Normal Operation

WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

Under normal operation, when A/C is requested, a message is sent over the bus to the PCM (DATC systems) or sends voltage to the PCM through circuit 348 (VT) (manual climate control systems). The PCM receives input from the A/C cycling switch through circuit 347 (BK/YE) and from the A/C pressure cutoff switch through circuit 441 (RD/YE). Ground is provided to the A/C cycling switch and A/C pressure cutoff switch through circuit 570 (BK/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 1139 (VT/YE). Ignition voltage for the A/C clutch relay switch is provided through circuit 1003 (GY/WH). 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 1205 (BK).