Compressor HVAC: Description and Operation

Battery voltage is supplied through fuse 35 to the A/C compressor clutch relay contacts at all times.

With the ignition switch in ON (II), voltage is applied to the coil of the A/C compressor clutch relay through fuse 13. When you push the A/C switch to the "in" position (ON), and the heater fan switch is in position 1, 2, 3, or 4, a "ground" input is provided to the Engine Control Module (ECM) through the A/C thermostat and the A/C pressure switch.

The A/C compressor clutch relay is grounded by the engine control module (ECM). When energized, the A/C compressor clutch relay allows battery voltage to turn ON the A/C compressor clutch.

The A/C ON indicator light comes ON when you push the A/C switch to the "in" position (ON).