Controls and Compressor Operation

WARNING: This page is about a different car, the 2015 Ford C-Max. However, it is still accessible from the selected car via links, so may be relevant.

Climate control commands are input through the HVAC control module. On vehicles equipped with Sony® Sound inputs can also be commanded through voice commands or the touch screen.

When the A/C is requested, the HVAC control module sends the message over the MS-CAN to the GWM. The GWM then forwards the message over the HEV High Speed Controller Area Network (HS-CAN).

The A/C demand message is sent from the SOBDMC over the HEV High Speed Controller Area Network (HS-CAN) to the ACCM. The ACCM engages the A/C electric compressor when 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 an ambient air temperature below approximately 33.8°F (1°C).
The BCM does not detect an evaporator discharge air temperature below approximately 33.8°F (1°C).

The ACCM engages the A/C electric compressor when it receives the A/C demand message and target Revolutions Per Minute (RPM) request. Instead of cycling on and off like a traditional A/C compressor, the ACCM raises or lowers the A/C electric compressor speed as required.

The HVAC control module adjusts the air inlet door depending on the humidity measured by the in-vehicle temperature and humidity sensor. If the vehicle cabin becomes too humid and recirculated air is selected, the HVAC control module adjusts the air inlet door to allow more fresh air. When the humidity level drops, it may adjust back to partial recirculated air. The HVAC control module also adjusts the system based on in-vehicle temperature.

The sunload sensor supplies information to the HVAC control module indicating the intensity of the sun on the vehicle. The HVAC control module adjusts the system based on the intensity.