Test K: The A/C Is Always on

PINPOINT TEST K: THE A/C IS ALWAYS ON

K1-K3:

K3-K5:

K5-K7:

K8:

Normal Operation
Under normal operation, in EATC systems, when A/C is requested, a message is sent over the bus to the PCM. Voltage is provided to the A/C cycling switch through circuit 298 (VT/OG)/348 (VT). Voltage is sent from the A/C cycling switch to the dual-function pressure switch through circuit 441 (RD/YE). Voltage is sent from the dual-function pressure switch to the PCM through circuit 879 (DG/WH).

Under normal operation, in manual climate control systems, Voltage is provided to the function selector switch through circuit 1087 (OG). When A/C is requested, a voltage is sent from the function selector switch to the A/C cycling switch through circuit 348 (VT). Voltage is sent from the A/C cycling switch to the dual-function pressure switch through circuit 441 (RD/YE). Voltage is sent from the dual-function pressure switch to the PCM through circuit 879 (DG/WH).

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 361 (RD). Ignition voltage for the A/C clutch relay switch is provided through circuit 883 (PK/LB). When the relay is energized, ignition voltage is supplied to the A/C clutch solenoid through circuit 347 (BK/YE). Ground is supplied for the A/C clutch through circuit 57 (BK).

Possible Causes
- A short to voltage in circuit 347 (BK/YE), 348 (VT), 441 (RD/YE) or 879 (DG/WH)
- A short to ground in circuit 331 (PK/YE)
- PCM
- Function selector switch
- A/C control relay
- A/C clutch air gap