GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Safari - 4WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 HVAC Blower Controls System Check

Step

Action

Normal Result(s)

Abnormal Result(s)

1
  1. Turn the ignition switch to the RUN position.
  2. Set the Heater-A/C Control to the VENT position.
  3. Set the Blower switch to the OFF position.

The blower motor is off.

Blower Motor Always On .

2
  1. Turn the temperature control knob to the extreme hot position.
  2. Turn the blower motor switch to the following positions:
    3. • LO
    • M1
    • M2
    • HI

The blower motor operates at increasingly faster speeds.
    •  Heating Insufficient .

3

The following procedure only applies if the vehicle is equipped with rear HVAC controls.

  1. Turn the ignition switch to the RUN position.
  2. Move the temperature control knob to the extreme hot position.
  3. Move the rear heater switch to the following positions in the following order:
    4. 3.1. LOW
    3.2. MED
    3.3. HIGH
    3.4. LOW
    • The rear blower motor speed will increase at each speed level when the blower speed selector switch moves toward the HIGH position.
    • The blower motor speed will decrease at each speed level as the switch moves toward the LOW position.
    • The air should be warm if the vehicle is at operating temperature.