Compressor Clutch Does Not Engage

HVAC Compressor Clutch Does Not Engage

Diagnostic Aids

The Mitsubishi scroll type A/C compressor carries an internal thermal cut off switch. The thermal cut off switch normal operation is to open and disable the compressor under extreme load and temperatures above 155°C (311°F). The internal thermal cut off switch is non-serviceable.

Test Description

Step 1 - Step 9:

Step 10 - Step 21:

Step 22 - Step 35:

Step 36 - Step 46:

The numbers below refer to the step numbers on the diagnostic table.
2. The A/C compressor relay output is disabled if engine coolant temperature is above 121°C (250°F). The engine coolant indicator will illuminate at this temperature.
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.
40. The evaporator temperature sensor is replaced as part of the evaporator core.