GM Service Manual Online
For 1990-2009 cars only

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

  1. Start the vehicle.
  2. Ensure that the A/C system is in the OFF position.
  3. Turn the mode switch to the DEFOG position.
  4. Turn the blower switch from the LOW to the HIGH position.
  5. Turn the blower switch from the HIGH to the OFF position.
  1. Air discharge at IP outlets will increase with rotation of the blower switch.
  2. The blower motor shuts OFF.

2

  1. Start the vehicle.
  2. Turn the blower switch to the LOW position
  3. Press the A/C switch to select ON.

A/C compressor clutch engages.

VDOT Air Conditioning (A/C) System Diagnosis

3

Press the A/C switch to select OFF.

A/C compressor clutch disengages.

VDOT Air Conditioning (A/C) System Diagnosis

4

  1. Turn the blower to the high position.
  2. Rotate the mode switch through all mode positions. Allow a momentary pause at each position.

Air is discharged at each requested location.

HVAC Air Delivery System Check

5

No abnormal results where found while performing the System Check.

The system is OK.

VDOT Air Conditioning (A/C) System Diagnosis

* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.