HVAC Compressor Clutch Does Not Disengage 6.6L, 8.1L
-
Placing the blower motor switch in the OFF position and the mode switch to the floor position, disables an A/C request.
-
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 in Wiring Systems | |||||
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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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/engine control module PCM/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 | ||||
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 in Wiring Systems. 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 in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 18 | -- | ||||
15 | Replace the A/C compressor. 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 programming procedure for the PCM/ECM. Replace the powertrain control module/engine control module 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 | ||||
HVAC Compressor Clutch Does Not Disengage 7.8L
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Placing the blower motor switch in the OFF position and the mode switch to the floor position, disables an A/C request.
-
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.
-
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 |
