GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The 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 perform the HVAC Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Start the engine.
  2. Turn OFF the HVAC controls.

Does the A/C compressor operate?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

With a scan tool, observe the A/C Relay Command Parameter in the Powertrain data list.

Does the scan tool indicate that the A/C Relay Command Parameter is ON?

--

Go to Step 4

Go to Step 5

4

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 10

Go to Step 11

5

Remove the A/C compressor clutch relay.

Does the A/C compressor clutch turn OFF?

--

Go to Step 6

Go to Step 8

6

Measure the resistance between the switch side A/C compressor clutch relay terminals.

Does the resistance measurement equal the specified value?

Go to Step 7

Go to Step 9

7

Test the A/C 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 16

Go to Step 11

8

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 16

Go to Step 13

9

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 16

Go to Step 12

10

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 16

Go to Step 14

11

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 16

Go to Step 15

12

Replace the A/C compressor clutch relay.

Did you complete the replacement?

--

Go to Step 16

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13

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 16

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14

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

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15

Important: Perform the reprogramming procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-3.4L.

Did you complete the replacement?

--

Go to Step 16

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16

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3