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 1-2:

Step 3-4:

Step 5-9:

Step 10-14:

Step 15-19:

Step 20-27:

Step 28-34:

Step 35-41:

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. Placing the mode switch in any position other than OFF, along with placing 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 assembly 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.
14. An audible relay click will be heard when performing this step.