Control Module HVAC: Description and Operation

When the air conditioning is ON during normal engine operation, the Air Conditioning Control Module (ACM) informs the Engine Control Unit (ECU) of the additional engine load. The ECU compensates for this load by monitoring and adjusting engine idle speed. When the engine goes to wide open throttle, the ECU sends a signal to the ACM to disengage the air conditioning compressor. This is done to allow full engine power to be delivered to the drive train.