Operation CHARM: Car repair manuals for everyone.

Compressor Controls

CIRCUIT OPERATION
The compressor for the air conditioning system is belt-driven by the engine. The A/C Compressor Clutch is used to turn the compressor on and off. This controls the cooling and also removes the air conditioning load from the engine when needed. When the Mode Selector Switch is in MAX, NORM, BILEVEL, or DEF, and the refrigerant level is adequate, the ambient air temperature above 0°C (32°F), the A/C Compressor Clutch will engage the Compressor.

Pressure Cycling Switch
The Pressure Cycling Switch turns the Compressor off when the evaporator temperature is low enough to cause icing. The switch is located in the low pressure, or vapor side of the system. It opens when the refrigerant pressure is less than 172 kPa (25 psi). This opens the circuit to the A/C Compressor Clutch. This switch closes to turn the compressor on again when the evaporator temperature and~pressure rise enough to require more cooling.

A/C Wide-Open Throttle Cut-Out Switch
The A/C Wide-Open Throttle Cut-Out Switch opens with the accelerator fully depressed. This turns off the A/C Compressor Clutch to remove the air conditioner load on the engine for better engine performance.