Compressor Clutch Relay: Description and Operation

Relay Locations:

This relay is controlled by the Single Board Engine Controller (SBEC) and the A/C switch (inside vehicle). Voltage is supplied to the compressor clutch via the A/C clutch relay; if the engine controller has applied the ground (ENERGIZED) to the A/C clutch relay. The A/C clutch relay is ENERGIZED when the engine is RUNNING and the A/C control switch and blower switch are in the ON position, and the engine controller applies the ground to the relay circuit.

If the SBEC senses a wide open throttle or low idle speed condition, via the throttle position sensor, it will remove the ground to the A/C clutch relay, DE-ENERGIZING the relay, which will prevent A/C clutch engagement.

The A/C clutch relay also controls the radiator fan relay. When the air conditioning (A/C) is selected the relay supplies power to the compressor clutch as well as the radiator fan relay, allowing the radiator cooling fan to operate when the A/C has been selected. The engine controller will delay the activation of the A/C relay for a specific amount of time after engine start-up.