HVAC Compressor Clutch Does Not Disengage 7.8L
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Placing the blower motor switch in the OFF position and the mode switch to the floor position, disables an A/C request.
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The A/C compressor clutch relay must be disconnected from previous step. The A/C compressor clutch control circuit is wired between the A/C high pressure switch and the A/C compressor clutch relay.
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The A/C compressor clutch control circuit is wired between the A/C high pressure switch and the A/C compressor clutch relay.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: A/C compressor clutch will not disengage when an A/C request has not been made and a Powertrain DTC has not been set. | ||||
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | |
Does the A/C compressor operate? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections | |
3 |
Does the A/C compressor clutch disengage? | Go to Step 4 | Go to Step 7 | |
4 |
Does the resistance measure near the specified value? | ∞ | Go to Step 5 | Go to Step 10 |
Does the test lamp illuminate? | Go to Step 6 | Go to Step 10 | ||
6 |
Does the test lamp illuminate? | Go to Step 8 | Go to Step 9 | |
7 | Test the A/C compressor clutch supply voltage circuit of the A/C compressor clutch for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
Test the A/C compressor clutch relay control circuit of the A/C compressor clutch relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 11 | |
9 | Test the A/C request signal circuit of the HVAC control assembly for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 12 |
10 | Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 13 |
11 | 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 . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
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 . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
13 | Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
14 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | Go to Step 17 | ||
16 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
17 | 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 6.6L, 8.1L
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Placing the blower motor switch in the OFF position and the mode switch to the floor position, disables an A/C request.
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There are 2 A/C request signal circuits of the A/C high pressure switch. Both must be tested or misdiagnosis could occur.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: A/C compressor clutch will not disengage when an A/C request has not been made and a powertrain DTC has not been set. | ||||||||
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | |||||
Does the A/C compressor operate? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections | |||||
3 |
Does the scan tool indicate that the A/C Request parameter is YES? | -- | Go to Step 4 | Go to Step 6 | ||||
Test both of the A/C request signal circuits of the A/C high pressure switch for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 5 | |||||
5 |
Does the scan tool indicate that the A/C Request parameter is YES? | -- | Go to Step 12 | Go to Step 11 | ||||
6 | Remove the A/C compressor clutch relay. Does the A/C compressor clutch turn OFF? | -- | Go to Step 7 | Go to Step 9 | ||||
7 | Measure the resistance between the switch side A/C compressor clutch relay terminals at the relay. Does the resistance measurement equal the specified value? | ∞ | Go to Step 8 | Go to Step 10 | ||||
8 | Test the A/C compressor clutch relay control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 12 | ||||
9 | Test the A/C compressor clutch supply voltage circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 13 | ||||
10 | Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 | ||||
11 | 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 . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 16 | ||||
12 | Inspect for poor connections at the harness connector of the powertrain control module (PCM)/engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 | ||||
13 | 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 . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 | ||||
14 | Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||
15 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement . 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 programming procedure for the PCM/ECM. Replace the PCM/ECM. Refer to one of the following procedures:
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 | ||||
