GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

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 Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Start the engine.
  2. Place the blower motor switch in the OFF position.
  3. Place the A/C request switch in the OFF position.

Does the A/C compressor operate?

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Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

With a scan tool, observe the A/C Relay Command status in the powertrain control module (PCM) engine data 2 list.

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

--

Go to Step 4

Go to Step 5

4

With a scan tool, observe the A/C Request Signal parameter in the PCM engine data 2 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 compressor clutch relay control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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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 .

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 .

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 .

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 PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

12

Replace the A/C compressor clutch relay. Refer to Relay Replacement .

Did you complete the replacement?

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Go to Step 16

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13

Replace the A/C compressor clutch. Refer to Compressor Clutch Assembly Replacement .

Did you complete the replacement?

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Go to Step 16

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14

Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 16

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15

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

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