The A/C clutch relay is located in the underhood fuse block (UHFB). The ECM controls the A/C clutch by supplying a ground to the A/C clutch relay. The ECM controls an internal driver is normally open and supplies a ground to the A/C clutch relay whenever the A/C clutch relay is commanded On. The A/C clutch relay control circuit is monitored for low and high voltage and open circuit faults. DTC P0647 will set if the ECM detects a feedback voltage above a calibrated value in the A/C clutch relay control circuit when the relay is commanded On.

DTC P0647 will set if the ECM detects the A/C clutch relay control feedback voltage at the ECM is above 4.6 volts when the relay is being commanded On when:

DTC P0647 diagnostic runs continuously with ignition On and A/C clutch relay commanded On.

P0647 is a (type D) DTC

Inspect harness for chaffed wiring that may cause a short to voltage condition on circuit 459.