How to Replace the Fan Motor on an AC Condenser
An air conditioner's condenser fan motor keeps the compressor from overheating and cools super-heated refrigerant as it flows through the condensing coil. When considering replacing a bad AC condenser fan motor, always keep in mind that the replacement motor must have identical speed and horsepower ratings. Universal replacement motors have multiple speed settings. Many technicians replace the fan's capacitor when changing a fan motor. Yearly fan maintenance, a drop of oil, can increase the life of an air conditioner's condenser fan motor considerably.
Disconnect the electricity to the condensing unit at either a disconnect box located near the condensing unit or in the circuit breaker box. Disconnect boxes mount on the house near the condensing unit and use either a removable bus-bar or a switch that looks like a circuit breaker. The label for the correct circuit breaker, in the circuit breaker box, should read either "air conditioner" or "heat pump."
Unscrew the control panel's access cover with the correct-size nut driver, usually 1/4- or 5/16-inch. Following the wire's conduit from the disconnect box, or where it exits the house, will lead to the control panel. Place the screws in a safe place.
Pull down on the access cover to release it from the top lip of the condensing unit's lid.
Place the leads from a voltmeter on the contactor's wire terminals. The thick high-voltage wires that enter the control panel connect to the contactor. The meter must read zero.
Unscrew the condensing unit's fan shroud with the proper-size nut driver, usually 1/4-, 5/16-, or 3/8-inch. Some models require removing the entire lid, while some only need the grille on top removed. Lift the lid to access the fan motor.
Cut the motor's wires inside the fan compartment with wire cutters.
Disconnect the fan motor from its mounting bracket. In most cases the motor screws directly to the mounting bracket, either through the top of the motor or through the side of the motor's case. Use a nut driver to remove these screws. Some models use a belly-band to hold the motor in place, which will require an adjustable wrench to loosen.
Loosen the fan blade mounting screw, located near the center of the blade, with an adjustable wrench. Pull the blade off the fan motor's shaft. A drop of oil placed on a rusty shaft will aid in removal.
Use the tag on the old motor to identify which color wires go to the capacitor, common and hot. Write this information with a pencil on a piece of paper. Do the same thing with the new motor. Universal replacement motors may have several different speed settings, using different colored wires. Compare the speed of the old motor with the tag on the new motor to find the correct color wire that corresponds with the correct speed.
Slide the fan blade onto the new motor's shaft. The blade's mounting screw must face away from the fan housing. Tighten the mounting screw with an adjustable wrench. Spin the blade to verify it does not touch any part of the motor.
Mount the new motor and blade to the condensing unit's fan mounting bracket. Use the new screws that come with the fan motor, if included, otherwise reuse the old mounting screws. If the unit uses a belly-band, slide the wires over the belly-band, push the fan into place and tighten the belly-band.
Pull the old wires into the control panel. Leave them connected for reference.
Push the new wires into the control panel.
Connect each new wire to its proper terminal, using the written information on the paper as a guide. Remove one old wire from its terminal at a time. Before moving to the next wire, connect the proper wire from the new motor to the terminal. One wire will go to each side of the contactor and, depending on the model, one or two wires will go to a capacitor. All extra fan-speed wires need wire nuts twisted on to protect them from shorting inside the control panel.
Screw the fan's shroud to the condensing unit and screw the access panel's cover into place.
Turn the power to the condensing unit on and test the fan.
Things You Will Need
- Nut driver set
- Wire cutters
- Adjustable wrench
- Wire nuts
- Recycle the old fan motor. Scrap yards will pay money for it.