A/C Compressor Control

The Powertrain Control Module (PCM) and the Body Control Module (BCM) share the hardware and the software for control of the A/C compressor clutch. The PCM and the BCM communicate this information over the Class 2 serial data line.

The control compressor clutch function looks at the other BCM compressor functions and determines if any of these functions are disabling the engagement of the compressor clutch.

The BCM performs the following software functions:
^ Limits low speed compressor operation
^ Prevents clutch slippage
^ Monitors high coolant temperature
^ Monitors for overpressure
^ Determines low ambient pressure
^ Controls the compressor clutch

The PCM performs the following functions:
^ Prevents compressor overspeed
^ Limits compressor speed (in PARK or NEUTRAL)
^ Drives the compressor clutch

The drive compressor clutch function looks at the BCM request and at the other PCM compressor functions. This determines whether or not the compressor clutch should be engaged.