Test I: The Air Conditioning (A/C) Is Inoperative/Does Not Operate Correctly
PINPOINT TEST I: THE AIR CONDITIONING (A/C) IS INOPERATIVE/DOES NOT OPERATE CORRECTLYI1-I5:
I5-I7:
I7-I9:
I9-I11:
I11-I12:
I12-I14:
I14-I15:
I16-I18:
I18-I20:
I20 Continued:
I20-I22:
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
- Fuse(s)
- An open in circuits 57 (BK), 321 (GY/WH), 326 (WH/VT), 331 (PK/YE), 348 (VT), 391 (RD/YE), 441 (RD/YE) or 439 (TN/RD)
- PCM
- Electronic automatic temperature control (EATC) module
- Function selector switch
- A/C cycling switch
- A/C high pressure switch
- Dual-function pressure switch
- A/C compressor clutch field coil
- A/C control relay
- A/C clutch air gap