How to Change the Blower Motor on a 99 Grand Prix

by Don Bowman

    The 1999 Pontiac Grand Prix has a variable-speed fan motor. The blower motor speed is regulated by a module in cars with automatic climate control, and by a resistor in cars without. The resistor or module steps the voltage down, thus controlling low and medium fan speeds. High speed removes the resistor from the circuit and the blower motor relay energizes. This directs full battery voltage to the fan motor. The blower motor on a 1999 Grand Prix is located under the dash on the passenger side, above the sound insulator panel.

    Items you will need

    • Phillips screwdriver
    • 1/4-inch-drive ratchet
    • 1/4-inch-drive, 5.5 mm socket
    • 1/4-inch-drive torque wrench calibrated in inch-pounds
    • Small flat-head screwdriver

    Removal

    Step 1

    Look under the passenger side of the instrument panel and you will see a sound insulator, or trim panel, covering the lower section of the dash. Remove the Phillips screws, lower the sound insulator, and disconnect the courtesy light.

    Step 2

    Remove the two screws in the rear of the convenience center using the Phillips screwdriver. Loosen the front screw and slide the convenience center out. Grab the carpet at the top of the cowl and pull it toward the passenger seat just enough to allow the blower motor squirrel cage to clear the HVAC housing.

    Step 3

    Look up under the dash and you will see the bottom of the blower motor. It’s secured to the heater and air conditioner housing, or HVAC, with 5.5 mm screws. Remove the fan motor electrical connector by using the small flat-head screwdriver to lift the locking tab. Disconnect the harness retainer clip.

    Step 4

    Disconnect the small rubber cooling hose plugged into the bottom side of the fan motor, if one is present. Some applications use them, while others on the Grand Prix do not. Remove the 5.5 mm screws in the flange that secure the fan motor to the HVAC housing with the use of a ratchet and socket.

    Step 5

    Drop the fan motor straight down, allowing the squirrel cage enough room to exit the HVAC housing. Pay attention to the electrical plug orientation so you can install the motor with the plug in the same location.

    Installation

    Step 1

    Hold the blower motor with the electrical connection in the correct location. Lift the blower motor straight up into the HVAC housing and align the screw holes.

    Step 2

    Install the 5.5 mm screws in the blower motor flange and torque them with the torque wrench to 14 foot-pounds. Install the cooling hose by pushing it into the hole on the bottom side of the motor. Notice that the hose end on the blower side has a groove similar to a bushing. Seat the groove in the blower motor housing.

    Step 3

    Plug the electrical harness connector into the blower motor. Install the harness support clip. Push the carpet back into place.

    Step 4

    Install the convenience center and the under-dash sound insulator panel. Install the courtesy light. Test the fan motor for proper operation.

    Tip

    • There are several possible causes for an inoperative blower motor. A blown fuse to the blower motor indicates a short to ground in one of the circuits supplying power. There may be both high and low blower fuses, depending on the type of air conditioning system. Replace them with the same amperage fuses.
    • An open circuit between the ignition switch and the blower motor or its ground circuit will result in an inoperative blower motor.
    • A faulty blower switch on the dash fan speed control may also result in an inoperative blower motor.
    • A failed blower motor resistor, or module in the case of automatic climate control, will allow the fan motor to operate on high speed only.

    References

    • Chilton's; 1999 Pontiac Grand Prix; Blower Motor