GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: 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 review the HVAC operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms - HVAC Systems - Manual

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?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

With a scan tool, observe the A/C Request Signal parameter in the Engine Data 2 data list.

Does the scan tool indicate that the A/C Request Signal parameter is YES?

--

Go to Step 4

Go to Step 6

4

Test the A/C request signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the A/C high pressure switch.
  3. Start the engine.
  4. With a scan tool, observe the A/C Request Signal parameter.

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 switch side A/C compressor clutch relay terminals at the relay.

Does the resistance measurement equal the specified value?

Go to Step 8

Go to Step 10

8

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?

--

Go to Step 17

Go to Step 12

9

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 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 Connector Repairs .

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

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 Connector Repairs .

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 .

Did you complete the replacement?

--

Go to Step 17

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14

Replace the A/C compressor clutch. Refer to Air Conditioning Clutch Coil Replacement .

Did you complete the replacement?

--

Go to Step 17

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15

Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

--

Go to Step 17

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16

Important: Perform the programming procedure for the PCM.

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

Did you complete the replacement?

--

Go to Step 17

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17

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3