Challenger Terra Gator 3244 Chassis. Manual - part 112

627333-A  

5-41

HVAC Testing and Adjusting

TROUBLESHOOTING AIR CONDITIONER 
CONTROL

Problem List

Problems listed below are discussed in more detail.

•

No  display

•

No blower fan

•

No heat

•

No cooling

•

System is putting out hot air when cooling is

needed.

•

No HVAC system function

•

No fan or erratic fan

•

Electric actuator for airflow is not moving or working

properly.

Probable Causes

The following offers problems and a probable solution: 

No Display

1. Turn control panel on with mode switch.

2. Check display for illumination.

3. Verify control panel is connected properly.

4. Check connection of wire harness to unit.

5. Verify control panel is receiving 12 volts of power.

6. Verify control panel is properly grounded.

Probable Solution

1. Replace control panel.

No Blower Fan

1. Turn blower fan to high.

2. Ensure blower fan is connected properly.

3. Verify circuit breakers and fuses are in tact.

4. Verify HVAC unit is receiving 12 volts of power.

5. Verify blower motor is receiving 12 volts of power.

6. Verify blower motor is properly grounded.

Probable solution

1. Replace fuse or circuit breaker.

2. Replace blower motor.

3. Replace electronic control module.

No Heat

1. Turn up heat with control button.

2. Verify warm coolant is flowing into heater core by

testing heater hoses.

3. Verify water valve is working correctly.

4. Inspect water valve for jammed components.

Probable Solution

1. Replace water valve.

No Cooling

1. Turn down heat with control button.

2. Turn mode switch to enable defrost.

3. Verify refrigerant compressor has voltage at clutch.

4. Verify circuit breakers and/or fuses are intact.

5. Verify relay for clutch on wire harness has voltage.

6. Verify system is fully charged with refrigerant.

7. Verify heater valve is closed

Probable Solution

1. Inspect relay for clutch. If necessary, replace relay.

2. Replace heater valve.

System is putting out cool air when heat needed

1. Verify temperature sensor for cab airflow is

connected correctly.

2. Verify water valve is working properly. refer to No

Heat for additional information.

Probable Solutions

1. Replace temperature sensor for cab airflow.

2. Replace control module.

System is putting out hot air when cooling 

needed.

1. Verify temperature sensor for cab airflow is

connected correctly.

2. Verify water valve is working properly and water

valve is not stuck open.

3. Verify compressor clutch is working properly, refer to

No Cooling for additional information.

Probable Solution

1. Replace temperature sensor for cab airflow.

2. Replace control module.

No Fan or Erratic Fan

1. Set rotary control for blower fan to maximum.

2. Ensure blower fan is connected properly.

3. Verify circuit breakers or fuses are intact.

4. Verify HVAC unit as 12 volts of power.

5. Verify blower motor has 12 volts when rotary control

is at maximum.

Probable Solutions

1. Replace blower motor.

2. Replace control module.

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627333-A  

HVAC Testing and Adjusting

Nothing Works

None of the following components work:

•

Fan

•

Compressor clutch

•

Water control valve

1. Check for error code 17.

See Systems Operation/Testing And Adjusting,

Troubleshooting Faults With Service Codes for

information on checking error codes.

2. Verify control module is receiving 12 volts of power.

NOTE: Use a voltmeter to check voltage. This can be

verified by disconnecting and connecting DT

connector (four pin) on control module. A faint

click in module indicates electrical power is

energizing an internal relay.

3. Verify serial communication ports are not damaged.

4. Verify control panel is connected properly.

5. Verify wire harness is connected to unit properly.

6. Verify pin 17 and 18 are connected securely into DT

connector (40 pin) on control module and are

making good contact.

Probable Solution

1. Replace control module.

Electric Actuator for Mode of Airflow is not 

Moving or Working Properly

1. Verify control module is receiving electrical power.

2. Verify there are no error codes.

3. Verify component for electric actuator is not

jammed.

4. Inspect wire harness and connections.

Probable Solutions

1. Replace electric actuator for mode of airflow.

627333-A  

5-43

HVAC Testing and Adjusting

REFRIGERANT COMPRESSOR OIL - 
CHECK

General

A special refrigerant oil is used in the air conditioning

system, the oil mixes completely with refrigerant so all

components receive lubrication. A check of the

refrigerant oil in the compressor will give an indication

of the amount of oil in the system.

NOTE: Generally, when there is a major loss of oil,

check compressor oil. 

Following is a list of other causes for oil loss: 

•

Broken refrigerant hose

•

Hose fitting (leaks)

•

Badly leaking compressor seal

•

Component damage

Complete Check of Compressor Oil

When replacement of a component is necessary, follow

the procedure below to determine amount of refrigerant

oil (lost oil) needed in compressor.

FIG. 1: Compressor Components

(1)

Pulley

(2)

Hose (Low Pressure)

(3)

Hose (High Pressure)

(4)

Electrical Harness

(5)

Service Valve (Low Pressure)

(6)

Service Valve (High Pressure)

(7)

Plug (Oil Change)

(8)

Belt (Engine Driven Component)

1. Operate engine at 1000 rpm and set temperature

on maximum cooling. Move fan speed switch to

HIGH, system will stabilize in a minimum of ten

minutes.

2. Stop engine and remove refrigerant charge from

system. Install a plug in all open lines, refer to

Testing and Adjusting, Refrigerant Recovery. 

3. Remove compressor from machine and place

protective caps on all fittings and hoses.

4. Place compressor in a horizontal position so oil

plug is facing down. Remove oil plug from

compressor and drain oil into a clean container.

Rock compressor back and forth to remove all oil

and rotate compressor shaft to drain oil from sump.

Inspect oil for contaminants, metal chips, rubber

particles, or any other foreign material. Dispose of

oil in a suitable container. Use the following list as a

guide for adding oil to compressor.

•

If the amount of oil drained from compressor is

177 mL (6 fl oz) to 237 mL (8 fl oz), replace the

same amount. Never add more than 237 mL

(8 fl oz) of refrigerant oil.

FIG. 1

g00296421

1

3

2

4

5

6

7

8

HVAC Testing and Adjusting

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627333-A  

•

If the amount of oil drained from compressor is

less than 177 mL (6 fl oz), add 177 mL (6 fl oz)

to 237 mL (8 fl oz) of new refrigerant oil.

If too much oil is added to system and a total of

more than 325 mL (11 fl oz) of oil is in system,

cooling capacity will be reduced. If too little oil has

been added to system, compressor may fail due to

a lack of lubrication.

If particles of metal or other foreign material are

present in system, flush system, refer to Testing

and Adjusting, Refrigerant System - Flush. Refer to

Testing and Adjusting, Air Conditioning System

Troubleshooting.

•

Add oil to compressor through opening for oil

plug or inject oil through ports for charging.

Compressor must be positioned so refrigerant

oil does not flow out of service valves. Do not

rest compressor on compressor shaft. Turn

compressor shaft by hand when compressor is

filled. Oil will slowly flow into compressor. Only

use refrigerant oil approved and

recommended.

•

Add oil to any components being installed.

•

Inject oil into system through ports for low

pressure charging.

5. After correct amount of refrigerant oil has been

added, install compressor and drive belt, refer to

Testing and Adjusting, Refrigerant System -

Charge.

REFRIGERANT SYSTEM - CHARGE

Relationship Between Temperature and 
Pressure (R-134a Refrigerant)

Use table to determine pressure and contamination

level of a refrigerant container. Table can also be used

for an air conditioning system that is not operating. The

system must not operate for 10 to 12 hours and must

not be stored in direct sunlight to stabilize ambient

temperature.

If pressure measured at any specific temperature does

not match pressure given on chart, the following may

exist:

•

Contaminants in system

•

Incorrect refrigerant