A/C System
CIRCUIT OPERATIONWhen the A/C switch is CLOSED or the Defrost switch is moved to the ON position, and the evaporator temperature is in the normal limits, the Body Control Module (BCM) sends a signal to the Powertrain Control Module (PCM), over the CCD Bus, requesting A/C operation.
After receiving this input, the PCM activates the A/C compressor by grounding the C28 circuit, which is attached to the coil side of the A/C clutch relay. This relay is located in the Power Distribution Center (PDC). Power for the coil side of the relay is supplied on the F18 circuit. The F15 circuit is protected by a 10 Amp fuse located in cavity 9 of the Power Distribution Center (PDC).
When the coil is energized contacts in the relay CLOSE connecting circuits A16 and C3. Circuit A16 is protected by a 40 Amp fuse located in cavity 17 of the PDC and also supplies power for the radiator fan relays. The C3 circuit connects from the relay to the A/C compressor clutch.
The A/C compressor clutch receives this current and creates a magnetic field, energizing the clutch. The A/C compressor clutch is case grounded to the A/C compressor.
The A/C compressor clutch has a diode located in it. This diode is used to control the induced voltage resulting from the magnetic field collapsing when the clutch is disengaged.
The A/C compressor clutch relay is also used by the PCM to disengage the compressor in a Wide-Open Throttle (W.O.T.) condition.