Why a Condensing Fan Motor is Overheating

By | August 21, 2019

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A condensing fan motor should never be too hot to touch and be overheating on any unit whether it be a heat pump, air conditioner, or split system.

The easiest and most common way to check a unit is to quickly touch the top of it and while it should be warm it should not be very hot (too hot to touch) if so then there is likely a problem.

You can also measure the temperature with a thermometer, HVAC technicians often use infrared temperature guns that can read the temperature without ever touching the condensing fan motor, but a standard thermometer will also work.
 




 
Every condensing fan motor has a temperature it can safely operate at. This operating temperature is written on the side of the motor name tag which also has all the information about the motor.

Most motors run around 70 degrees Celsius or 150 degrees Fahrenheit.

Sometimes the name tag can be easily seen and sometimes it will have to be lifted out to see. Lifting out a motor is easy as they are usually mounted to a circular grate that has 6-10 screws holding it in place.

Be sure the unit is off when removing the screws, HVAC technicians pull the disconnect or turn off the breaker to the unit before doing any work. No one wants a unit to kick on spinning the blades while they are working on it.
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After checking the temperature it should be within the specified temperature range of the motor. If it is not then more than likely the motor is bad or something is causing it to over amp. Usual causes of a over amping condensing fan motor is when it has the wrong start run capacitor or wrong fan blade. If no work has been done to it lately then most likely the motor has gone bad.
 
Replacing a condensing fan motor is fairly simple and can save you a lot of money for the DIY (Do it yourself) type of person. A HVAC company will charge around 400 to 500 dollars maybe more to come out and fix it for you. While buying a new motor yourself runs 60 to 150 dollars. Of course care has to be taking, if a motor or start run capacitor is wired wrong then it can burn up a motor and cost more money. If you have wired up a wall socket, roof fan, or other electrical house hold items then more then likely it will not be a difficult job.
 
There are many YouTube videos and books that can show the necessary steps.
 
Replacing the start run capacitor should also be done at the same time. Using the old start run capacitor with a new motor can damage a new motor.
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The information needed for buying a new motor and capacitor are written on the side of each.

The problem for many DIYers is that places like Home Depot or any home supply store do not carry these parts. Finding a HVAC service company that will sell you the parts is an option but they usually mark up the prices when they sell to a home owner. The good news is that these parts can be easily ordered online at Amazon or eBay.
 
Example Condensing Fan Motor On Amazon.
Fasco D7909 5.6-Inch Condenser Fan Motor, 1/4 HP, 208-230 Volts, 1075 RPM, 1 Speed, 1.8 Amps, Totally Enclosed, Reversible Rotation, Ball Bearing

 
The same can be done with the start run capacitor by looking at the tag for the MFD and voltage.
 
Example Start Run Capacitor On Amazon.
GE Genteq Capacitor Dual Run Round 35/5 uf MFD 370 Volt VAC 97F9834 (replace old GE Z97F9834) 35 + 5 MFD at 370 volts

 
For all the home Do-it-yourself self people out there I’m sure replacing a condensing fan motor and start run capacitor will be a great way to save money.

Of course if in doubt be sure to call a professional.



 




 

15 thoughts on “Why a Condensing Fan Motor is Overheating

  1. Hunter

    Tried installing a new motor and capacitor, however still kicked off after 10-15 minutes. Pressure as well as amp readings were all within respected limits. Any ideas on what I might try or what the issue is?

    Reply
  2. Relay

    Hi, after a major storm my heat pump fan stopped starting (and there was even some smoke coming out of the fan as it was not starting and overheating). I have replaced the capacitor, switch, and antifreeze board. Everything seems to run OK now but when the AC goes off the top of the fan is getting hot and become hotter and hotter over time (the AC reaches the preset temp and the system turns itself off as it supposed to–no compressor buzzing and fan turns itself is off (?)–it does not spin but getting hotter). Any help how to solve this issue? Thanks!

    Reply
  3. KEITH WOODY

    I’m having the exact same issue old carrier unit I’ve changed fan motors capacitors everything I can think of and at 15 to 20 mins my amps jump from .8 to 19 and shuts it down my unit is a 460 3ph HELP

    Reply
    1. Flaki

      Did you ever find the solution, i have the same problem, changed the fan motor also the capacator hut still the fan stops working , i have to turn it off and on to get it move after

      Reply
  4. Diane Devers

    My fan stops After 5 mins and all you hear is a.c. humming .you turn it back on a 2 hours later it does samething. Is fan motor bad

    Reply
  5. Jim

    I have an old 1974 Luxaire AC unit. It runs ok then after running for about 20 min. the other day the fan motor froze up and buzzing noise coming from unit. Tried the fan spin—no go on that. A lot of high temp–heat coming from of the top housing above the fan. Let everything cool down for awhile and then the same thing happened again. I figure the fan motor is cooked. The problem I have is the unit is 42 years old—If I can find a motor and capacitor I believe it will generate new life into the unit. Are motors still available for that grandfather front slant unit ?

    Reply
    1. Aaron Benetti Post author

      I’m sure you can wire in a new motor even add a start/run capacitor if needed. If the tag can still be found on the motor than you should be able to replace it easily as you can quickly match up another motor with the same RPM, HP, voltage and amps. Let us know how it goes.

      Reply
  6. Bryan Nahaj

    I’m currently working on a window AC . The fan speed is very slow. It will change speeds but the high is similar to low and medium is even slower and low is very slow.
    I thought it may be the fan capacitor or the run capacitor. Everything else is working fine. My main goal is to get the speeds working normal to the proper settings.

    Reply
    1. Aaron Benetti Post author

      It sounds like the motor is going bad but would need some test to be sure. Do you have a HVAC Multi Meter that can test the capacitor that’s the quickest way to rule it out.

      Reply
  7. Michael schiano

    I replace the mother and capacitor its work fine for a while when run for awhile the motor does nor stare until it’s cool off also when it on there no air blowing up could the trouble

    Reply
  8. Jason

    I had the same problem, new motor new capacitor, overheats and shuts off… Found I had connected two wires incorrectly. C on capacitor is for common power(usually yellow) from the contractor block, HERM is for the compressor( usually a blue wire) and fan is for the fan. If the fan runs the wrong rotation switch the wires on C and fan…

    Reply
  9. Thomas Bryant

    I have the same problem. Replaced motor twice and overheats after about 15-20 minutes. It is 208/240 v on 240v ststem. I also installed new cap and still did the same thing on second motor.any ideas would be helpful.

    Reply
    1. Aaron Benetti Post author

      A bad capacitor is the most common cause but it can also be many other things. One thing overlooked often is make sure the fins of the unit are not clogged up making the fan work harder trying to pull air. A tech would check the Amps the motor is drawing and match it to the motor to see if it is Over-Amping and than go from there. Let us know how it goes.

      Reply
  10. Goabaone Meshack Ikatlholeng

    I got a situation whereby a outdoor fan motor of 12000btu LG is heating up and stop after running for about 20mins,i have replaced with a new one but still does the same.

    Reply

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