Normal Operation

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

Under normal operation, when A/C is requested a signal is sent from the control module to the Smart Junction Box (SJB) through circuit 1397 (GY/WH) (Single-zone EMTC only) or over the SCP BUS (Dual-zone EATC and EMTC only). The SJB sends a message over the SCP bus to the PCM. Voltage is supplied to the A/C cycling switch by circuit 298 (VT/OG) and to the PCM through circuit 347 (BK/YE).

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 931 (OG). When the relay is activated, ignition voltage is supplied to the A/C clutch solenoid through circuit 883 (PK/LB). Ground is supplied for the A/C clutch through circuit 1205 (BK).