A/C Request

STANDARD HVAC
A/C request is made by the HVAC control head supplying voltage to circuit 66 to the BCM. The BCM will then request the serial data link to the engine controller to operate the compressor. The BCM provides evaporator freeze protection by monitoring engine speed and ambient temperature.

AUTOMATIC CLIMATE CONTROL
The ACC system will request air compressor over serial data from the ACC module to the BCM. The BCM will send the request on to the PCM or ECM, if request is valid.