DESCRIPTION & OPERATION
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.
Battery voltage to the blower motor is supplied by the heater & A/C control by way of the blower resistor (or blower motor control module). At low and medium speeds, the voltage is stepped down by the blower motor resistors. At high speed, the blower motor relay is energized, removing the blower motor resistors from the circuit. Battery voltage is then applied directly to the blower motor through the relay. The motor will then run at maximum speed.
Several types of HVAC systems were available on these vehicles, from manual to fully automatic electronic control. The blower motor speed can be adjusted manually by pushing the fan switch up or down or automatically by placing the heater & A/C control in the AUTO mode.
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.
An inoperative blower motor could be caused by the following:
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.
- 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:
- 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