GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: HVAC Compressor Control Schematics .

DEFINITION: A/C compressor clutch will not disengage when no A/C request has been made and no Powertrain DTC has been set.

1

Did you review the HVAC operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms

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 in Wiring Systems

3

With a scan tool, observe the A/C request parameter in the Powertrain data list.

Does the scan tool indicate that the A/C request parameter is ON?

--

Go to Step 4

Go to Step 6

4

Test the A/C request signal 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 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 parameter.

Does the scan tool indicate that the A/C request parameter is ON?

--

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.

Does the resistance measurement equal the specified value?

OL

Go to Step 8

Go to Step 10

8

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 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 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 Connector Repairs in Wiring Systems.

--

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 Connector Repairs in Wiring Systems.

--

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 in Wiring Systems.

--

Go to Step 17

Go to Step 16

13

Replace the A/C compressor clutch relay.

Did you complete the replacement?

--

Go to Step 17

--

14

Replace the A/C compressor clutch. Refer to Compressor Clutch Plate and Hub Assembly Removal and Compressor Clutch Plate/Hub Assembly Install in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

--

Go to Step 17

--

15

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

Did you complete the replacement?

--

Go to Step 17

--

16

Important:: Perform the reprogramming procedure for the PCM.

Replace the Vehicle Control Module (VCM) or Powertrain Control Module (PCM). Refer to VCM Replacement/Programming in Engine Controls - 4.3L Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L.

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