A/C Compressor Clutch
An electromagnetic clutch that cycles the A/C compressor on and off when cooling is requested.
The A/C compressor clutch is an electromagnetic device mounted on the front of the air conditioning compressor. It allows the compressor to engage and pump refrigerant only when cooling is requested, reducing engine load and saving fuel when the A/C is off.
The assembly consists of a belt-driven pulley (which spins constantly with the engine's serpentine belt), a clutch hub plate attached to the compressor shaft, and an electromagnetic coil mounted behind the pulley.
When the driver turns on the A/C, the climate control computer sends electrical current to the electromagnetic coil, creating a magnetic field. This field pulls the clutch hub plate against the spinning pulley, locking them together and turning the compressor internals.
Over time, the clutch friction material can wear down, or the electromagnetic coil can burn out. Symptoms of a bad compressor clutch include the A/C pulley spinning but the compressor not engaging, a screeching noise when the A/C is turned on, or the A/C blowing warm air.