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Problem: Why does my air conditioner fan motor keep burning up?

troubleshooting air conditioners and heat pumps

Question: In May I started to have some problems with my outside ac unit. My fan stopped running but I could get it back running by spinning the blade when it hmmmmmed. Blade was easy to spin Called an AC Company to see what was wrong They said the fan motor was bad and put in a new fan motor and oval capacitor.
But didn’t replace the dual capacitor said it didn’t need to be replace it was good. Ran good and cooled down the house good for about a mouth or so but started having the same problems. My fan stop running I could get it back running by spinning the blade when it hmmmmmed. Blade was easy to spin, but motor was hot to the touch
Ac company came out again said it was a bad new motor. Company put in a new fan motor and oval capacitor but didn’t replace the dual capacitor said it didn’t need to be replaced that the capacitor was good. Ran good and cooled down the house good for about a mouth or so but started having the same problems. My fan stopped running but it’s hard to spin now and takes a couple of tries to spin when it hmmmmms. The motor was hot to the touch. Now the fan motor won’t start to spin by me spinning it at all. It is too hard to spin. Note: The motor is still hot to the touch. What could be possible wrong with my unit? Why does my fan motor keep burning up?

Answer: Hi! I am so sorry to hear that you are having all these problems with your fan motor. There are several things that can cause a fan motor to go out prematurely. I will list some of them below then you can assess whether any of these might be causing your fan motor to go out so often.
1. Installing a universal fan motor that is not matched correctly with the right RPM or horsepower to power the fan blade. Motor not matched to the diameter and pitch of the fan blade. Motors should be matched (RPM, Horsepower, Amps) with the fan blades or it will over-load the motor and the motor will fail soon.
2. Having a fan blade that is off-balance and causes vibration to the motor and unit. A new balanced blade would be best.
3. Installing a fan motor and capacitor where the capacitor does not match the specs on the label of the fan motor. The fan motor capacitor should match the specifications on the motor label.
4. Installing a fan motor where lots of moisture is present like from a leaking gutter or down spout. Water pours on to fan motor when it rains or when snow melts.
5. Not having the rain shield installed (when required) or leaving drain plugs open where water and moisture can get into the motor. Some motors have rain shields to prevent water from getting into the motor. Many universal motors do not have rain shields, but have drain plugs that can be opened or closed depending on how the motor is installed, horizontal, vertical, shaft up or shaft down.
6. Improper wiring. Where the motor is not wired according to the label on the motor.
7. Improper rotation of the fan blade. With the fan blade spinning in the wrong direction the motor will not load and it will burn up over time.
7. Grass, weeds, plants or children that stick into the fan blade path and stop or impede the fan motor when it is running.
More than likely the HVAC company you had installed a universal fan motor. Many of these motors use an individual capacitor and this is why they did not hook into your existing dual capacitor. They probably are using the dual capacitor for the compressor only and the fan motor they installed has a separate single capacitor. I am just guessing. I am thinking that probably number 1 is probably the problem. That is why we mostly sell OEM fan motors so they will be matched with the fan blade and the customer has an easy time with the installation. If you would send your unit’s model number I will try to find out which OEM motor fits your unit. Our support email address is: support@arnoldservice.com. We will be glad to try and help you out!  Steve Arnold

Please comment below if you would like to add to this post or email us at: support@arnoldservice.com

14 thoughts on “Problem: Why does my air conditioner fan motor keep burning up?

  1. The inside part of my A/C and Heat is an American Standard and all electric. The fan motor went out on the inside unit…it was a slow process and I smelled something like my Ozone air purifier puts off, absolutely no burnt smell. After 5 days of that it stopped working. I called a repairman and they took out the housing and the fan motor and came back with a new motor in the old housing. Immediately when they installed it, it smelled like my house was on fire and smoke began coming out of the vents and began to fill the house with smoke. They told me that was normal and it would stop in a minute…well it did when the new fan motor burned itself out, about 45 seconds. Why did the new motor burn out? They blamed it on my A/C unit and said I need an entire new unit now, that something is making it burn up fan motors and they are not going to take the chance and put another new motor in to burn up, and followed up with “lady, its over 100 degrees out, you don’t have a choice.” I reminded them they had not ever told me how much the fan replacement was going to cost and what if it was more than I could afford….and they replied “Does it matter? You have to fix it anyway, you can’t live in this heat.” So now I don’t trust them. Can you tell me why the new fan motor burned up and could it have damaged anything else on my unit?

    1. Hi Robin! So sorry to hear that this motor burn out happened to you! When the motor started smelling hot they should have know the motor was not right! It sounds like that they installed either a bad motor or the wrong size motor for your system. Motors are sized based on the blower wheel size and if they installed a motor that did not match the blower wheel then it would burn up. For a motor to burn out that soon the motor must have been bad or they wired it wrong. They should either install a new motor or give you your money back if they do not want to install a new motor. Just because a motor burns up is not a reason to get a whole new air conditioning system! I would not trust these guys and would recommend that you search the BBB, Better Business Bureau, Angie’s List or Home Advisor for a contractor that has excellent reviews. Some of the contractors here in Louisville, KY will bring in portable AC units until they can fix the problem and get the AC back on. I hope you can find a contractor like that! So sorry to hear this happened to you in this heat! God bless you! I hope and pray you can find a great HVAC contractor to get your air back on. Steve

  2. Hi! The how to videos make it look cut and dry but … Surprisingly our unit fan stopped working after 10 yrs…started w terrible humming noise. So changed out capacitor made sure all the values matched. Nope fan still hummed. We bought a Wagner motor WG840465 universal horsepower choices, ours was 1/5 1075RPMS 208/230v..this is where it got “exciting ” none of the wires match! Old motor Black, Brown, ORange, W motor Black, Red, White, Brown -white, directions not clear w motor. First hook up of wires after ten You Tube how to’s ..did Brown, White (for old orange) and Black , secured and taped Red and BW not used, epic fail fan flew off even though secured tightly and everything got super hot in seconds,when pulled all back out W motor had sticker on side that you had to match RED or BLk to your needed horsepower . We re -did it again this time using RED where BLK was. Everything back together safely secured, grounded, double checked all ..Turned on breakers ..fan turning right direction but terrible noise, like its unbalanced. Pulled fan blade , there is wiggle at hub where it secures to motor post, seems like fan blade hub/ bearingsis bad and no one has exact fan blade online (Sat night repair ) . How can you double check correct wire colors and are fan blades universal if you can match up correct diameter. Original fan blade Weatherking (Rheem) 70-21858-10 . After 3 hours work and still no functioning AC.

    1. Hi! So very sorry to hear that you had all these problems installing a universal fan motor. This is why we do not sell too many universal motors because they are hard for our customers to wire up and make run right. The new universal motor has to match the old motor you are replacing with the RPM’s, horsepower, rotation, and amp rating. The new motor label should tell you how to wire the motor to get the 1/5 horsepower. Yes, the blade shoud match the motor RPM in the diameter and pitch. Below I copied from our Rheem Ruud parts program the new fan blade part number and specs which is part number 70-102033-05. Yes, if the fan blade flew off the motor and got out of balance then you will need a new fan blade. We do not sell or stock fan blades. If you want to send me a picture of the motor label with any questions you have please send it to our email: arnoldservice@gmail.com. Hope you get your AC fixed soon! Steve
      70-21858-10
      Description: Fan Blade
      Status: This part has been replaced by 70-102033-05
      Parts Information
      Technical Data
      Where Used
      Replacement History
      Database Information
      Shipping Information
      Technical Data »

      No. of Blades: 3
      Overall Diameter (in.): 18
      Rotation (Facing Air Discharge Side): CCW
      Pitch (Degrees): 30
      Bore Diameter (in.): 1/2
      Hub Location: Inlet Side

  3. Ok I bought a new ac the wires are all good but when we turn the air on the mitet burns why

    1. Hi Lovida!
      So very sorry to hear that you are having this problem with the motor burning up. It sounds like the HVAC company that you hired does not know what they are doing. I would like to suggest that you call a company who is a dealer for the brand name equipment that you have. For example, if you have a Carrier unit then call a Carrier dealer to service and fix the problem. Some companies do not know how to work on brands that they are not familiar with. I am sorry, that I can not be of more help, but it would be almost impossible to tell what the problem is without seeing pictures or being there to troubleshoot. I hope you can get the problem resolved soon!

  4. changed the motor it worked for a few hours then stopped, compresssor stayed on though

    1. Hi Kevin! I do not know what could be your problem if it is not covered in the post I wrote on “Why does my air conditioner fan motor keep burning up”. Most of the time when a motor stops after 2 hours the cause is because the motor does not match the fan blade and the motor is running too many amps over the FLA rating on the motor. The motor over-heats goes off on thermal overload and then the motor stops until it cools down. I would make sure that the replacement motor that you installed is equal in horsepower, RPMs and amp rating as the old motor your replaced. You might have an incompatible motor or a new motor with a dragging bearing that is causing the motor to run high amps. I hope you can find a solution soon! I know it is pretty hot in most places across the U.S. God bless you and your family. Steve

  5. I have a American Standard 13 seer.Ive had this unit about 7 years. After the 1st year the compressor went out. The warranty covered thr compressor. The a c guy charged as red me $1000.00 for the freon that he said it could not be reinstalled as it was contaminated…….any way today my fan motor hums and blades do not turn very easy. They are sluggish. So I think that the fan motor and the fan capacitor need replaced.capacitor just to replace with new.Is TV hi as the correct diagnosis…I’m an electrician by trade.but experience leads me to TV his.I’m not an a/c guy by no means.Thank you got you knowledge.

    1. Hi Eric! Sorry to hear that you are having trouble with your 7 year old American Standard AC unit. Since you are an electrician it should be easy for you to test the fan motor to see if you need a new motor. I would suggest that you test the two wires that go into the fan motor with the unit running. If you are getting 220 to 245 volts AC to the fan motor and it is not running then you either have a bad fan motor or a weak capacitor. You said that the motor blades do not turn easy so more than likely you need a fan motor because this sounds like the motor bearings are shot. If you would like to send me your unit’s model number I will be glad to look it up and find out which fan motor American Standard, Trane recommends. Please send your model number to our email address: arnoldservice@gmail.com. Thanks! I hope you have a great day and weekend! Steve

  6. I have the same issue before, the AC guy didn’t explain much about it. Thanks for sharing.

    1. Thanks! I hope this page helped you find out what might be wrong that is causing your fan motor to burn up. Hope you have a blessed Memorial Day weekend! Steve

  7. Is it dangerous when pilot gos out but still can fell heat.wat drawing heat no pilot lit?

    1. Hi Ms. Perez! If your pilot goes out during a heating cycle you will feel some heat come out of the furnace until the furnace heat exchanger cools down. This is not dangerous because most pilots that I have seen have a safety device called a thermocouple that will not allow the main gas valve to open if the thermocouple does not sense the heat of the flame of the pilot. So if the pilot flame is out the thermocouple will not allow the main gas valve to open until the pilot is lit again and has a flame. I hope that I have answered your question. I hope you have a great day! Steve

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