2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2208
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0645
- A/C Clutch Relay Control Circuit
Diagnostic Fault Information
Circuit System Description
Ignition voltage is supplied directly to the A/C compressor clutch relay. The engine control module (ECM) controls the relay by grounding the A/C
clutch relay control circuit. When the ECM is commanding a component ON, the voltage of the control circuit should be near 0 volt. When the
ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage.
Conditions for Running the DTC
* The ignition voltage is between 11-18 volts.
* The engine speed is greater than 600 RPM.
* An A/C request is made.
Conditions for Setting the DTCs
The ECM detects an open on the control circuit of the A/C compressor clutch relay when commanded OFF with the engine in crank or run status.
Action Taken When the DTC Sets
The ECM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze
Frame data.
Conditions for Clearing the DTC
A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
Reference Information
Schematic Reference
HVAC Schematics (See: Heating and Air Conditioning/Diagrams/Electrical Diagrams/HVAC - Automatic)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
* Air Delivery Description and Operation (See: Heating and Air Conditioning/Description and Operation/HVAC - Automatic/Air Delivery
Description and Operation)
* Air Temperature Description and Operation (See: Heating and Air Conditioning/Description and Operation/HVAC - Automatic/Air
Temperature Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
