Normal Operation

Under normal operation, voltage is provided to the A/C clutch relay coil through circuit CBK03 (GY). When A/C is requested, and A/C line pressures allow, a ground is provided to the A/C clutch relay coil from the PCM through circuit CH302 (WH/BN), energizing the A/C clutch relay.

• DTC P0645 (A/C Clutch Relay Control Circuit) - The DTC sets when the PCM grounds the relay circuit and excessive current draw is detected on the relay circuit. The DTC also sets when the relay circuit is OFF and no voltage is detected on the relay circuit. The PCM expects to detect voltage coming through the relay coil to the relay circuit when it is not grounding it.

This pinpoint test is intended to diagnose the following: 

• Wiring, terminals or connectors
• A/C clutch relay
• PCM