A/C Request Signal

The A/C system can be engaged by pressing the A/C switch. The A/C switch will illuminate when the A/C switch is pressed to the ON position. The MAX A/C, front defroster and defog mode selections will also automatically run the A/C compressor. The A/C LED will not illuminate in these modes of operation. The HVAC control assembly sends a A/C request message to the Body Control Module (BCM) which sends a class 2 message to the Powertrain Control Module (PCM). The A/C compressor clutch relay control switch in the PCM closes creating a ground and energizing the A/C compressor relay coil which closes the A/C compressor clutch relay switch energizing the A/C compressor clutch.