How to Replace a Blower Motor on a Home AC

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An air conditioner's blower motor that has worn out or has an electrical short can cause the inside coil to freeze up. When this happens, replacing the home's AC blower motor will solve the problem. Without adequate air flow, condensation gathers on the evaporator coil, and the subfreezing temperature of boiling refrigerant causes this condensate to turn to ice. During a service call, a technician will verify that the blower motor and its capacitor operates before checking refrigerant levels.

Things You'll Need

  • Nut driver set
  • Wire cutters
  • Adjustable wrench
  • Oil
  • Turn the electricity to the air conditioning unit off at the service disconnect box. Follow the wires from the AC unit to the disconnect box, usually located next to the unit. Open the disconnect box and, depending on the type, either pull the buss-bar or flip the disconnect switch.

  • Open the air handler's access panels with the correct size of nut driver, usually 5/16- or 1/4-inch. Save the screws.

  • Remove the control panel's cover, if equipped, with a nut driver. Some models have a flat metal cover over the electronic controls, and some control panels butt up to the unit's access cover. Save the screws and access cover.

  • Follow the wires from the blower motor. Two wires will go to a capacitor located on the blower's housing. The rest of the wires will go to the control panel.

  • Cut the wires leading into the control panel with wire cutters. Leave the cut wires connected inside of the control panel.

  • Remove the retaining bolts with either a nut driver, usually 3/8-inch, or an adjustable wrench. The retaining bolts, found on the mounting brackets that the blower's housing slides on, keep the blower's housing locked into position. Save the bolts.

  • Slide the blower motor's housing out of the AC unit. The housing will slide straight out along the mounting brackets.

  • Disconnect the two wires going to the capacitor. They will pull straight off the capacitor's terminals.

  • Unscrew the squirrel cage's locking-screw with an adjustable wrench. The squirrel cage, the bladed wheel, connects to the blower motor's shaft inside of the housing. The locking screw holds the squirrel cage to the shaft.

  • Unscrew the blower motor's mounting screws with either a nut driver, usually 3/8-inch, or an adjustable wrench. These screws hold the motor to the housing and are found on the opposite side of the squirrel cage, the same side that the wires leave the motor.

  • Pull the motor from the housing. A drop of oil on the shaft will aid in removal. If the squirrel cage sticks to the shaft, then hold the shaft still with an adjustable wrench while spinning the squirrel cage on the shaft.

  • Slide the new blower motor into the housing. The blower motor's shaft will slide into the squirrel cage's hole.

  • Tighten the blower motor's mounting screws.

  • Spin the blower motor's shaft until the flat part of the shaft lines up with the squirrel cage's locking screw. Move the squirrel cage in or out until it does not touch the housing or the blower motor. Tighten the locking screw.

  • Connect the blower motor's capacitor wires, usually brown or brown with white stripes, to the capacitor. Direct replacement motors use the same color-coded wires as the original.

  • Slide the blower motor's housing into the AC unit along the mounting brackets. Install the mounting bracket's retaining bolts.

  • Connect the new blower motor's wires in the control panel one at a time. Disconnect one old wire in the control panel. Determine its color and connect the new wire, of the same color, to its place. Do this for all wires.

  • Replace the control panel's cover, if equipped, and the unit's access cover. Turn on the power to the unit at the disconnect box and test the blower motor.

Tips & Warnings

  • Always use direct replacement motors. These motors use the same color-coded wires and have the correct horsepower and speed ratings for the system.

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References

  • Photo Credit Pompe à chaleur image by mattmatt73 from Fotolia.com
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