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?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Start the engine.
  2. Place the blower motor switch in the OFF position.
  3. Place the air conditioning (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 Relay Commanded parameter in the Powertrain control module data list 2.

Does the scan tool indicate that the A/C Relay Command parameter is OFF?

--

Go to Step 4

Go to Step 6

4

With a scan tool, observe the A/C Request parameter in the body control module (BCM) data list.

Does the scan tool indicate that the A/C Request parameter is No?

--

Go to Step 5

Go to Step 14

5

Test the control circuit of the A/C compressor clutch relay 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 20

Go to Step 7

6

  1. Start the engine.
  2. Place the A/C switch in the OFF position.
  3. Measure the voltage on the request circuit at the BCM to a good ground.

Does the voltage measure near the specified value?

12 V

Go to Step 9

Go to Step 13

7

Remove the A/C compressor clutch relay.

Does the A/C compressor clutch turn OFF?

--

Go to Step 10

Go to Step 8

8

Test the A/C compressor clutch voltage supply circuit, at the A/C compressor clutch 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 20

Go to Step 11

9

Test the A/C request signal 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 20

Go to Step 12

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.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 15

11

Inspect for poor connections at the harness connector of the A/C compressor clutch. 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 20

Go to Step 16

12

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 17

13

Inspect for poor connections at the BCM. 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 20

Go to Step 18

14

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 20

Go to Step 19

15

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 20

--

16

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

Did you complete the replacement?

--

Go to Step 20

--

17

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

Did you complete the replacement?

--

Go to Step 20

--

18

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

19

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2