Compressor Clutch Coil: Description and Operation

A/C Compressor Clutch - Typical:

The compressor dutch assembly consists of a stationary electromagnetic coil, a hub bearing and pulley assembly, and a clutch plate. The electromagnetic coil unit and the hub bearing and pulley assembly are each retained on the nose of the compressor front housing with snap rings. The clutch plate is keyed to the compressor shaft and secured with a retainer. These components provide the means to engage and disengage the compressor from the engine serpentine accessory drive belt.

When the clutch coil is energized, it magnetically draws the clutch into contact with the 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. The compressor clutch and coil are the only serviced parts on the compressor.

A/C compressor clutch engagement is controlled by the following components:
- A/C-heater mode control switch
- A/C low pressure switch
- A/C high pressure switch
- A/C compressor clutch relay
- Powertrain Control Module (PCM)
The PCM may delay compressor dutch engagement for up to thirty seconds.