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

Steps 1-4:

Steps 5-14:

Steps 15-26:

Steps 27-34:

The numbers below refer to the step numbers on the diagnostic table.
2. The A/C compressor relay output is disabled it engine coolant temperature 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, bi-level 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.