A/C Compressor
WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Chevrolet Cavalier, 2001 Pontiac Sunfire, and 2001 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) receives an A/C request signal from heater-A/C control panel and transmits this signal over class 2 serial data line to Powertrain Control Module (PCM). PCM engages A/C compressor clutch.