How to Replace an AC Blower Motor 

Not having a working AC in the middle of a heat wave is the source of many distress calls. Although blower motors should last as long as the HVAC unit, a damaged or burnt-out motor is common repair when the unit has not been properly maintained. Add another skill to your HVAC tool bag and learn how to replace an AC blower motor.

How Do I Know If My AC Blower Motor Is Bad?

Blower motors are responsible for directing air through the vents in a home or building, so when they go out, they’re usually accompanied by some obvious signs:

• Little to no airflow – Blower motors push the air through the vents, so if you feel little to no breeze when you put your hand to them, this might be a sign the blower motor is not working at full capacity.

• Unusual noises – If you’re hearing rattling, screeching or banging coming from the indoor air handler unit, this could indicate a problem with the blower motor. Squealing or screeching noises likely point to an issue with the belt or bearing, while rattling noises may be associated with loose or disconnected components.

• AC starts then stops – A blower motor that’s on its last legs might be working harder than normal to maintain airflow, causing it to overheat. In this case, you may hear frequent cycling as the AC’s safety cutoffs are engaged.

These symptoms can masquerade as other problems like capacitor issues, thermostat malfunctions, clogged air filters and more, so it’s important to run a full diagnostic before replacing the air conditioner blower motor.

Where Is the AC Blower Motor Located?

The AC blower motor is typically located inside the air handler, which you’ll find hiding in the basement, attic or utility closets. For mini splits and window air conditioners, they’ll be located within the unit itself. You can open the unit through the access panel. If you’re unable to find the blower motor, refer to the manufacturer’s manual for more detailed instructions.

Is a Blower Motor Easy to Replace?

You should only replace an AC blower motor if you’ve been trained as a qualified service technician. Blower motor repairs, installation and replacements require technical and electrical knowledge that may be too advanced for the average homeowner or DIY enthusiast. 

Attempting a blower motor repair without proper training could result in damage to the HVAC unit, electrocution and even death. It’s best to leave these types of repairs up to the professionals. 

Supplies You’ll Need

• Real OEM replacement blower motor 
• Insulated Gloves 
• Goggles
• Adjustable wrench 
• Puller tool 
• Socket wrench or nut driver
• Screwdriver
• WD-40
• Sand cloth

How to Replace an AC Blower Motor 

Safety Precautions 

Before we teach you how to replace an AC blower motor, don’t forget to put on your electrical gloves and goggles and ensure all the power to the unit is off. When it comes to safety, don’t take any shortcuts. Always do it by the book so you don't get shocked when you start pulling wires.

• Step 1. Cut power to the unit – To ensure your safety, turn off the power at the breaker box and unplug the unit. 
• Step 2. Remove the service panels – Next, remove the service panel to access the capacitor, control board and blower motor. You might have to unfasten a couple of screws or bolts to get inside. 
• Step 3. Engage the safety switch – Some units will have a safety switch that allows you to cut power to the unit. Depending on the make and model, this switch might automatically engage when you pop off the access panel, while others require a manual switch.
• Step 4. Discharge the capacitor – We all know that capacitors can hold a charge even after the power to the unit has been turned off. Ensure you discharge the capacitor before you start touching the controls and wirings.

Removing the Old Blower Motor 

In this section, we’ll tell you how to replace an AC blower motor step by step. It’s important to keep in mind that not all AC unit’s internals are structured or organized in the same way, so you might have an extra step here or there while others may not:

• Step 5. Take a picture of the wiring – Before you start disconnecting the wiring, it’s a good idea to snap a few pictures just in case you forget how they fit back together later on.

• Step 6. Disconnect the wires – From there, detach the wires connecting the blower motor assembly to the control panel.  

• Step 7. Unbolt the control board – Depending on your unit, the control board might be mounted to the blower motor assembly. If this is the case, go ahead and unfasten the bolts securing it in place so you can remove it.

• Step 8. Unscrew the blower assembly from the air handler – Unscrew the mounting bolts that fasten the blower motor assembly to the air handler. Label and store them in a zip lock bag for later. Next, slide it out.

• Step 9. Remove the bracket mounting bolts – Most blower motors have a bracket that mounts the motor to the blower fan blades. Using a socket wrench or nut driver, go ahead and remove these now.

• Step 10. Unfasten the set screw – Flip the blower assembly over to access the set screw. You can use an adjustable wrench to loosen it. It’s not necessary to take it all the way off, but it’s a good idea to store it in a zip lock bag so you don’t lose it when you install the new motor.

• Step 11. Remove the fan blade from the shaft – As most already know, removing the fan blades from the motor is never as easy as it looks. Sometimes, you’ll have to sand down the shaft and spray it with WD-40 before using a fan blade or hub puller to yank it free.

• Step 12. Take off the motor mounting bracket – Loosen the bolts securing the mounting bracket to the old blower motor.

Installing the New Blower Motor

The hard part is over. Now it’s time to reverse the steps learn how to replace an AC blower motor with the new one:

• Step 13. Clean the blower fan blade – Before installing the new blower motor, use a brush, vacuum or cloth to clean the dirt, dust and debris from the fan blades.

• Step 14. Install the motor mounting bracket – When installing the mounting bracket onto the new motor, align it in the same position and, if possible, avoid covering the specs.

• Step 15. Install the new blower motor in the housing – Align the bracket with the three bolt holes on the motor blower housing to install. Double check the blower motor fan blades and electrical connections are pointed in the right direction.

• Step 16. Tighten the set screw – Ensure the blower motor fan blade is neither too far down nor up on the shaft. Give it a little spin to make sure none of the components rub together or make noise. Then, tighten the set screw. 

• Step 17. Connect the new wiring to the control board – Depending on how the internals are set up, you might need to reconnect the wiring to the control board before reinstalling the blower motor assembly into the air handler. Refer to the pictures you took, and don’t forget to ground the blower motor! 

• Step 18. Reinstall the blower motor – Slide the blower motor housing back onto the tracks and secure the bolts.

• Step 19. Reinstall the control board – With the blower motor housing back in its original position, reattach the control board if you need to. 

• Step 20. Replace the access panel – Fasten the access panel back onto the air handler unit with the screws from the bag you labeled early on. 

• Step 21. Restore power – Restore power by flipping any safety switches you may have engaged and turn the circuit breaker back on. That’s how to replace an AC blower motor!

What Is the Life Expectancy of an AC Blower Motor?

Most blower motors are designed to last about 10-20 years, or as long as the AC unit itself. However, there are a few factors that might reduce its life expectancy. For instance, a lack of preventative maintenance, like tune-ups, filter replacements and regular cleanings, can cause the motor to overwork and overheat. Have an authorized service technician perform seasonal maintenance at least twice a year to fix small problems before they become costly repairs.