GM Service Manual Online
For 1990-2009 cars only

Compressors are belt driven from the engine crankshaft through the compressor clutch pulley. The compressor pulley rotates freely without turning the compressor shaft until the electromagnetic coil is energized. When voltage is applied in order to energize the clutch coil, a clutch plate and hub assembly is drawn rearward toward the pulley. The magnetic force locks the clutch plate and the pulley together as one unit in order to drive the compressor shaft.

Ensure that any replacement compressors from service parts has the exact amount of oil in the crankcase that was used in the old compressor.