Compressor Magnetic Clutch
WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
Powertrain Control Module (PCM) controls compressor (magnetic) clutch. When A/C is on, PCM closes A/C relay, energizing compressor clutch. When either high pressure or compressor cycling switch is open, PCM will open A/C relay, de-energizing compressor clutch.