GM Service Manual Online
For 1990-2009 cars only

Step

Action

Normal Results

Abnormal Results

1

  1. Start the engine.
  2. Press the Heater A/C control OFF button.
  1. The outside temperature is displayed.
  2. The blower does not run.

DTC Table

2

  1. Press the AUTO button.
  2. Turn the temperature knob until the temperature displays 15°C (60°F).
  1. The blower runs at maximum speed.
  2. The air flows from the panel outlets.
  3. The A/C illuminates.
  4. The engine idle speed increases.
  5. The compressor turns ON.
  6. The air flow becomes cold.
  7. The engine coolant fan may operate

DTC Table

3

Turn the control knob to LOW SPEED

  1. Turn the knob to decrease the blower speed.
  2. The blower speed is displayed.
  3. The blower operates at the speed attained when the knob was released.

DTC Table

4

Turn the fan control knob to HIGH SPEED

  1. Turn the knob to increase the blower speed.
  2. The blower speed is displayed.
  3. The blower operates at the speed that was attained when the knob was released.

DTC Table

5

Press the button

  1. The engine idle speed decreases.
  2. The compressor turns off.
  3. The air flows from the panel outlets.
  4. The air may start to warm.

DTC Table

6

  1. Press the AUTO button.
  2. Change the temperature control until the temperature displays 32°C (90°F).

The air flows from the floor outlets.

The air flow becomes warm.

Air Temperature Control Inoperative

7

Change the temperature control until the temperature displays 24°C (75°F).

  1. The temperature display drops one degree at a time and stops at 24°C (75°F).
  2. The blower speed reduces as the temperature approaches 24°C (75°F).
  3. The A/C system maintains the temperature at approximately 24°C (75°F).
  4. The air flows from the panel and floor outlets when the temperature is near 24°C (75°F) and the control selector is put in the BI-LEVEL position.

Air Temperature Control Inoperative

8

Place the mode selector in the DEF position.

The air flows from the windshield outlets.

Defrost Air Inoperative

9

Place the mode selector in the DEFOG position.

The air flows from the panel, floor and windshield outlets.

Defrost Air Inoperative

10

Place the mode selector in the UPPER position.

The air flows from the panel outlets.

Instrument Panel Outlets Inoperative

11

Place the mode selector in the LOWER position.

The air flows from the floor outlets.

Heated Air Inoperative

12

Place the mode selector in the VENT position.

Outside air flows from the panel outlets.

Air Recirculation Always On

13

Place the mode selector in the RECIRC/MAX position.

Inside air is recirculated through the panel and floor outlets.

Air Recirculation Inoperative