Test Description
The numbers below refer to the step numbers on the diagnostic table.
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These actions will disable the HVAC control module output to powertrain control module (PCM).
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This step checks the A/C Request Signal parameter to see if the PCM is interpreting an A/C request.
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Ensure that both A/C request signal circuits of the A/C high pressure switch are tested for listed conditions.
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The A/C Request Signal parameter is Yes. The A/C request signal circuits both are not shorted to ground. This step verifies that the A/C high pressure switch is not shorted internally to ground.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference : HVAC Schematics DEFINITION: The A/C compressor clutch will not disengage when an A/C request has been made, and a Powertrain DTC has not been set. | |||
1 | Did you perform the HVAC Diagnostic System Check? | 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 | |
With a scan tool, observe the A/C Request Signal parameter in the Powertrain data list. Does the scan tool indicate that the A/C Request Signal parameter is YES? | Go to Step 4 | Go to Step 6 | |
Test the A/C request signal circuit 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 17 | Go to Step 5 | |
Does the scan tool indicate that the A/C Request Signal 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 A/C compressor clutch relay terminals on the switch side. Does the resistance measurement show an open value? | Go to Step 8 | Go to Step 10 |
8 | 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 17 | Go to Step 12 |
9 | Test the supply voltage circuit of the A/C compressor clutch for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 14 |
10 | 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 17 | Go to Step 13 |
11 | Inspect for poor connections at the harness connector of the HVAC control module. 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 17 | Go to Step 15 |
12 | 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 17 | Go to Step 16 |
13 | 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 17 | -- |
14 | Replace the A/C compressor clutch. Refer to Compressor Clutch Plate/Hub Assembly Replacement in Heating, Ventilation, and Air Conditioning. Did you complete the replacement? | Go to Step 17 | -- |
15 |
Important: Perform the calibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 17 | -- |
16 |
Important: Program the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-4.8L, 5.3L, and 6.0L or to Powertrain Control Module Replacement in Engine Controls-8.1L. 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 |
