Compressor Clutch Relay: Description and Operation

Wide Open Throttle A/C Cut-Off
The wide open throttle A/C cutoff relay (may be referred to as the A/C clutch relay) is normally open. There is no direct electrical connection between the A/C switch or EATC Module and the A/C clutch. The PCM will receive a signal indicating that A/C is requested (for some applications, this message is sent through the BUS + and BUS - circuits). When A/C is requested, the PCM will check other A/C related inputs that are available (such as ACP (SW), A/C Cycling Switch (ACCS)). If these inputs indicate A/C operation is OK, and the engine conditions are OK (such as coolant temperature, engine rpm, throttle position), the PCM will ground the Wide Open Throttle A/C (WAC) output, closing the relay contacts and sending voltage to the A/C clutch.