How to Replace a Central Air Conditioner Fan

What You'll Need
Crescent wrench
Penetrating oil
Wire Cutters
Replacement motor and capacitor
Hub and fan blade puller
Vise grip
Rubber mallet

You might need to know how to replace a central air conditioner fan if the motor fails. Even if the motor works, it is highly recommended that you remove the fan to clean it thoroughly on a regular basis. Deposits of dirt impede airflow and reduce the effectiveness of your ventilation system. If fan blades become contaminated with mold or bacteria they can threaten the health of the building’s occupants. Replacing air filters regularly will extend the life of the central fan.

Step 1 – Locate Air Handler

The air handler of your central heating and cooling system will resemble a large drum. In older construction it may in a mechanical room. In newer homes it is usually in the attic. The mechanical room or attic will contain a large metal box with ductwork connected to it; the air handler is usually inside this box and can be accessed through a kick panel. In apartments with small systems, the air handler may be in the ceiling directly above the main air intake.

Step 2 – Lock Out Power

Shut down the electrical circuit servicing the air conditioning system before removing the motor.

Step 3 – Remove Blower Motor Assembly

The air handler assembly is probably attached to the outer casing using a few bolts. If there are junction boxes or other obstacles between the motor assembly and the kick panel, these may also have to be removed. Finally, you may have to cut wires connected to the motor in order to free the assembly. If this is necessary, cut the wires as close to the motor as possible.

Step 4 – Remove Motor Casing from Air Handler

Before removing the motor, note the location of the mounting brackets which hold it in place. These brackets are generally not included with replacement motors.

Step 5 – Remove Squirrel Cages from Motor Axles and Clean Them

Depending on the specific model there may be one or two “squirrel cages” seated on the motor axle. The fans could be held on with a ¼-inch square bolt, metal collars, or nothing at all. Use the vise, rubber mallet, and penetrating oil to tap the cages off the axles. Do not bend the fan or flatten the tip of the axle. Once the cages are free, clean them thoroughly. A special tool called a hub and fan blade puller is available but it is expensive.

Step 6 – Service or Replace Motor

Disassemble the motor to examine brushes and bearings or replace the whole thing. Make sure the new motor is compatible with your equipment and install it according to the manufacturer’s wiring diagram.

Step 7 – Replace Run Capacitor

Blower motors have a capacitor to smooth out alternating current voltages. It is generally recommended to replace this capacitor anytime the motor is serviced.

Step 8 – Reassemble and Reinstall Equipment

Restore the equipment to its original configuration and test it out. If you are still having problems consider calling a licensed refrigeration technician.