A/C Compressor Clutch/Coil

A/C COMPRESSOR CLUTCH COIL

The air conditioning compressor clutch coil electrical circuit is controlled by the powertrain control module (PCM) through the A/C compressor clutch relay, which is located in the integrated power module (IPM) in the engine compartment. Begin testing of a suspected compressor clutch coil problem by performing the preliminary checks.


PRELIMINARY CHECKS

1. If the A/C compressor clutch will not engage, verify the refrigerant charge level. If the refrigerant charge level is OK, go to STEP 2. If the refrigerant charge level is not OK, adjust the refrigerant charge as required.

2. If the A/C compressor clutch still will not engage, disconnect the wire harness connector for the A/C pressure transducer and check for battery current at the connector with the engine running and the A/C-heater control set to the A/C mode. If OK, go to TESTS. If not OK, refer to Body Diagnostic Procedures to perform further diagnosis.


TESTS

3. Verify the battery state of charge.

4. Connect an ammeter (0 to 10 ampere scale selected) in series with the clutch coil feed terminal. Connect a voltmeter (0 to 20 volt scale selected) to measure voltage across the battery and the clutch coil.

5. With the heater-A/C control in the A/C mode and the blower at low speed, start the engine and allow it to run at a normal idle speed.

6. The compressor clutch should engage immediately, and the clutch coil voltage should be within two volts of the battery voltage. If the coil voltage is not within two volts of battery voltage, test the clutch coil feed circuit for excessive voltage drop. If the compressor clutch does not engage, refer to Body Diagnostic Procedures to perform further diagnosis.

7. For the acceptable A/C clutch coil current draw specifications refer to Heating and Air Conditioning specifications. Specifications apply for a work area temperature of 21° C (70° F). If voltage is more than 12.5 volts, add electrical loads by turning on electrical accessories until voltage reads below 12.5 volts.
a. If the compressor clutch coil current reading is zero, the coil is open and must be replaced.
b. If the compressor clutch coil current reading is four amperes or more, the coil is shorted and must be replaced.