A/C Request

When an A/C request is received by the PCM, the PCM sends the request over the HS-CAN to the ACCM when all of the following conditions are met:

• the refrigerant pressure is not excessively high or low.
• the ambient air temperature is above approximately 4 °C (39.2 °F).
• the evaporator discharge air temperature is above approximately 2 °C (36 °F).

When the ACCM receives the A/C request message, it will engage the A/C electric compressor. Instead of cycling ON and OFF like a traditional A/C compressor, the A/C electric compressor speeds up or slows down 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 and the HVAC control module adjusts the system based on the intensity.