The operation of the A/C compressor clutch is controlled by the powertrain control module (PCM) and the instrument panel cluster (IPC). The IPC receives an a/c request signal from the heater a/c control assembly through circuit 66. The IPC then sends a UART serial data message to the PCM through circuit 800. Power for the a/c compressor clutch relay coil is supplied by the ERLS fuse and circuit 439. The switched side of the a/c compressor clutch relay is supplied through the A/C fuseand CKT 440. When the PCM receives an a/c request message from the IPC, the PCM grounds circuit 459 allowing the a/c compressor clutch relay to engage. Ground for the a/c compressor clutch is supplied through circuit 150.