Compressor Clutch Does Not Engage

HVAC COMPRESSOR CLUTCH DOES NOT ENGAGE

DIAGNOSTIC AIDS
The refrigerant temperature at the temperature sensor in the thermal expansion valve (TXV) controls cycling of the compressor clutch to prevent freezing of the evaporator core. The compressor is disabled when the temperature goes below 3 °C (37 °F) and vehicle speed is greater than 5 mph (8 km/h). The compressor is enabled when the temperature exceeds 4 °C (40 °F). The minimum cycling time OFF is 4 seconds. Refer to Air Temperature Description and Operation for a voltage temperature value table of the evaporator temperature sensor.

TEST DESCRIPTION

Steps 1 - 7:

Steps 8 - 17:

Steps 18 - 28:

Steps 29 - 43:

The numbers below refer to the step numbers on the diagnostic table.
2. The air conditioning (A/C) compressor relay output is disabled if the engine coolant temperature is above 96 °C (205 °F).
3. Place the mode switch in any position except OFF, and place the air temperature control switch in a cold setting. Use the bi-level mode for consistent testing of the A/C system operation.
6. The HVAC control module is inoperative if the module does not respond to any operator control requests.
23. The compressor is disabled when the evaporator temperature goes below 3 °C (38 °F)
34. Check the connection by removing and securely reinstalling before replacement of the HVAC control is considered.