Controls and Compressor Cycling

Climate control commands are inputted through the Heating, Ventilation, and Air Conditioning (HVAC) module and 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 Heating, Ventilation, and Air Conditioning (HVAC) module sends the message over the Medium Speed Controller Area Network (MS-CAN) to the Gateway Module (GWM). The Gateway Module (GWM) then forwards the message to the Powertrain Control Module (PCM) over the High Speed Controller Area Network (HS-CAN).

An A/C demand message is sent from the Powertrain Control Module (PCM) over the High Speed Controller Area Network (HS-CAN) to the Air Conditioning Control Module (ACCM) if all of the following conditions are met:

• The Powertrain Control Module (PCM) does not detect excessively high or low refrigerant pressure from the A/C  pressure sensors.
• The Powertrain Control Module (PCM) does not detect an ambient air temperature below approximately 4°C (39.2°F).
• The Powertrain Control Module (PCM) does not receive a message from the Body Control Module (BCM) detecting an evaporator discharge air temperature below approximately 2°C (36°F).

When the Air Conditioning Control Module (ACCM) receives the A/C  demand message, it will engage. Instead of cycling ON and OFF like a traditional A/C  compressor, the Powertrain Control Module (PCM) monitors the evaporator discharge temperature from the Heating, Ventilation, and Air Conditioning (HVAC) module to raise or lower the electric A/C  compressor speed as required.

The Heating, Ventilation, and Air Conditioning (HVAC) 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 Heating, Ventilation, and Air Conditioning (HVAC) 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 Heating, Ventilation, and Air Conditioning (HVAC) module also adjusts the system based on in-vehicle temperature.

The autolamp/sunload sensor supplies information to the Heating, Ventilation, and Air Conditioning (HVAC) module indicating the intensity of the sun on the vehicle and the Heating, Ventilation, and Air Conditioning (HVAC) module adjusts the system based on the intensity.