Compressor Clutch Coil: Testing and Inspection

1. Verify battery state of charge. (Test indicator 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 2 volts of the battery voltage. If the A/C clutch does not engage, test the fusible link.
5. The A/C clutch coil is acceptable, if the current draw is 2.0 to 3.7 amperes at 11.5 to 12.5 volts at clutch coil with room ambient 21° ± 3°C (700 ± 5°F). Where voltage is more than 12.5 volts, add electrical loads as needed by increasing blower speed and/or switching other electrical accessories on. 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 2 volts of the battery voltage, check the circuit external to the clutch coil for excessive voltage drop and repair accordingly.