How to Replace a Blower Motor

Replacing a blower motor takes about two hours.

The blower motor is one of the most important components in your air conditioning system. It is responsible for the circulation of air through your home and returning that same air to the air handler for conditioning. A malfunctioning blower motor causes your system efficiency to drop and can even cause a complete mechanical breakdown of other components, such as the compressor. You can keep your system operating efficiently and safely by maintaining this important component.

Things You'll Need

• Nut driver
• Adjustable wrench
• Factory replacement motor

Instructions

1. Switch the furnace circuit breaker to the "Off" position.

2. Remove the blower access panel from the furnace using a nut driver.

3. Disconnect the blower motor wiring harness and the two wires connected to the capacitor.

4. Remove the two screws attaching the blower assembly to the furnace housing and remove the assembly. The entire blower assembly, consisting of the squirrel cage housing, centrifugal fan blade, blower motor and capacitor, should easily slide out.

5. Loosen the shaft bolt connecting the motor shaft to the centrifugal fan blades and the three bolts connecting the motor mounting bracket to the squirrel cage housing.

6. Pull the motor out of the housing and remove the mounting bracket from the motor.

7. Mount the motor mounting bracket to the new motor and slide the new motor into the blower assembly the same way the old one was removed. Use a factory replacement part for best results.

8. Attach the motor mounting bracket to the squirrel cage and tighten the shaft bolt connecting the motor shaft to the centrifugal fan blades. Verify that the centrifugal blades spin freely and the shaft bolt is lined up with the flat section of the shaft before tightening completely.

9. Connect the capacitor wires from the new motor to the capacitor on the fan assembly. Identify the capacitor wires using the manufacturer's motor wiring diagram.

10. Slide the blower assembly into the furnace the same way it was removed. Connect the new motor wiring harness to the existing plug in the furnace. The harness will match up without any alterations if you're using a factory replacement part.

11. Replace the blower access panel and switch the furnace circuit breaker to the "On" position. Set your thermostat fan switch to the "On" position and test your new motor.

Tips & Warnings

• There is always a danger of electrical shock when working with electricity.

• Incorrectly repaired furnaces can malfunction and result in fire. Only qualified individuals should attempt this repair.

References

• "Refrigeration and Air Conditioning Technology"; Bill Whitman et al; 2008