68
ICI: Emkarate RL68H
c. Thermostatic Expansion Valve:
Superheat Setting (Non-externally adjustable):
10 to 12F
MOP Setting (Nonadjustable): 55 ±4 psig (3.74
±2.27 bar)
d. High Pressure Switch (HPS):
Opens at: 300 ±10 psig (20.41 ±0.68bar)
Closes at: 200 ±10 psig (13.61 ±0.68bar)
e. Low Pressure Switch (LPS)
Opens at: 6 ±3psig (0.41 ±0.20 bar)
Closes at: 25 ±3psig(1.7±0.20 bar)
1.4 ELECTRICAL SPECIFICATIONS -- MOTORS
a. Evaporator Fan Motor
Evaporator Motor ECDC* Permanent
Magnet
p
27.5
VDC 24 VDC 12 VDC
Horsepower (kW) 0.34(.25) 1/8 (.09)
Full Load Amps
(FLA) 8.4 9.5 19
Operating Speed
High/Low (RPM) 4252/ 3165 4200/ 1850
Bearing Lubrication Factory Lubricated (addi-
tional grease not required)
b. Condenser Fan Motor
Condenser Motor ECDC* Permanent
Magnet
24 VDC 24 VDC 12 VDC
Horsepower (kW) 0.15(.11) 1/8 (.09)
Full Load Amps
(FLA) 7 9 18
Operating Speed
High/Low (RPM) 4252/ NA 4200/ 1850
Bearing Lubrication Factory Lubricated (addi-
tional grease not required)
* Electronically Communicated Direct Current
1.5 ELECTRICAL SPECIFICATIONS -- SENSORS
AND TRANSDUCERS
a. Suction and Discharge Pressure Transducer
Supply Voltage: 4.5 to 5.5 vdc (5 vdc nominal)
Supply current: 8 mA maximum
Output Range: 8K ohms minimum
Input Range: --6.7 to 450 psig (--0.46 to 30.62 bar)
Output Current: -1.5 mA minimum to
1.5 mA maximum
Output Voltage: vdc = 0.0098 x psig + 0.4659
(See Table 4-2 for calculations.)
b. Temperature Sensors
Input Range: --52.6 to 158F (--47 to 70C)
Output: NTC 10K ohms at 77F(25C)
(See Table 4-1 for calculations.)
1.6 SAFETY DEVICES
System components are protected from damage caused
by unsafe operating conditions with safety devices.
Safety devices with Carrier Transicold supplied
equipment include high pressure switch (HPS), low
pressure switch (LPS), circuit breakers and fuses.
a. Pressure Switches
High Pressure Switch (HPS)
During the A/C mode, compressor operation will
automatically stop if the HPS switch contacts open due
toanunsafeoperatingcondition.OpeningHPScontacts
de-energizes, through the controller, the compressor
clutchshutting down thecompressor. Thehigh pressure
switch (HPS) is installed in the center head of the
compressor.

1-6
T--295
Low Pressure Switch (LPS)
The low pressure switch is installed in the compressor
and opens on a pressure drop to shut down the system
whena low pressurecondition occurs. Inaddition, ifthe
control monitors a pressure less than 10 psig (0.68
bar)by the suction pressure transducer mounted in the
evaporator section, the system will be shut down for at
least one minute.
b. Fuses and Circuit Breakers
The Relay Board is protected against high current by an
OEM supplied 150 amp fuse. Independent 15 amp
circuit breakers protect each motor while the output
circuits are protected by an additional 15 amp circuit
breaker. During ahigh current condition, thebreaker (or
OEM fuse) may open. When power is removed from a
device, a breaker alarm will be generated.
c. Ambient Lockout
The ambient temperature sensor located in the
condenser section measures the condenser inlet air
temperature. When the temperature is below the cut out
set point the compressor is locked out until the
temperature rises above thecut in setting. The setpoints
maybeprogrammedtocutoutat45F7.2C)andcutin
at 50F10C) or cut out at 25 F--3.9C) and cut in at
45F7.2C) in accordance with bus purchase
specification. This setting protects the compressor from
damage caused by operation at low pressures.
1.7 AIR FLOW
The paths for ambient air through the condenser and
coach air through the evaporator are illustrated in
Figure 1-5.
1.8 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).
The main components of the system are the
reciprocating 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 condensertubes.
The condenser fan circulates surrounding air (which is
at a temperature lower than the refrigerant) over the
outside of the condenser tubes. Heat transfer is
established from the refrigerant (inside the tubes) to the
condenser air (flowing over the tubes). The condenser
tubes have fins designed to improve the transfer ofheat
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 receiver serves as a liquid refrigerant reservoir so
that a constant supply of liquid is available to the
evaporators as needed, and acts as a storage space when
pumping down the system. The receiver is equipped
with sight glasses to observe the refrigerant for
restricted flow and correct charge level.
The refrigerant leaves the receiver and passes through
the receiver outlet/service valve, through a filter-drier
where an absorbent keeps the refrigerant clean and dry.
From the filter-drier, the liquid refrigerant then flows
through the liquid line solenoid valve to the
thermostatic expansion valve. the thermal expansion
valve reducepressure and temperature of the liquidand
meters the flow of liquid refrigerant to the evaporator to
obtain maximum use of the evaporator heat transfer
surface.
Thelowpressure,lowtemperatureliquidthatflowsinto
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
evaporatorair(flowingoverthe 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 low temperature
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.
2. FROM COACH
3. THROUGH EVAPORATOR
4. THROUGH FAN
5. RETURN TO COACH
1. FROM AMBIENT
2. THROUGH CONDENSER
3. THROUGH FAN 4. RETURN TO AMBIENT
1. FROM DAMPER
(IF ACTIVE)
CONDENSER AIR FLOW
EVAPORATOR
AIR
FLOW
Figure 1-5. Air Flow Paths

1-7 T--295
COMPRESSOR
DISCHARGE
SUCTION
MAIN ENGINE
RADIATOR
DISCHARGE
LIQUID
SUCTION
A
A
VIEW A-A
RECEIVER
12 345 6
7
8
9
10
11
11
12
13
14
15
16
16
17
18
1. Condenser Fan Assembly
2. Evaporator Fan Assembly
3. Expansion Valve
4. Expansion Valve Equalizer Line
5. Liquid Line
6. Precharge Valve
7. Expansion Valve Bulb
8. Pressure Transducer, Low Side
9. Service Port, Low Side
10. Pressure Transducer, High Side
11. Service Valve With Port
12. Liquid Line Solenoid Valve
13. Filter Drier
14. Service Port, High Side
15. Discharge Check Valve
16. Receiver
17. Refrigerant Sight Glass
18. Moisture Indicator
Figure 1-6. Refrigerant Flow Diagram
(GR60 Shown)

1-8
T--295
COMPRESSOR
MAIN ENGINE
RADIATOR
SUPPLY
RETURN
HEAT
VALVE
BOOST
PUMP
Figure 1-7. Heating Cycle Flow Diagram
(GR60 Shown)
1.9 HEATING CYCLE
Heating circuit (Figure 1-7) components furnished by
Carrier Transicold include the integral evaporator coil
heater cores and a solenoid operated heat valve.
Componentsfurnishedby the bus manufacturerinclude
auxiliary heater and boost water pump. The controller
automatically controls the heat valveduring theheating
and reheat modes to maintain required temperatures
inside the bus. Engine coolant (glycol solution) is
circulated through the heating circuit by the engineand
an auxiliary boost water pump. When the heat valve
solenoid is energized, the valve will open to allow
enginecoolanttoflowthroughtheheatercoil.Thevalve
is normally closed so that if a failure occurs, the system
will be able to cool.

1-9 T--295
1.10 RELAY BOARD
1.10.1 Permanent Magnet Motors with 2 speed switching from series to parallel connection (Option 1)
JP2
D2 D6 CB 4
K2 CB 3
CB 2
K1 CB 1
CB 6
EF4EF3 EF6
D14
EF2
K5
EF1
D17
K4
EF5 CF3
D26 D30 CB 10
CB 8
CB 9
CF1
CB 5
K3 CB 7
K20K18
K22K24
CF4
K23K21
CF6 CF5
D38 D41
CF2
K11 K10 K12 D85
JP1
K13K19
JP3 JP4
K9
CB 11
CB 12
CB 13
JP6
K15K14
K17K16
JP5
D60
D66
D69
D51
D72
D57
D63
K8
K7
K6
D54
23
45
1
23
1
23
45 6
1
2
34
1
Figure 1-8 Relay Board (Option 1)
a. Relays
K1 Energizes evaporator fans 1 & 2 in high speed
or evaporator fans 1,2,3 & 4 in low speed.
K2 Energizes evaporator fans 3 & 4 in high speed
(not energized in low speed).
K3 Energizes evaporator fan 5 in high speed or
evaporator fans 5 & 6 in low speed.
K4 Energizes evaporator fan 6 in high speed (not
energized in low speed).
K5 Connects the negative side of evaporator fans
1 & 2 to ground in high speed. Connects the
negative side of evaporator fans 1 & 2 to
positive side of evaporator fans 3 & 4 in
low speed
K6 Connects the negative side of evaporator fan
5 to ground in high speed. Connects the
negative side of evaporator fan 5 to
positive side of evaporator fan 6 in
low speed
K 7 Energizes condenser fans 1 & 2 in high speed
or condenser fans 1,2,3 & 4 in low speed
K 8 Energizes condenser fans 3 & 4 in high speed
(not energized in low speed).
K 9 Energizes condenser fan 5 in high speed or
condenser fans 5 & 6 in low speed.
K10 Energizes condenser fan 6 in high speed
(not energized in low speed).
K11 Connects the negative side of condenser fans
1 & 2 to ground in high speed. Connects the
negative side of condenser fans 1 & 2 to
the positive side of condenser fans 3 & 4 in
low speed.
K12 Connects the negative side of condenser fan
5 to ground in high speed. Connects the
negative side of condenser fan 5 to
the positive side of condenser fan 6 in
low speed.
K13 Energizes the A/C clutch.
K14 Energizes unloader 1.
K15 Energizes unloader 2.
K16 Energizes the fresh air damper.
K17 Energizes the heat valve.
K18 Energizes the fault light output.
K19 Energizes the Boost Pump.
K20 Energizes the spare output.
K21 Is energized by the logic board to turn the
evaporator fans on high. The contacts of this
relay energize the coils of relays K1, K2,
K3 & K4.
K22 Is energized by the logic board to turn the
evaporator fans on low. The contacts of this
relay energize the coils of relays K1, K3,
K5 & K6.
K23 Is energized by the logic board to turn the
condenser fans on high. The contacts of this
relay energize the coils of relays K7, K8,
K9 & K10.
K24 Is energized by the logic board to turn the
condenser fans on low. The contacts of this
relay energize the coils of relays K7, K9,
K11 & K12.

1-10
T--295
b. Thermal Circuit Breakers
CB 1 Evaporator Fan #1. 15 Amp.
CB 2 Evaporator Fan #2. 15 Amp.
CB 3 Evaporator Fan #3. 15 Amp.
CB 4 Evaporator Fan #4. 15 Amp.
CB 5 Evaporator Fan #5. 15 Amp.
CB 6 Evaporator Fan #6. 15 Amp.
CB 7 Condenser Fan #1. 15 Amp.
CB 8 Condenser Fan #2. 15 Amp.
CB 9 Condenser Fan #3. 15 Amp.
CB10 Condenser Fan #4. 15 Amp.
CB11 Condenser Fan #5. 15 Amp.
CB12 Condenser Fan #6. 15 Amp.
CB13 A/C clutch, Unloaders 1&2,
Fresh Air Damper, Heat Valve,
Fault Output and Spare
output. 15 Amp
c. Connectors
EF1-EF6 Evaporator fans.
CF1-CF4 Condenser fans.
JP1 External evaporator & condenser fan
thermal overload connections.
JP2 Logic board connector.
JP3 Boost pump.
JP4 A/C clutch, fault output, compressor high
pressure switch.
JP5 Spare output, fresh air output, heat valve.
JP6 Unloaders 1 & 2.
d. LEDS
D 2 Relay K1 output active (evaporator fans 1,2,3 &
4 energized)
D 6 Will be brightly lit if evaporator fans 1, 2, 3 & 4
are on high. Will be at half intensity of they are on low.
D14 Relay K3 output active (evaporator fans 5 & 6
energized).
D17 .Will be brightly lit if evaporator fans 5 &6 are
on high. Will be at half intensity of they are on low.
D26 Relay K7 output active (condenser fans 1, 2, 3
& 4 energized).
D30 Will be brightly lit if condenser fans 1, 2, 3 & 4
are on high. Will be at half intensity of they are on low.
D38 Relay K9 output active (condenser fans 5 & 6
energized).
D41 Will be brightly lit if condenser fans 5 &6 are on
high. Will be at half intensity of they are on low.
D51 A/C clutch output active.
D54 Unloader 1 output active.
D57 Unloader 2 output active.
D60 Fresh air output active.
D63 Heat valve output active.
D66 Fault output active.
D69 Boost pump output active.
D72 Spare output active.

1-11 T--295
1.10.2 Electronically Communtated DC Motors with 2--speed Evaporator Input Signal (Option 2)
D30
D2 D6
K2
K1
D26
D17D14
EF3
CB 4
EF4
EF HIGH SIGNAL
EF6 EF5
K3
K4
CB 3
CB 2
EF1
CB 1
EF2
K5
D81
CB 6
CB 5
K8
K7
K18
K20
K14
K16
D41D38
K22
CF3
CB 10
K24
CF4
CF HIGH SIGNAL
K23K21
CF6 CF5
K9
K10
CF1
CB 8
CB 9
CB 7
CF2
K11
CB 13
D85
CB 11
CB 12
D51
D69
JP1
JP2
D66
D72
D63
D60
D57
K19
K13
K17
K15 D54
JP3 JP4 JP6
JP5
23
45
1
23
1
23
45 6
1
2
34
1
Figure 1-9 Relay Board (Option 2)
a Relays
K1 Energizes evaporator fans 1 & 2
K2 Energizes evaporator fans 3 & 4.
K3 Energizes evaporator fan 5.
K4 Energizes evaporator fan 6.
K5 Provides evaporator fan high output signal.
(Motors are in low speed when K5
is de--energized)
K6 Not Used
K 7 Energizes condenser fans 1 & 2.
K 8 Energizes condenser fans 3 & 4.
K 9 Energizes condenser fan 5
K10 Energizes condenser fan 6.
K13 Energizes the A/C clutch.
K14 Energizes unloader 1.
K15 Energizes unloader 2.
K16 Energizes the fresh air damper.
K17 Energizes the heat .
K18 Energizes the fault light output.
K19 Energizes the Boost Pump.
K20 Energizes the spare output.
K21 or K22 Is energized by the logic board to
turn the evaporator fans on. The contacts
of these relays energize the coils of relays K1,
K2, K3 & K4.
K23 or K24 Is energized by the logic board to
turn the condenser fans on high. The contacts
of these relays energize the coils of relays K7,
K8, K9 & K10.
b Thermal Circuit Breakers
Refer to paragraph 1.10.1b.
c. Connectors
Refer to paragraph 1.10.1c.
EF HIGH SIGNAL Output to the evaporator fans
to operate on high.
CF HIGH SIGNAL Output to the condenser fans
to operate on high.
d. LEDS
Refer to paragraph 1.10.1d.
D81 Evaporator fans on high
D85 Condenser fans on high

1-12
T--295
1.11 LOGIC BOARD
J1 Logic board power in.
J2 Display interface.
J3 Manual control inputs.
J4 Interlock Inputs
(WTS, low side pressure switch etc.)
J5 Relay board interface.
J6 Sensor inputs (Thermistors, etc.).
J7 Diagnostics interface (RS232, DB9).
D2 Blinks once per second in normal operation.
On steady to indicate alarms detected.
D3 Off In normal operation, blinks out alarm
codes (2 digits each) when alarms detected.
A-P Configuration Jumpers
Figure 1-10 Logic Board