GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn the ignition OFF.
  2. Inspect the A/C compressor for free rotation operation.
  3. Start the engine.
  4. Place the mode switch to the Vent position.
  5. Place the blower motor switch in the maximum speed position.
  6. Place the air temperature switch in the coldest position.

Does the A/C compressor operate?

Go to Step 3

Go to HVAC Compressor Clutch Does Not Engage

3

  1. Turn the ignition ON, with the engine OFF.
  2. Place the blower switch in each speed position.

Does the blower motor operate in any of the speed positions?

Go to Step 4

Go to Blower Motor Inoperative

4

Does the blower motor operate at the desired speeds?

Go to Step 5

Go to Blower Motor Malfunction

5

  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Lower the glove box off its upper attachments.
  4. Observe the recirculation door.
  5. Place the recirculation switch in the ON position.

Does the recirculation door move to the recirculation position?

Go to Step 6

Go to Air Recirculation Malfunction

6

When the A/C is ON, does the customer concern occur?

Go to Step 7

Go to Step 8

7

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test .

Did you find and correct the condition?

Go to Step 9

Go to Step 8

8

Inspect the air temperature door and linkage for the following conditions:

    • High effort to operate air temperature door
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within its full range of motion
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature door

Did you find and correct the condition?

Go to Step 9

Go to High or Low Temperature Control Effort

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2