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Pinpoint Test B : P0645: Notes

WARNING: This page is about a different car, the 2018 Lincoln Continental. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Automatic Climate Control System for schematic and connector information.

Normal Operation and Fault Conditions 

Voltage is provided to the A/C clutch relay coil. 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, energizing the A/C clutch relay.

DTC Fault Trigger Conditions 

DTC Description Fault Trigger Conditions
P0645 A/C Clutch Relay Control Circuit The DTC sets when the PCM grounds the relay circuit and more voltage than expected 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.

Possible Sources 

Visual Inspection and Diagnostic Pre-checks 

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