Schematic Reference: HVAC Schematics

DEFINITION: The A/C compressor clutch will not disengage when an A/C request has not been made and a Powertrain DTC has not been set.

Did you review the HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

1. Start the engine.
2. Place the blower motor switch in the OFF position.
3. Place the A/C switch in the OFF position.

Does the A/C compressor operate?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

With the scan tool, observe the Commanded A/C parameter in the powertrain control module (PCM) Data List.

Does the scan tool indicate the A/C relay commanded parameter is ON?

Go to Step 4

Go to Step 7

With the scan tool, observe the A/C Control Head (Desired) parameter in the body control module (BCM) A/C Information List.

Does the scan tool display OFF?

Go to Step 5

Go to Step 12

With the scan tool, observe the A/C Requested parameter in the instrument panel integration module (IPM) HVAC System Data list.

Does the scan tool display NO?

Go to Step 6

Go to Step 13

With a scan tool, observe the A/C Clutch (Desired) parameter in the BCM A/C Information List.

Does the scan tool display OFF?

Go to Step 15

Go to Step 14

1. Turn OFF the ignition.
2. Disconnect the A/C compressor clutch relay.
3. With the engine OFF, turn the ignition ON.

Does the A/C compressor clutch disengage?

Go to Step 8

Go to Step 9

Test the control circuit of the A/C compressor clutch relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 11

Test the voltage supply circuit of the A/C compressor clutch relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 10

Inspect for poor connections at the harness connector of the A/C compressor clutch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 17

Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 16

Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 18

Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 19

Inspect for poor connections at the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 20

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 21

Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

Go to Step 22

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Replace the A/C compressor clutch hub and plate. Refer to Compressor Clutch Plate and Hub Assembly Removal and Compressor Clutch Plate/Hub Assembly Install in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

Go to Step 22

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Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

Go to Step 22

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Important: Perform the recalibration procedure for the instrument panel integration module.

Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 22

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Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 22

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Important:  Perform the programming procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-3.8L.

Did you complete the replacement?

Go to Step 22

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2