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 8:

Step 9 - Step 21:

Step 22 - Step 34:

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 (ECT) is above 121°C (250°F). The engine coolant indicator will illuminate at this temperature.
3. Pressing the center of the left side driver temperature control switch and setting the air temperature control switch in a cold setting activates A/C operation. For the purpose of this and future steps where A/C operation is necessary, believe mode is used for consistent testing.
6. The HVAC control module is inoperative when the module does not respond to any operator control requests to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.