Some compressor clutch circuits contain a thermal limiter switch that senses compressor surface temperature. Some A/C compressor clutch circuits also contain a low-pressure cutoff switch.
A/C safety switches .
A/C systems have load-sensitive electrical switches; such as the low-pressure switch, high-pressure switch, pressure cycling, and power steering. Not all the switches, however, are used in all vehicles. The pressure switches are used to prevent compressor or component damage in the event of extremely high or low-system pressures.
Compressors are equipped with an electromagnetic clutch as part of the compressor pulley assembly. The clutch is designed to engage the pulley to the compressor shaft when the clutch coil is energized.
Nearly all clutch assemblies have a clearance specification for the distance between the clutch and the pressure plate.
Compressor air gap out of specifications.
This clearance is measured with a feeler gauge. If the clearance is too great, the clutch may slip intermittently and cause a scrapping or squealing noise. Damage to the compressor and poor ac performance will result from this fault.