HVAC Compressor Clutch Does Not Engage CJ3
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Placing the mode switch in any position other than OFF, along with placing the air temperature switch in a cold setting, activates A/C operation. For the purpose of this and future steps where A/C operation is necessary, bi-level mode is used for consistent testing.
-
The HVAC control module is inoperative when the module does not respond to any operator control requests to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.
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 | |
Is the engine coolant temperature indicator illuminated? | Go to Engine Coolant Temperature Indicator Always On in Engine Cooling | Go to Step 3 | |
|
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 4 | |
4 |
Are the pressure values within the specifications for the ambient air temperature, and within 103 kPa (15 psi) of each other? | Go to Step 5 | Go to Leak Testing in Heating, Ventilation and Air Conditioning |
Is the HVAC control module inoperative? | Go to Step 16 | Go to Step 6 | |
6 |
Does the scan tool indicate that the A/C Request Signal parameter is YES? | Go to Step 10 | Go to Step 7 |
7 | Does the A/C request indicator illuminate? | Go to Step 9 | Go to Step 8 |
8 |
Important: The blower motor must be in the ON position for this step.
Did you find and correct the condition? | Go to Step 32 | Go to Step 26 |
9 |
Did you find and correct the condition? | Go to Step 32 | Go to Step 27 |
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 14 | Go to Step 11 |
11 |
Does the test lamp illuminate? | Go to Step 12 | Go to Step 22 |
12 |
Does the test lamp turn ON and OFF with each command? | Go to Step 23 | Go to Step 13 |
13 | Does the test lamp remain illuminated with each command? | Go to Step 19 | Go to Step 18 |
14 |
Does the test lamp illuminate? | Go to Step 15 | Go to Step 23 |
15 |
Does the A/C compressor clutch engage? | Go to Step 24 | Go to Step 20 |
16 | Test the ignition-3 voltage circuit of the HVAC control module 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 32 | Go to Step 17 |
17 | Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 32 | Go to Step 26 |
18 | 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 32 | Go to Step 27 |
19 | 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 32 | Go to Step 27 |
20 | 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 32 | Go to Step 21 |
21 | 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 32 | Go to Step 25 |
22 | 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 32 | -- |
23 | 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 32 | -- |
24 | 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 32 | Go to Step 28 |
25 | 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 31 | Go to Step 29 |
26 | 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 32 | Go to Step 30 |
27 | 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 32 | Go to Step 31 |
28 | 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 32 | -- |
29 | Replace the A/C compressor clutch coil. Refer to A 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 32 | -- |
30 | Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 32 | -- |
31 |
Important: Perform the programming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-2.5L and 3.0L Did you complete the replacement? | Go to Step 32 | -- |
32 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 4 |
HVAC Compressor Clutch Does Not Engage CJ4
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Placing the mode switch in any position other than OFF, along with placing the air temperature switch in a cold setting, activates A/C operation. For the purpose of this and future steps where A/C operation is necessary, bi-level mode is used for consistent testing.
-
The HVAC control module is inoperative when the module does not respond to any operator control requests to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.
-
The auxiliary HVAC control assembly is inoperative when the module does not respond to any operator control requests to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.
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 | |
Is the engine coolant temperature indicator illuminated? | Go to Engine Coolant Temperature Indicator Always On in Engine Cooling | Go to Step 3 | |
|
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 4 | |
4 |
Are the pressure values within the specifications for the ambient air temperature, and within 103 kPa (15 psi) of each other? | Go to Step 5 | Go to Leak Testing in Heating, Ventilation and Air Conditioning |
Is the HVAC control module inoperative? | Go to Step 17 | Go to Step 6 | |
Is the auxiliary HVAC control assembly inoperative? | Go to Step 19 | Go to Step 7 | |
7 | Test the A/C request circuit of the auxiliary HVAC control assembly for a short to ground or voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Does the request circuit have a short to ground or voltage, high resistance, or an open? | Go to Step 27 | Go to Step 8 |
8 | With a DVOM measure the voltage from the A/C request circuit of the auxiliary HVAC control assembly to a good ground. Does the voltage change when the rear A/C request switch is pressed? | Go to Step 9 | Go to Step 31 |
9 |
Does the scan tool indicate that the A/C Request Signal parameter is YES? | Go to Step 10 | Go to Step 30 |
10 | With a scan tool, observe the A/C Relay Command status in the Engine Data-2 list. Does the scan tool indicate that the A/C Relay Command status is ON? | Go to Step 11 | Go to Step 32 |
11 | 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 15 | Go to Step 12 |
12 |
Does the test lamp illuminate? | Go to Step 13 | Go to Step 26 |
13 |
Does the test lamp turn ON and OFF with each command? | Go to Step 28 | Go to Step 14 |
14 | Does the test lamp remain illuminated with each command? | Go to Step 22 | Go to Step 21 |
15 |
Does the test lamp illuminate? | Go to Step 16 | Go to Step 25 |
16 |
Does the A/C compressor clutch engage? | Go to Step 28 | Go to Step 23 |
17 | Test the ignition-3 voltage circuit of the HVAC control module 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 38 | Go to Step 18 |
18 | Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 38 | Go to Step 30 |
19 | Test the ignition-3 voltage circuit of the auxiliary 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 38 | Go to Step 20 |
20 | Test the ground circuit of the auxiliary 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 38 | Go to Step 31 |
21 | 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 38 | Go to Step 32 |
22 | 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 38 | Go to Step 32 |
23 | 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 38 | Go to Step 24 |
24 | 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 38 | Go to Step 29 |
25 | 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 38 | -- |
26 | 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 38 | -- |
27 | Repair the A/C request circuit of the auxiliary HVAC control assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 38 | -- |
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 38 | Go to Step 33 |
29 | 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 38 | Go to Step 34 |
30 | 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 38 | Go to Step 35 |
31 | Inspect for poor connections at the harness connector of the auxiliary 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 38 | Go to Step 36 |
32 | 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 38 | Go to Step 37 |
33 | 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 38 | -- |
34 | Replace the A/C compressor clutch coil. Refer to A 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 38 | -- |
35 | Replace the front HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 38 | -- |
36 | Replace the auxiliary HVAC control assembly. Refer to Auxiliary Heater and Air Conditioning Control Replacement . Did you complete the replacement? | Go to Step 38 | -- |
37 |
Important: Perform the programming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-2.5L and 3.0L Did you complete the replacement? | Go to Step 38 | -- |
38 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 4 |
