For 1990-2009 cars

## HVAC Compressor Clutch Does Not Disengage L81

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The A/C compressor clutch will not disengage when an A/C request has not been made and a Engine Control DTC has not been set.
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - HVAC Systems - Manual
2 |

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

3 | With a scan tool, observe the A/C request signal parameter in the Engine Control Module, General Info Outputs data list. Does the scan tool indicate that the A/C request signal parameter is YES? | -- | Go to Step 4 | Go to Step 6
4 | Test the A/C request signal circuit 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 18 | Go to Step 5
5 |

1. Turn OFF the ignition.
2. Disconnect the A/C refrigerant pressure sensor.
3. Start the engine.
4. With a scan tool, observe the A/C request signal parameter.

Does the scan tool indicate that the A/C request signal parameter is YES?

--

Go to Step 13

Go to Step 12

6 | With a scan tool, command the A/C compressor clutch relay ON and OFF. Does the A/C compressor clutch relay turn ON and OFF with each command? | -- | Go to Step 7 | Go to Step 9
7 | Remove the A/C compressor clutch relay. Is the A/C compressor ON? | -- | Go to Step 10 | Go to Step 8
8 | Measure the resistance between the switch side A/C compressor clutch relay terminals. Does the resistance measurement equal the specified value? | ∞ | Go to Step 9 | Go to Step 11
9 | Test the A/C clutch relay control circuit 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 18 | Go to Step 13
10 | Test the A/C compressor clutch supply voltage circuit 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 18 | Go to Step 15
11 | 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 18 | Go to Step 14
12 | Inspect for poor connections at the harness connector of the hvac control assembly. 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 18 | Go to Step 16
13 | Inspect for poor connections at the harness connector of the engine control module (ECM). 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 18 | Go to Step 17
14 | Replace the A/C compressor clutch relay. Did you complete the replacement? | -- | Go to Step 18 | --
15 | Replace the A/C compressor clutch. Refer to Air Conditioning Compressor Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | -- | Go to Step 18 | --
16 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 18 | --
17 | Important:: Perform the reprogramming procedure for the ECM. Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls - 3.0L. Did you complete the replacement? | -- | Go to Step 18 | --
18 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 3

## HVAC Compressor Clutch Does Not Disengage L61

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The A/C compressor clutch will not disengage when an A/C request has not been made and a PowertrainControl DTC has not been set.
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - HVAC Systems - Manual
2 |

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

3 | With a scan tool, observe the A/C request signal parameter in the Powertrain Control Module, General Info Outputs data list. Does the scan tool indicate that the A/C request signal parameter is YES? | -- | Go to Step 4 | Go to Step 6
4 | Test the A/C request signal circuit 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 18 | Go to Step 5
5 |

1. Turn OFF the ignition.
2. Disconnect the A/C refrigerant pressure sensor.
3. Start the engine.
4. With a scan tool, observe the A/C request signal parameter.

Does the scan tool indicate that the A/C request signal parameter is YES?

--

Go to Step 13

Go to Step 12

6 | With a scan tool, command the A/C compressor clutch relay ON and OFF. Does the A/C compressor clutch relay turn ON and OFF with each command? | -- | Go to Step 7 | Go to Step 9
7 | Remove the A/C compressor clutch relay. Is the A/C compressor ON? | -- | Go to Step 10 | Go to Step 8
8 | Measure the resistance between the switch side A/C compressor clutch relay terminals. Does the resistance measurement equal the specified value? | ∞ | Go to Step 9 | Go to Step 11
9 | Test the A/C clutch relay control circuit 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 18 | Go to Step 13
10 | Test the A/C compressor clutch supply voltage circuit 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 18 | Go to Step 15
11 | 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 18 | Go to Step 14
12 | Inspect for poor connections at the harness connector of the hvac control assembly. 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 18 | Go to Step 16
13 | Inspect for poor connections at the harness connector of the powertrain control module (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 18 | Go to Step 17
14 | Replace the A/C compressor clutch relay. Did you complete the replacement? | -- | Go to Step 18 | --
15 | Replace the A/C compressor clutch. Refer to Air Conditioning Compressor Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | -- | Go to Step 18 | --
16 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement Did you complete the replacement? | -- | Go to Step 18 | --
17 | Important:: Perform the reprogramming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 2.2L. Did you complete the replacement? | -- | Go to Step 18 | --
18 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 3