Replacing failed motors on HVAC/R systems is a major part of the service technician’s job. In fact, you will be replacing motors on weekly if not daily bass.

In order to ensure that the process runs smoothly, verify that the proper replacement blower motor is on hand and all mounting and wiring is correct. This step by step procedure teaches how to do it.

This article is for instructional purposes only. Please do not attempt this without proper training and/or supervision.

TOOLS YOU WILL NEED: Screwdrivers, nut drivers, Allen keys, blower wheel puller, adjustable wrench, penetrating oil, sand cloth, rags, and operating condensing unit, replacement blower motor, digital multimeter (DMM), clamp-on ammeter, and safety glasses.

SAFETY: Make certain that all power is disconnected to the unit and that all capacitors are safely discharged.  DO NOT attempt to stop a moving blower wheel in any way. 

REPLACING AN OEM BLOWER MOTOR STEP-BY-STEP

  1. Make certain that the power to the unit is off and the power is disconnected.
  2. Carefully remove the service panel(s) from the air handler that is(are) covering the condensing unit’s electrical components.
  3. Trace the condenser fan motor wiring back to the service panel. Sketch a wiring diagram or take a photo of the wiring configuration
  4. Before disconnecting wires, make certain that the capacitor is properly discharged.
  5. Carefully remove the motor wires from their connecting points in the condensing unit. At this point, the motor is electrically disconnected from the condensing unit.
  6. Remove the fan guard grille from the top of the condensing unit.
  7. Remove the four nuts that secure the blower motor to the fan guard grille and remove the motor and fan.
  8. Loosen the set screw that secures the fan blade to the condenser fan motor. 
  9. Mark the fan blade’s hub position on the motor shaft.
  10. At this point, the fan blade can be removed from the motor shaft. At times, you will use a hub puller to assist with the fan blade’s removal.
  11. If needed, use sand cloth to remove rust and spray penetrating oil on the shaft to help loosen the blower wheel from the shaft. Be sure to allow a few minutes for the penetrating oil to do its job. 
  12. Slide the new fan blade onto the new motor’s shaft, using the previously marked hub position as a reference.
  13. Using the set screw, tighten the fan blade onto the motor shaft. The motor is now be securely mounted.
  14. Reattach the motor and fan on the fan guard grille and tighten the four mounting screws.
  15. Carefully reinstall the fan blade, condenser motor, and fan guard grille back onto the condensing unit.
  16. Reroute the motor wires to their connection points, making certain that the wires are secured, are not pinched between panels, and cannot come in contact with the rotating fan blade.
  17. Route the motor wires to their connection points, making certain that the wires are secured, are not pinched between panels,  and cannot come in contact with the rotating fan blade
  18. Using the diagrams and sketches that were drawn (or pictures taken) in earlier steps, carefully make the appropriate motor wiring connections. Be sure to double check your work, as motor damage and/or personal injury can result if wiring connections are not correct.
  19. Attach the fan guard grille to the condensing unit.
  20. Using a long screwdriver, manually spin the condenser fan blades. Check to ensure that no contact or rubbing occurs between the fan blades and any wiring or piping inside the condensing unit.
  21. Energize the condensing and set the thermostat so the condensing unit operates.
  22. Ensure that the motor is operating and that there are no unusual noises or vibrations. Replace the service panels on the condensing unit.
  23. Using your clamp-on ammeter, measure and record the amperage draw of the motor.
  24. Replace and secure the service panels.

Make sure that the fan blades do not get bent or damaged in the process.

If you would like to learn HVAC Blower Motor our online HVAC Training can help you learn the fundamentals of HVAC so that you can apply for an HVAC position with confidence and basic HVAC training.


Ron Walker
Ron Walker

After retiring from the U.S. Marines and achieving his B.S. degree, Ron Walker entered the HVAC field. He has been an HVAC technician, service manager, and business owner. Working as a service manager, he spent many years training HVAC technicians to be more technically competent and really understand their trade. His passion for teaching and helping others resulted in the creation of HVAC Training Solutions, LLC.