What Is The AC Compressor Clutch Air Gap and How To Adjust It

The correct AC compressor clutch air gap is critical to proper compressor engagement

Auto parts stores sell AC compressor clutch air gap shims

When you turn on your car’s AC, the compressor clutch coil energizes and pulls in the clutch disc so it contacts the compressor pulley and spins the compressor shaft. When not engaged, the clutch disc sits away from the compressor pulley by a specified distance. This is referred to the compressor clutch air gap. If the gap is too small, the clutch disc can rub against the pulley when the AC isn’t on. If the gap is too large, the clutch coil’s magnetic field can’t pull it in to contact the pulley, or pulls it in but can’t keep it engages and it slips.

In other words, the air gap is critical to proper AC operation.

How to adjust the AC compressor clutch air gap

The air gap is determined by the thickness of a shim washer that’s located on the AC compressor shaft, between the pulley and the clutch disc. To adjust the gap, measure the existing gap using a feeler gauge. Then compare the gap to the specs listed below.

If the gap is too small, remove the clutch disc and install a larger shim washer. If it’s too large, install a smaller shim washer. Find air gap shims at any auto parts store like O’Reaillys

Here are the AC compressor clutch air gap specs for many common AC compressor clutches

Nippondenso AC air gap specs

Model: C171, A590 is adjusted with shims to .020″ – .035″

Model: 10PA17C is adjusted with shims to .014″ – .026″

Model: 6C17, 10PA17 is adjusted with shims to .020″ – .035″

All Others are adjusted with shims to.020″ – .035″

Shaft nut torque on Nippondenso AC compressors is 12 ft/lbs

Ford AC air gap specs

Model:  FS6, 6P148 is adjusted with shims to .020″ – .035″

Model:  10PA17C, 10P13 is adjusted with shims to .020″ – .035″

Model: 10P15F is adjusted with shims to .020″ – .035″

Model:  10P15A is adjusted with shims to .016″ – .028″

Model:  FX15, FS10 is adjusted with shims to .013″ – .033″

Shaft nut torque on Ford AC compressors is 12 ft/lbs

GM AC air gap specs

Model: 10PA20, 10P15 is adjusted with shims to .014″ – .026″

All Others are adjusted with shims to .020″ – .035″

Shaft nut torque on GM AC compressors is 12 ft/lbs

©, 2018 Rick Muscoplat