How to Replace a Furnace Circulation Blower Fan Motor

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Are you ready to learn more about your furnace circulation blower fan motor and how to replace it? Our blog post will tell you everything you need to know and talk you through the process of replacement.

What is the Furnace Circulation Blower Fan Motor?

As part of the heating or cooling system, the furnace’s circulation blower fan motor draws air through the return vent, blows it past the heat exchanger, and forces it through the homes venting. The room air is then drawn back through the return and the air flow cycle continues. The blower fan motor can run at multiple speeds to improve efficiency. Lower speeds are used when the furnace is heating, and high speeds are used for air conditioning.

A malfunctioning blower fan motor will be unable to provide heated or cooled air throughout the home. If the blower fan motor is noisy during use, the set screw on the blower wheel may have loosened, causing the wheel to wobble on the motor shaft. You can fix this problem by tightening or replacing the screw, or replacing the blower wheel all together.

If the motor itself is noisy, the bearings in the motor may have worn out. While some older furnace motors can be lubricated to reduce the noise, most current motors do not allow this and the motor will need to be replaced.

If the blower motor does not run at all, you should first confirm that the motor is receiving power. If it is, then it’s likely the motor has burned out.

Circulation blower fan motors are usually unique to each furnace model. You should enter the full model number of your furnace in our website search bar to find the specific fan motor you need.

How to Replace Your Furnace Circulation Blower Fan Motor

Before you replace the fan motor, first turn off the power to the furnace.

The blower fan motor is normally supported on rails near the bottom of the furnace. Since the motor power wires are connected to a control board that is often located in an upper compartment, two access panels may need to be removed. If applicable, you should ensure the motors run capacitor is discharged by placing a screwdriver with an insulated handle across the terminals. Avoid touching the screwdriver blade. Disconnect the wires from the capacitor terminals, if required. Depending on the furnace model, you may have to uninstall a drain trap assembly, and the attached hoses to access the fan motor. If necessary, you may need to disconnect the thermostat wires from the control board to move them out of the way. Note the orientation of the blower motor power wires, then disconnect them from the control board. Cut any zip ties if required. Move any additional obstructions out of the way. If necessary, note where the blower assembly mounting rails are positioned. Now unthread the screws securing the rails. Carefully slide out the blower assembly. Use an adjustable wrench to loosen the set screw to release the blower wheel from the motor shaft. If required detach the grounding wire. Cut any zip ties securing the motor wires. Now unthread the bolts or screws securing the blower motor. Note the orientation of the old motor, then lift it off of the blower housing.

When installing a new blower motor, you should confirm that the motors capacitor rating matches the existing run capacitor. If not, you will need to replace the capacitor with the required one. Insert the fan motor shaft into the blower wheel, as you properly align the motor on the housing. Thread and tighten the bolts or screws to secure the motor. Use zip ties to secure the wires and reattach the grounding wire if required. With the flat side of the motor shaft facing the set screw, center the blower wheel in the housing and tighten the set screw. Realign the blower assembly mounting rails with the slots on the support, and slide the assembly into position. Replace the screws to secure the rails. Reinstall any components you removed earlier. Attach the blower motor power wires to the appropriate terminals on the control board. Connect the capacitor wires, as required. If applicable, reconnect the thermostat wires as well. Use zip ties to remove any slack from the wiring.

With the new blower motor installed, replace the access panel or panels. Turn the power supply back on, and your furnace should be ready for use.

Watch our video on replacing your furnace circulation blower fan motor for a visual guide, or visit Repair Clinic for furnace parts supply and more furnace repair tips.

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