Compressor Clutch: Description and Operation

A/C Compressor Clutch - Typical:

The A/C compressor clutch assembly consists of a stationary electromagnetic A/C clutch field coil, pulley bearing and pulley assembly, clutch plate and shims. These components provide the means to engage and disengage the A/C compressor from the engine accessory drive belt.

The A/C clutch field coil and the pulley bearing and pulley assembly are both retained on the nose of the A/C compressor with snap rings. The clutch plate is keyed or splined to the compressor shaft and secured with a nut.

The A/C compressor clutch components provide the means to engage and disengage the A/C compressor from the engine accessory drive belt. When the electromagnetic A/C clutch field coil is energized, it magnetically draws the clutch plate into contact with the clutch pulley and drives the compressor shaft. When the coil is not energized, the pulley freewheels on the clutch hub bearing, which is part of the pulley.

A/C clutch engagement is controlled by the following:
- A/C-heater mode control
- A/C clutch relay
- A/C pressure transducer (gasoline engines)
- A/C high pressure switch (diesel engine)
- A/C low pressure switch
- Powertrain control module (PCM) or engine control module (ECM) (depending on application)

The A/C compressor clutch components cannot be repaired and, if faulty or damaged, they must be replaced.