Hybrid Climate Control System Operation

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

When an A/C request is made by the HVAC module, a message is sent from the HVAC module over the Medium Speed Controller Area Network (MS-CAN) bus to the Instrument Cluster (IC), then from the IC through the High Speed Controller Area Network (HSCAN) bus to the PCM.

When an A/C request is received from the HVAC module, an A/C demand message is sent from the PCM over the HS-CAN bus to the ACCM if all of the following conditions are met:

The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
The PCM does not detect excessively high engine coolant temperature.
The PCM does not detect an ambient air temperature below -1°C (30°F).
The PCM has not detected a Wide Open Throttle (WOT) condition.
The HVAC module does not detect an evaporator discharge air temperature below 2°C (36°F).

When the ACCM receives the A/C demand message, it will engage. Instead of cycling ON and OFF like a traditional A/C compressor, the ACCM monitors the evaporator discharge temperature to raise or lower the electric A/C compressor speed as required. When the HVAC module is OFF or not requiring A/C operation, the electric A/C compressor will be OFF.