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How to Replace an AC Fan Motor 

Condenser unit opened for service - How to replace an AC fan motor

If the AC fan motor goes out, you’ll be sure to get a call. To ensure your faithful customers stay that way, it’s important to diagnose the problem as efficiently and accurately as possible while making the repair in a timely manner. To do so, it can be helpful to have a reference point for common faulty fan motor symptoms with step-by-step instructions. So whether you’re a technician in training or just need a little refresher, we’ll walk you through how to replace an AC fan motor.

How Do You Know If Your AC Fan Motor Is Bad?

Identifying whether the air conditioner’s problem is due to a faulty fan motor or something else is crucial to ensuring happy, repeat customers. Listed below are a couple of common symptoms that suggest the AC fan motor has gone bad:

  • Fan doesn’t run – The fan motor should run nonstop during the cooling cycle. However, if the fan isn’t running, it may be because the motor failed or overheated. Be careful, though, as a non working fan motor may also be caused by a bad capacitor, tripped circuit breaker, faulty wiring or other electrical issues.
  • Fan starts then stops – Intermittent performance is another sign of a failing fan motor caused by overheating or loose wiring. 
  • Fan blades are slow to turn – If the fan blades turn like a carousel in an abandoned playground, it might be a sign that the motor is on its last legs.   
  • Warm air – If the fan motor in the condenser unit isn’t working, the absorbed heat won't dissipate as effectively, causing warm indoor air temperatures.
  • Unusual noises – You may hear a rattling noise, indicating a worn-out bearing or other components. 

Can I Replace My Own AC Motor?

Do not attempt an AC condenser fan motor replacement unless you're a trained professional. This repair requires in-depth technical and electrical knowledge that could result in damage to the unit, electrocution and even death if you do so without the proper training, equipment and safety precautions.

In addition, service technicians have the background knowledge and tools to diagnose the problem with your AC unit. Sometimes, the symptoms of a broken fan motor overlap with other issues, like faulty wiring, capacitor thermostat and other problems that a fan motor replacement won't resolve.

Supplies You’ll Need 

How to Replace an AC Fan Motor 

On average, this repair will take around 1-3 hours, depending on your experience level, the type of AC unit and how accessible it is. Regardless, give yourself plenty of time to make the repair without rushing. So, without further ado, we’ll take you step-by-step through how to replace an AC fan motor:

Safety Precautions 

  • Step 1. Cut power to the unit – First things first, don your PPE. Then, turn off the thermostat and cut power to the unit at the circuit breaker.
  • Step 2. Remove the access panel – With a screwdriver or electric drill, remove the screws securing the access panel to the condenser unit. 
  • Step 3. Verify with a multimeter – For safety, verify there’s no power coming to the unit by testing the contactor with a multimeter.
  • Step 4. Discharge the capacitor – Before you start tugging at the wires, discharge the capacitor to prevent any accidental shocks!
close up of the interior of an AC fan motor - How to replace an AC fan motor

Removing the AC Fan Motor 

  • Step 5. Take the top off the unit – In some cases, you’ll have to unscrew the top panel before you’ll be able to remove it. 
  • Step 6. Remove the faceplate fan grille – Next, unfasten the faceplate from the condenser unit and store and label them in a zip lock bag. You can go ahead and loosen the screws and any that may be securing the wire sleeve as well.
  • Step 7. Take a picture of the wiring – Before you start unplugging wires, it’s a good idea to snap a few pictures just in case.
  • Step 8. Loosen the set screw – Before you can remove the fan blade, you’ll need to loosen the set screw. It’s not necessary to take it off all the way, but if you’re worried about losing it in the grass when you remove the motor, you can store it in a secure place.
  • Step 9. Remove the fan blade – Now comes the hardest part of replacing an AC fan motor in an air conditioner. You can help loosen the blade by sanding down the shaft and spraying WD-40
  • Note: Never use a hammer or other tool to beat the fan blade off or use channel locks on the motor shaft, as this could damage the assembly and make it harder to repair later. 
  • Step 10. Remove the faceplate from the fan motor – Loosen and remove the nuts and screws holding the faceplate to the fan motor. Store them in a safe place so you can use them again later.

Installing the AC Fan Motor

  • Step 11. Thread the wires through the sleeve – Before you bolt down your new condenser fan motor, it’s a good time to thread the motor through the sleeve.   
  • Note: If your unit does not have a wire sleeve, you can zip-tie them to the faceplate to keep them out of the way of the fan blade.
  • Step 12. Mount the new motor to the faceplate – Next, fasten the motor to the faceplate using the nuts and screws you removed in step 10. Go ahead and fasten the screw to the wire sleeve as well.
  • Step 13. Reinstall the fan blade – Insert the fan blade onto the motor shaft. You can refer to the old fan motor to approximate its location on the shaft.
  • Step 14. Tighten the set screw – Use a wrench to tighten the set screw to the flat side of the shaft. Do not over-tighten it.
  • Step 15. Put the faceplate back on the condenser unit – With the AC fan motor now firmly attached, replace the faceplate on top of the condenser unit. Don’t forget to route the wires through the condenser unit housing so you can attach them in the next step.
  • Step 16. Rewire the AC condenser fan motor – Next, reconnect the wires, referencing the pictures you took earlier if you have to. Don’t forget the grounding wire.
  • Step 17. Replace the access panel – From there, reinstall the access panel with the screws you set aside in step 2.
  • Step 18. Restore power to the unit – Last but not least, restore power to the unit by flipping the circuit breaker and thermostat back on. That’s how you replace an AC fan motor on the condenser unit!