Automotive AC – AC Clutch Coil

The AC clutch coil is used to create a magnetic field that attracts the front plate toward the pulley to engage the internal parts of the compressor. Below are the strategies to troubleshoot the clutch coil.

Testing the AC Clutch Coil

1. Test for power and ground supplied to the coil. To do this, connect
the voltmeter leads to the compressor coil connector by back-probing
the terminals. Turn on the AC and measure the voltage drop across
the terminals. If source voltage is available, the coil is faulty and
needs to be replaced.
2. Test the resistance of the coil. To do this, disconnect the compressor
coil connector. Connect the ohmmeter leads across the terminals of
the coil. The reading should be 2 to 5 ohms.
3. Run direct voltage to the coil by connecting a fused jumper wire to source voltage and run the other end of the wire to the positive terminal of the compressor coil. This can also be accomplished on the vehicle by jumping across the AC clutch relay with a toggle switch or a jumper wire.

The AC compressor clutch coil is located on the front side of the compressor and is typically serviced by replacing the compressor

Direct power and ground can be supplied to the AC compressor clutch coil by connecting a power and ground wire to the coil connector. The compressor should make a clicking sound when power and ground are directly connected to the

The supply voltage to the AC clutch coil can be tested by back-probing the terminals at the coil connector with the AC commanded on. The voltage reading should be about 12 volts if the system is operating

An ohmmeter can be used to measure the resistance of the AC compressor clutch coil. This test is performed with the coil connector disconnected from the harness. Care should be taken to only use test wires that will not damage the terminals of the clutch coil. The expected resistance for this test is typically between 2 to 5 ohms. Always refer to quality service information for exact

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