GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

1

Did you review the Air Delivery Description and Operation and the Air Temperature Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

  1. Star the engine.
  2. Turn the A/C switch to the OFF position.
  3. Turn the blower switch to any position except OFF.

Does the A/C compressor clutch disengage?

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

Go to Step 3

3

Remove the A/C MG relay from fuse and relay block 2.

Does the A/C compressor clutch disengage?

Go to Step 5

Go to Step 4

4

Repair the short to voltage in the A/C compressor clutch supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

--

5

Test the A/C MG relay for continuity between terminals 3 and  5. Refer to

Fuse and Relay Block 2


Object Number: 334466  Size: SF
(1)A/C MG Relay
(2)A/C FAN No.3 Relay
(3)A/C FAN No.3 Relay
(4)Dimmer Relay
(5)CDS Fuse 30A
(6)HEAD (LH-LWR) Fuse 10A
(7)HEAD (RH-LWR) Fuse 10A
(8)DRL Fuse 7.5A
(9)Fuse and Relay Block 2
in Wiring Systems.

Does continuity exist?

Go to Step 11

Go to Step 6

6

  1. Install the A/C MG relay.
  2. Disconnect the A/C switch.

Does the A/C compressor clutch disengage?

Go to Step 12

Go to Step 7

7

  1. Connect the A/C switch.
  2. Disconnect the A/C compressor control module.

Does the A/C compressor clutch disengage?

Go to Step 9

Go to Step 8

8

Repair the short to ground in the A/C MG relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

--

9

Test for a short to voltage in the A/C compressor control module supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

10

Replace the A/C compressor control module. Refer to Air Conditioning (A/C) Compressor Control Module Replacement .

Did you complete the replacement?

Go to Step 13

--

11

Replace the MG relay. Refer to Compressor Relay Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the A/C switch. Refer to Control Assembly Replacement .

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3