A/C System
CIRCUIT OPERATIONWhen the A/C or the defrost switch is put in the ON position, and the A/C cycling switch, low pressure cut-out switch, and the high pressure switch are CLOSED, the Powertrain Control Module (PCM) receives a request for A/C.
After receiving this input, the PCM activates the A/C compressor by grounding the C28 circuit on the coil side of the A/C Compressor Clutch relay Power for the coil side of the relay is supplied on the bus bar located in the Power Distribution Center (PDC). With the coil energized, current flows from the 10 amp fuse in the PDC on circuit A17 through the CLOSED contacts in the relay, on the C3 circuit to the A/C compressor clutch.
The A/C compressor clutch receives this voltage and creates a magnetic field energizing the clutch. Ground for the coil is provided at the right headlamp ground.
The connector at the A/C compressor 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 diode provides a path for the voltage to protect other components and systems.
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.