Instructions for Replacement Furnace Blower Motors

Testing

• Turn off the power to the furnace before you start working, then begin your inspection by trying to spin the blower by hand. If it won’t spin, try adding a few drops of oil to the oil ports. If it still doesn’t spin after oiling, or if your blower is sealed and doesn’t have oil ports, you will need to replace the motor.

More Tests

• If the blower spins, continue your inspection by checking for loose connections. Make sure the motor is cool first. Use a multimeter to check the run capacitor. If the reading you get is more than 6 percent lower than the rating on the capacitor, replace it. When you’re finished, test the blower by turning the power to the furnace back on. You should also turn the fan on at the thermostat. If the blower still doesn’t start, you will need to replace the motor. Don’t forget to turn the power back off.

Removal

• Note the colors of the motor wires and where each one is connected before you start disconnecting them. Remove the blower assembly from the furnace by taking off the nuts or bolts that hold it in place. Loosen the screw that connects the wheel to the motor and remove the motor mounting bolts. Once the motor’s out, you should remove the mounting bracket. But before you do, draw a diagram showing the relative position of the motor in the bracket so you can reinstall it correctly later. If the mounting bracket is built into the motor, you will need an adapter kit if you can’t find an exact replacement motor.

Replacement

• Your old motor should have a number on it, which you can use to help you find an exact replacement. You may be able to use a universal replacement if the diameter of the motor, the voltage, horsepower, revolutions per minute, number of speeds, direction of rotation, mounting method and the size of the run capacitor are the same as your old motor.

Installation

• When installing your new motor, make sure the wheel is centered in the housing before you screw it back on. If there are unused motor leads, use wire nuts or electrical tape to isolate them. When you’re finished, let the furnace run through a complete cycle and ensure that everything is working properly.