This work for 1998 Buick Century 3.1L SFI OHV 6cyl; the blower motor is a variable speed motor. The higher the voltage
applied to the motor, the faster the speed. Depending on the HVAC
(Heater Ventilation Air Conditioning) option installed in the vehicle,
blower speed control could be through a set of resistors or through a
solid-state blower motor control module.
In general, this system is reliable. Because so many of the control
operations are electronic, special diagnostic equipment really should be
used for system diagnostics and check-out. An authorized technician
using a scan tool can most quickly locate HVAC problems.
Fig. Typical behind-the-instrument panel view of HVAC related
components. Depending on the HVAC option, not all components are used on
all vehicles (click for zoom)
Fig. Typical HVAC operation schematic
An inoperative blower motor could be caused by the following:
* Blown fuse(s). The fuse should be replaced. There may be both a
LOW BLOWER and HIGH BLOWER fuse. Some models may also call it the HVAC
fuse. Even the RADIO fuse is used in some applications. Check them all.
If a fuse is blown there may be a short to ground in one of the power
* Open Circuit. Check the circuit between the ignition switch and
the blower motor, and the blower motor ground circuit. Repair as
* Faulty blower switch. A faulty blower switch should be replaced.
* Most heater blower circuits also include a blower motor relay
(look in the underdash convenience center), as well as a blow motor
resistor. These items should be checked especially if the blower runs in
one or two speeds, but not all speeds selected.
REMOVAL & INSTALLATION
Disconnect the negative battery cable.
The blower motor is located on the passenger side of the vehicle,
under the instrument panel. Remove the right side sound insulator (trim
panel) by removing the retainers and disconnecting the courtesy lamp.
Detach the blower motor electrical connector. Some applications may have cooling hose to the motor which should be disconnected.
Fig. Blower motor and fan assembly removal
Unfasten the blower motor mounting screws, then remove the blower motor from the vehicle.
If the blower motor fan (also called a 'squirrel cage') must be replaced, use the following procedure:
Do not hammer on the motor to remove or install the fan. Do not
apply force to the motor housing to seat the fan on the motor, or
motor/shaft bearing damage could result. Do not apply pressure to the
fan rim. Be sure the correct replacement part is used.
Remove the metal star clip retaining the fan cage to the motor shaft.
Remove the fan by pulling straight out.
If removed, install the blower motor fan, as follows:
Install the replacement fan cage onto the motor shaft.
Adjust the fan cage to get a clearance of 0.30 inch (7.5mm) to the motor mount plate.
Install the remaining components in the reverse of the removal
procedure. Make sure the electrical connection is secure. Tighten the
motor screws to 14 ft. lbs. (20 Nm).
Connect the negative battery cable, then test the blower motor for proper operations
I hope this helps (remember to rate and comment this answer).