GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Regal 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Functional Check

The blower delay timer is active when the system determines that the timer should emit heat in the Heat Auto modes.

The blower delay timer keeps the blower at the minimum speed. This low speed enables the engine coolant to warm up. If the ambient temperature is very cold, the delay can last for as long as 5 minutes.

Inspect for correct operation of the blower delay timer:

  1. Select the 16°C (60°F) setting in the HI mode.

    2. Verify that no delay occurs in system operation.

  2. Select a high temperature setting that is less than 32°C (90°F) in the AUTO mode.

    3. Verify that the following results occur:

    • The blower delay timer engages.
    • The blower remains at the minimum speed for no more than 5 minutes, until the engine coolant warms up.
    • At this point, the blower fan will be energized.

The blower delay timer does not function when the following conditions exist:

    • The system is in the HI or the DEFROST mode.
    • Cooling is required in AUTO.
    • The engine is warmed up.
        There is a slow airflow ramp up when the vehicle is very hot.

The control requires a constant battery positive feed. A constant battery positive feed maintains the memory function.

If the results that are described in this procedure do not occur, refer to Electrical Diagnosis for further diagnostic procedures.

Action

Normal Result(s)

Abnormal Result(s)

  1. Turn the ignition switch to the RUN position.
  2. Press the OFF button on the heater-A/C control.

The blower motor is OFF.

Refer to Blower Motor Always On .

  1. Press the blower control up button to increase speed until all the indicator LEDs are lit.
  2. Press the blower control DOWN button to decrease speed until all the indicator LEDs are off.

The blower motor increases to the maximum speed and then decreases to the minimum speed.

Refer to Blower Motor Inoperative at Any Speed .

  1. Turn the ignition switch to the RUN position.
  2. Press the AUTO button on the heater-A/C control.

The system switches to AUTO mode where the blower speed is controlled by the heater-A/C control.

Refer to Blower Motor Inoperative in Auto Mode .

Cycle the ignition switch through the following positions before you begin an inspection:

  1. The ON position
  2. The OFF position
  3. The ON position

If the system is operating correctly, the following actions will occur while you are cycling the ignition:

    • The heater air conditioning (A/C) temperature control lights.
    • The mode LEDs light.
    • The heater A/C temperature control and the mode LEDs repeat the same positions.

Leave the ignition in the ON position for at least 3 minutes. The 3 minutes will allow the blower delay to time out.

The compressor will not operate at ambient temperatures below 3°C (38°F).

Perform the following tests in order to inspect the HEAT functions. Ensure that the vehicle is in a garage at room temperature.

  1. Set the temperature to 15°C (60°F).
  2. Select the AUTO setting.
  3. Determine if the following functions occur while the system is in the 15°C (60°F) AUTO setting:
    4. • Cold air flows from the instrument panel (IP) outlets.
    • The blower operates at a high speed.
    • The noise level changes when in recirculation.
  4. Hold a small piece of paper against the inside air temperature sensor holes.

    5. If the sensor hose is aspirating correctly, the paper will remain against the sensor holes. If the hose is not aspirating correctly, the paper will fall to the floor.

  5. Set the temperature to 32°C (90°F).
  6. Select the AUTO setting.
  7. Determine if the following functions occur while the system is in the 32°C (90°F) AUTO setting:
    8. • Warm air flows from the heater outlet.
    • The blower operates at a high speed.
  8. Set the temperature to 32°C (90°F).
  9. Select the DEFROST setting.
  10. Determine if the following functions occur while the system is in the 32°C (90°F) DEFROST setting:
    11. • Warm air flows from the defroster outlets.
    • The blower operates at a high speed.
  11. Set the temperature to 24°C (75°F).
  12. Select the BI-LEVEL setting.
  13. Determine if the following functions occur while the system is in the 24°C (75°F) BI-LEVEL setting:
    14. • Air flows from the IP outlets and the heater outlets.
    • The blower speed slows down.
    • If the blower speed remains at a high speed, there may be a sensor condition.
    • Verify that the vehicle is at room temperature. If the vehicle is hot or cold, the system will run at high blower speed in this mode.