Test J: The Air Conditioning (A/C) Is Always On

PINPOINT TEST J: THE AIR CONDITIONING (A/C) IS ALWAYS ON

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Normal Operation
Under normal operation, when A/C is requested, voltage is sent from the electronic automatic temperature control (EATC) module or function selector switch to the A/C cycling switch through circuit 348 (VT). Voltage is sent from the A/C cycling switch to the (gasoline engine) A/C high pressure switch or (diesel engine) dual function pressure switch through circuit 441 (RD/YE). Voltage is sent from the A/C high pressure switch or dual function pressure switch to the powertrain control module (PCM) through circuit 439 (TN/RD).

The PCM provides a ground for the A/C clutch relay coil through circuit 331 (PK/YE). The A/C clutch relay coil receives ignition voltage through circuit 391 (RD/YE). Ignition voltage for the A/C clutch relay switch is provided through circuit 326 (WH/VT). When the relay is activated, ignition voltage is supplied to the A/C clutch solenoid through circuit 321 (GY/WH). Ground is supplied for the A/C clutch through circuit 57 (BK).

Possible Causes
- A short to voltage in circuits 321 (GY/WH), 348 (VT), 441 (RD/YE) or 439 (TN/RD)
- A short to ground in circuit 331 (PK/YE)
- PCM
- Electronic automatic temperature control (EATC) module
- A/C control relay
- A/C clutch air gap