Compressor Clutch Does Not Engage

HVAC COMPRESSOR CLUTCH DOES NOT ENGAGE

DIAGNOSTIC AIDS
- A thermal switch that is located on the back of the compressor will open when compressor temperatures reach 155°C (311°F). When the thermal switch is open, supply voltage is removed from the A/C compressor clutch.
- The condition may be intermittent. Refer to Diagnostic Aids for Circuit Testing and Wiring Repair procedures.

TEST DESCRIPTION

Steps 1-3:

Steps 4-6:

Steps 7-12:

Steps 13-18:

Steps 19-26:

Steps 27-33:

Steps 34-38:

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 module (IPM) 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.