Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Powertrain Control Module: Description and Operation
Air Conditioning (A/C) Clutch Relay-PCM Output
AIR CONDITIONING (A/C) CLUTCH RELAY-PCM OUTPUT
Fig. 2 Power Distribution Center (PDC)
The A/C relay is located in the Power Distribution Center (PDC). The PDC is located in the engine compartment (Fig. 2). Refer to label on PDC
cover for relay location.
The Powertrain Control Module (PCM) activates the A/C compressor through the A/C clutch relay The PCM regulates A/C compressor operation
by switching the ground circuit for the A/C clutch relay on and off.
When the PCM receives a request for A/C from A/C evaporator switch, it will adjust Idle Air Control (IAC) motor position. This is done to
increase idle speed. The PCM will then activate the A/C clutch through the A/C clutch relay The PCM adjusts IAC stepper motor position to
compensate for increased engine load from the A/C compressor.
By switching the ground path for the relay on and off, the PCM is able to cycle the A/C compressor clutch. This is based on changes in engine
operating conditions. The PCM will also de-energize the relay if coolant temperature exceeds 125°C (257°F).
