Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Placing the mode switch in any position other than OFF, along with placing the air temperature control 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.
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The HVAC control module (IPM) 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: A/C compressor clutch will not engage when an A/C request has been made and no Powertrain DTC has been set. | |||
1 | Did you perform the HVAC Diagnostic System Check? | Go to Step 2 | |
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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 |
Are the low and high side pressure values within the allowable limits for the recorded ambient air temperature, and within 103 kPa (15 psi) of each other? | Go to Step 4 | Go to Leak Testing in Heating, Ventilation and Air Conditioning |
4 |
Are the high side pressure values with 103 kpa (15 psi) of each other? | Go to Step 5 | Go to Step 20 |
Is the IPM inoperative? | Go to Step 19 | Go to Step 6 | |
6 |
Does the scan tool indicate that the Commanded A/C parameter is ON? | Go to Step 13 | Go to Step 7 |
7 | With a scan tool, observe the A/C Clutch (Desired) parameter in the DIM A/C Information list. Does the scan tool indicate that the A/C Clutch (Desired) parameter is ON? | Go to Step 8 | Go to Step 9 |
8 | With a scan tool, observe the A/C Clutch (Actual) parameter in the DIM A/C Information list. Does the scan tool indicate that the A/C Clutch (Actual) parameter is ON? | Go to Step 13 | Go to Step 33 |
9 | With a scan tool, observe the Control Head (Desired) parameter in the DIM A/C Information list. Does the scan tool indicate that the Control Head (Desired) parameter is ON? | Go to Step 10 | Go to Step 12 |
10 | With a scan tool, observe the Pressure Status parameter in the DIM A/C Information list. Does the scan tool indicate that the Pressure Status parameter is Normal? | Go to Step 11 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
11 | With a scan tool, observe the Temperature Status parameter in the DIM A/C Information list. Does the scan tool indicate that the Temperature Status parameter is OK? | Go to Step 30 | Go to Engine Overheating in Engine Cooling |
12 |
Does the scan tool indicate that the A/C Control Head (desired) parameter turn ON and OFF with each command? | Go to Step 30 | Go to Step 32 |
13 | 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 17 | Go to Step 14 |
14 |
Does the test lamp illuminate? | Go to Step 15 | Go to Step 27 |
15 |
Does the test lamp turn ON and OFF with each command? | Go to Step 29 | Go to Step 16 |
16 | Does the test lamp remain illuminated with each command? | Go to Step 23 | Go to Step 22 |
17 |
Does the test lamp illuminate? | Go to Step 18 | Go to Step 26 |
18 |
Does the A/C compressor clutch engage? | Go to Step 29 | Go to Step 24 |
19 | Test the ignition voltage circuit to the IPM 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 21 |
20 | Test the ground circuit of the A/C pressure sensor 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 28 |
21 | Test the ground circuit to the IPM 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 32 |
22 | 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 |
23 | 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 |
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 31 |
26 | 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 | -- |
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 harness connector of the A/C high pressure sensor. 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 |
29 | 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 36 |
30 | Inspect for poor connections at the DIM. 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 |
31 | 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 |
32 | Inspect for poor connections at the harness connector of the IPM. 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 |
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 DIM. Refer to Dash Integration Module Replacement in Body Control Systems. Did you complete the replacement? | Go to Step 40 | -- |
35 | Replace the A/C high pressure switch. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 40 | -- |
36 | Replace the A/C compressor clutch relay. Did you complete the replacement? | Go to Step 40 | -- |
37 | 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 40 | -- |
38 |
Important: Perform the recalibration procedure for the HVAC control module. Replace the IPM. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 40 | -- |
39 |
Important: Perform the setup procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-4.6L. 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 |
