Compressor Clutch Coil: Testing and Inspection

COMPRESSOR CLUTCH/COIL DIAGNOSIS
The air conditioning compressor clutch electrical circuit is controlled by the Powertrain Control Module. It is located in the engine compartment outboard of the battery

If the compressor clutch does not engage verify refrigerant charge.

If the compressor clutch still does not engage check for battery voltage at the pressure transducer located on the liquid line, If voltage is not detected, refer to Powertrain Diagnostic Procedures for diagnostic information.

If voltage is detected at the pressure transducer, connect pressure transducer and check for battery voltage between the compressor clutch connector terminals.

If voltage is detected, perform A/C Clutch Coil Tests.

Tests
1. Verify battery state of charge. (Test indicator in battery should be green).
2. Connect an ammeter (0-10 ampere scale) in series with the clutch coil terminal. Use a voltmeter (0-20 volt scale) with clip leads measuring voltage across the battery and A/C clutch.
3. With A/C control in A/C mode and blower at low speed, start the engine and run at normal idle.
4. The A/C clutch should engage immediately and the clutch voltage should be within two volts of the battery voltage. If the A/C clutch does not engage, test the fuse.
5. The A/C clutch coil is acceptable if the current draw is 2.0 to 3.7 amperes at 11.5 - 12.5 volts at clutch coil. This is with the work area temperature at 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.
6. If coil current reads zero, the coil is open and should be replaced. If the ammeter reading is 4 amperes or more, the coil is shorted and should be replaced. If the coil voltage is not within two volts of the battery voltage, test clutch coil feed circuit for excessive voltage drop.