Hybrid Climate Control System Operation

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For the passenger side temperature setting on hybrid vehicles equipped with dual-zone Electronic Automatic Temperature Control (EATC) and a Front Controls Interface Module (FCIM) built on or after 4/08/2009 to be functional, a passenger must be seated in the front passenger seat. If the front passenger seat is not occupied, the HVAC module will control the system based only on the driver side temperature setting. The HVAC module receives a Medium Speed Controller Area Network (MS-CAN) signal from the FCIM to indicate if the front passenger seat is occupied.

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 (HS-CAN) 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 Air Conditioning Compressor Module (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 PCM monitors the evaporator discharge temperature from the HVAC module 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.