HVAC Compressor Clutch Does Not Engage w/6.5L (L65)
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The HVAC control assembly is inoperative if the module does not respond to an operator request.
-
Ensure to test all A/C request circuits that connect to the A/C high pressure switch and the A/C low pressure switch.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference : HVAC Schematics DEFINITION: The A/C compressor clutch will not engage when an A/C request has been made and a Powertrain DTC has not been set. | |||
1 | Did you perform the HVAC Systems Check? | Go to Step 2 | |
2 |
Important: The ambient air temperature must be above 3°C (38°F).
Does the A/C compressor operate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
3 | Perform the A/C performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning. Did the A/C system pass the A/C performance test? | Go to Step 4 | Go to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning |
Is the HVAC control assembly inoperative? | Go to Step 6 | 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 8 |
6 | Test the voltage supply circuits to the HVAC control assembly for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 7 |
7 | Test the ground circuit to the HVAC control assembly for an high resistance, or for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 27 |
8 |
Does the scan tool indicate that the A/C Request parameter is YES? | Go to Step 28 | Go to Step 9 |
9 |
Does the scan tool indicate that the A/C Request parameter is YES? | Go to Step 25 | Go to Step 10 |
Did you find and correct the condition? | Go to Step 36 | Go to Step 11 | |
11 | Measure the voltage from the A/C request circuit at the PCM. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Is the voltage measurement near battery voltage? | Go to Step 29 | Go to Step 27 |
12 | With a scan tool, command the A/C compressor clutch relay ON and OFF. Does the relay of the A/C compressor clutch turn ON and OFF with each command? | Go to Step 13 | Go to Step 15 |
13 |
Does the test lamp illuminate? | Go to Step 14 | Go to Step 23 |
14 |
Does the A/C compressor clutch engage? | Go to Step 24 | Go to Step 18 |
15 |
Does the test lamp illuminate? | Go to Step 16 | Go to Step 22 |
16 |
Does the test lamp turn ON and OFF with each command? | Go to Step 24 | Go to Step 17 |
17 | Does the test lamp remain illuminated with each command? | Go to Step 20 | Go to Step 21 |
18 | Test the supply voltage circuit at the A/C compressor clutch for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 19 |
19 | Test the ground circuit of the A/C compressor clutch for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 26 |
20 | Test the control circuit of the A/C compressor clutch relay for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 29 |
21 | Test the control circuit of the A/C compressor clutch relay for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 29 |
22 | Repair the coil side of the voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 36 | -- |
23 | Repair the switch side of the voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 36 | -- |
24 | Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 30 |
25 | Inspect for poor connections at the harness connector of the A/C low pressure switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 31 |
26 | Inspect for poor connections at the harness connector of the A/C compressor clutch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 33 |
27 | Inspect for poor connections at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 34 |
28 | Inspect for poor connections at the harness connector of the A/C high pressure switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 32 |
29 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 35 |
30 | 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 36 | -- |
31 | Replace the A/C low pressure switch. Refer to Compressor Control Switches Removal and to Compressor Control Switches Install in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 36 | -- |
32 | Replace the A/C high pressure switch. Refer to Air Conditioning (A/C) High Pressure Switch Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 36 | -- |
33 | Replace the A/C compressor clutch coil. Refer to Air Conditioning Clutch Coil Removal and to Air Conditioning Clutch Coil Installation in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 36 | -- |
34 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | Go to Step 36 | -- |
35 |
Important: Program the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 6.5L. Did you complete the replacement? | Go to Step 36 | -- |
36 | 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 Engage w/8.1L (L18)
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The HVAC control assembly is inoperative when the module does not respond to any operator control requests.
-
When the blower motor is in the OFF position, a voltage is applied to the OFF blower motor control circuit. The A/C system will not operate if a voltage is applied to the OFF blower motor control circuit.
-
Ensure to test both A/C request circuits that connect to the A/C high pressure switch.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: HVAC Schematics DEFINITION: The A/C compressor clutch will not engage when an A/C request has 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 | |
2 |
Important: The ambient air temperature must be above 3°C (38°F).
Does the A/C compressor operate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
3 | Perform the A/C performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning. Did the A/C system pass the A/C performance test? | Go to Step 4 | Go to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning |
Is the HVAC control assembly inoperative? | Go to Step 19 | Go to Step 5 | |
5 |
Does the scan tool indicate that the A/C Request parameter is YES? | Go to Step 8 | Go to Step 6 |
6 | Does the A/C request indicator illuminate? | Go to Step 7 | Go to Step 21 |
7 |
Important: Ensure that the blower motor switch is not in the OFF position during this step.
Does the scan tool indicate that the A/C Request parameter is ON? | Go to Step 32 | Go to Step 26 |
8 | Does the scan tool indicate the A/C Compressor Cycling parameter is 1=Normal? | Go to Step 10 | Go to Step 9 |
9 |
Does the scan tool indicate the A/C Compressor Cycling parameter is 1=Normal? | Go to Step 29 | Go to Step 22 |
10 | 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 16 | Go to Step 11 |
11 |
Does the test lamp illuminate? | Go to Step 12 | Go to Step 27 |
12 |
Does the test lamp turn ON and OFF with each command? | Go to Step 28 | Go to Step 13 |
13 | Does the test lamp remain illuminated with each command? | Go to Step 15 | Go to Step 14 |
14 | Test the control circuit of the A/C compressor clutch relay for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 33 |
15 | 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 40 | Go to Step 33 |
16 |
Does the test lamp illuminate? | Go to Step 17 | Go to Step 18 |
17 |
Does the A/C compressor clutch engage? | Go to Step 28 | Go to Step 24 |
18 | Repair the switch side voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 40 | -- |
19 | Test the ignition 3 voltage circuit of the HVAC control assembly for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 20 |
20 | Test the ground circuit of the HVAC control assembly for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 31 |
|
Important: Ensure that the blower motor switch is not in the OFF position during this step. Test the OFF blower motor control 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 40 | Go to Step 31 | |
22 | Test the A/C low pressure switch signal circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 23 |
23 | Test the ground circuit of the A/C low pressure switch for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 33 |
24 | Test the A/C compressor clutch supply voltage circuit at the A/C compressor clutch for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 25 |
25 | Test the ground circuit of the A/C compressor clutch for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 40 | Go to Step 30 |
Did you find and correct the condition? | Go to Step 40 | Go to Step 33 | |
27 | Repair the coil side voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 40 | -- |
28 | 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 40 | Go to Step 34 |
29 | Inspect for poor connections at the harness connector of the A/C low pressure switch. 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 40 | Go to Step 35 |
30 | 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 40 | Go to Step 37 |
31 | 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 40 | Go to Step 38 |
32 | Inspect for poor connections at the harness connector of the A/C high pressure switch. 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 40 | Go to Step 36 |
33 | 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 40 | Go to Step 39 |
34 | Replace the A/C compressor clutch relay. Did you complete the replacement? | Go to Step 40 | -- |
35 | Replace the A/C low pressure switch. Refer to Compressor Control Switches Removal and Compressor Control Switches Install in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 40 | -- |
36 | Replace the A/C high pressure switch. Refer to Air Conditioning (A/C) High Pressure Switch Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 40 | -- |
37 | Replace the A/C compressor clutch coil. Refer to Air Conditioning Clutch Coil Removal and Air Conditioning Clutch Coil Installation in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 40 | -- |
38 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | Go to Step 40 | -- |
39 |
Important: Perform the programming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 8.1L. Did you complete the replacement? | Go to Step 40 | -- |
40 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
