The A/C compressor clutch hub must sit at a specific distance from the spinning pulley. This distance is called the clutch gap. If the gap is too wide, the electromagnetic coil won't have enough strength to pull the hub in, and the compressor won't turn. If the gap is too narrow, the hub will drag against the pulley, generating friction heat. Technicians adjust this gap by adding or removing thin metal shims on the compressor shaft behind the clutch plate.
Mechanic Glossary
A/C Compressor Clutch Gap Adjustment
The process of adding or removing metal shims behind the A/C compressor clutch hub to set the correct distance from the pulley.
Frequently Asked Questions
Most compressors require a gap between 0.015 and 0.030 inches (0.35 to 0.75 mm). Check your service manual for exact specs.
The A/C works fine when the engine is cold, but stops working once the engine compartment heats up. Heat increases resistance in the coil, weakening its magnetic pull.
Insert a feeler gauge between the compressor clutch hub and the pulley face while the engine is turned off.