GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC Suburban - 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. Rotate the front blower switch through all fan speeds:
    3. • Low
    • Med 1
    • Med 2
    • High

The blower motor runs in all positions.

2

Turn the front blower switch to the OFF position.

Blower motor stops running

Blower Motor Always On

3

Rotate the auxiliary HVAC control module, Front through all fan speeds:

    • Low
    • Med
    • High
  1. Turn the auxiliary HVAC control module, front to the rear position.
  2. Rotate the auxiliary HVAC control module, rear through all fan speeds:
    3. • Low
    • Med
    • High

The auxiliary blower motor runs in all positions.

4

Turn the auxiliary HVAC switch to the OFF position.

Auxiliary blower motor stops running

Auxiliary Blower Motor Always On

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