Compressor Clutch Relay: Description and Operation

Engine Control Components

Air Conditioning (A/C) Clutch Relay (A/CCR)

Note: The PCM parameter identifiers (PIDs) wide open throttle air conditioning cutoff (WAC) and wide open throttle air conditioning cutoff fault (WAC_F) are used to monitor the A/CCR output.

The A/CCR is wired normally open. There is no direct electrical connection between the A/C switch or electronic automatic temperature control (EATC) module and the A/C clutch. The PCM receives a signal indicating that A/C is requested. For some applications, this message is sent through the communications network. When A/C is requested, the PCM checks other A/C related inputs that are available, such as A/C pressure switch and A/C cycling switch. If these inputs indicate A/C operation and the engine conditions are OK (coolant temperature, engine RPM, throttle position), the PCM grounds the A/CCR output, closing the relay contacts and sending voltage to the A/CCR.