Powertrain Control Module

Powertrain Control Module (PCM) indirectly controls power to compressor clutch coil. When PCM receives an A/C request signal, it grounds coil circuit of A/C WOT relay. Contacts in A/C WOT relay close, allowing power to coil circuit of A/C WOT relay. This causes A/C relay contacts to close, allowing power to compressor clutch coil.

PCM shuts off compressor clutch during engine starting, high engine speed, heavy acceleration, high engine coolant temperature, or low engine idle (about 200 RPM less than specification).