How do I Fix Condenser Fan Trouble on a Central Air Conditioner?

Shut off the power at the unit's disconnect switch, then shut off the power to the unit at the main electrical service panel. Allow 10 minutes to let stored electricity dissipate before beginning repairs. Remember that these steps are essential to prevent electrocution and serious injury.

Remove the screws from the top access panel after all electricity to the unit has been shut off. Carefully lift off the panel. Unscrew the screws from the unit's side panel surrounding the condenser coils. The condenser coils are the small pipes that run through the sides of the unit and circulate refrigerant. Gently remove the side panel. Check for leaves, dirt and debris around the fan, condenser coils and motor. Remove that dirt and debris with a soft-bristled brush. Clean off any dust on the fins, the thin metal teeth that line the interior of your unit, and coils. Using a fin comb that matches the size of your fins, carefully straighten any bent fins.

Lubricate the fan motor. After straightening the fins and cleaning off all dirt and debris, replace the unit's side panel, ensuring that electricity is still shut off at the main electrical service panel. Inspect the top of the unit to locate the oil ports for the fan's motor. If the fan is attached to the top panel, the oil ports will be located above the fan blades. If not, wearing heavy gloves, loosen the set screw on the fan blade assembly. Remove the assembly and pry out the rubber oil plugs. Add three drops of all-purpose oil to each port. Replace the plugs and reattach the assembly so that it sits one inch above the motor.

Ensure fan blades spin freely and are not bent. With the power still shut off at the main service panel, spin the fan blades manually to confirm that they spin freely. Adjust the set screw until they rotate smoothly. If a fan blade is bent, the entire assembly needs to be replaced. To replace the fan blade assembly, remove the broken assembly, then line up the set screw of the new assembly with the flat side of the motor shaft. Gently slide the new assembly onto the motor shaft until it rests an inch from the motor. Tighten the set screw.

Replace the top panel and secure it with the top panel screws. Turn on the power at the unit and the main service panel. Set the indoor thermostat so that the unit turns on and examine the rotation of the fan. If the fan blades wobble or emit a strange noise, shut off the power at the unit and main service panel again and check the fan for interference, debris or a loose set screw.