1. Inspect the compressor clutch wire connector for an open or poor connection. Refer to HVAC Compressor Clutch Does Not Engage in HVAC Systems -- Manual and/or Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
2. Inspect the following fuses:

•

The A/C

•

The HTR

•

The IG

•

The DEF

•	The Blower

Did you find and correct the condition?

Go to Step 18

Go to Step 2

1. Inspect the temperature control operation.
2. Move the temperature control lever from the coldest to the hottest positions.
3. Listen for the door hitting at each end.
4. Repair as necessary.

Did you find and correct the condition?

Go to Step 18

Go to Step 3

Inspect the blower motor for proper operation. The blower motor speed should increase at each speed level as the switch is turned toward HIGH and then decrease as the switch is turned toward LOW.

Did you find and correct the condition?

Go to Step 18

Go to Step 4

Inspect for a loose, damaged, slipping or missing compressor drive belt.

Did you find and correct the condition?

Go to Step 18

Go to Step 5

Inspect the condenser fan for correct operation. Refer to Condenser Fan Inoperative .

Did you find and correct the condition?

Go to Step 18

Go to Step 6

1. Inspect the condenser for a restriction in airflow.
2. Clean and/or repair the condenser as necessary. Refer to Condenser Replacement .

Did you find and correct the condition?

Go to Step 18

Go to Step 7

1. Inspect the compressor for seizure.
2. Stop the engine.
3. Disengage the compressor clutch.
4. Rotate the compressor clutch plate, not the pulley, by hand.

Does the compressor clutch plate turn freely by hand?

Go to Step 8

Go to Air Conditioning Compressor Replacement

1. The ambient air temperature must be at least 16°C (60°F).
2. Connect the refrigerant charging station J 39500-B to the High and Low side service ports on the vehicle.
3. Both the High and Low side pressures should be almost equal to each other.

Are the High and the Low side pressures 345 kPa (50 psi) or higher?

Go to Step 9

Go to Step 13

1. Start the engine and run at idle.
2. Set the blower speed to the highest position.
3. Set the temperature control to the coldest position.
4. Set the mode control to the IP outlet position.
5. Press the A/C switch to the ON position.

Does the compressor clutch engage?

Go to Step 10

Go to HVAC Compressor Clutch Does Not Engage in HVAC Systems -- Manual

1. Monitor the compressor for any unusual knocking or loud moaning noises and/or compressor drive belt slipping.
2. Cycle the compressor clutch by pressing the A/C switch to the OFF position and back to the ON position.
3. Notice if the compressor drive belt is slipping.

Is there excessive compressor noise?

Go to Air Conditioning Compressor Replacement

Go to Step 11

1. Visually inspect the lines for a frost spot indicating a restriction.
2. Feel the lines for an abrupt temperature change. The high side components should feel warm/hot from the compressor outlet to the expansion valve.
3. The low side components should feel cool/cold from the evaporator outlet to the compressor inlet.
4. Repair as necessary.

Did you find and correct the condition?

Go to Step 18

Go to Step 12

Feel the evaporator inlet pipe (the small pipe) and the evaporator outlet pipe at the bulkhead. The evaporator inlet pipe should feel warm to the touch. The evaporator outlet pipe should feel cool to the touch.

Does the evaporator inlet pipe feel colder than the evaporator outlet pipe?

Go to Step 13

Go to Step 15

1. Leak test the refrigeration system. Refer to Leak Testing .
2. Add 0.45 kg (1 lb) of the refrigerant as necessary.
3. Evacuate and recharge the system. Refer to Refrigerant Recovery and Recharging .

Is a leak present?

Go to Step 14

Go to Step 16

Repair the leak. Refer to Leak Testing and Refrigerant Recovery and Recharging .

Is the repair complete?

Go to Step 18

--

1. Run the compressor.
2. Monitor the clutch operation and the system pressures for 5 minutes.
3. The compressor should disengage when the system pressure is outside the specified values.

High Side Pressure Range
1275-1670 kPa (185-244 psi)

Low Side Pressure Range
150-300 kPa (21-43 psi)

Does the compressor stay engaged outside the specified values?

Go to Step 17

Go to Step 16

1. Discharge the system.
2. Inspect for a restricted or malfunctioning expansion valve. Refer to Thermal Expansion Valve Replacement .

Is the repair complete?

Go to Step 18

--

Replace the A/C refrigerant pressure switch. Refer to Air Conditioning (A/C) High Pressure Switch Replacement .

Is the repair complete?

Go to Step 18

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1