Diagnosing a Bad Blower Motor (8 Easy Things To Check)

Hey HVAC techs! I’m Greg Fox and today we’re going to talk about Diagnosing a Bad Blower Motor. I wanted to expand on our recent gas furnace troubleshooting series by going into each part of the sequence of operation of a furnace. This week, it’s the blower motor.
I'm going to give you 8 Easy Things to Check if you think you might have a bad blower motor. To diagnose a furnace can be intimidating. But if you follow these simple troubleshooting tips, you'll be on your way to repairing it.
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00:00 Intro
1:07 Sequence of Operation
2:24 8 things to check to see if you have a bad blower motor
6:00 Outro

[@foxfamilyheatingandaircond4696]

One more video in our series on Troubleshooting Gas Furnaces. Let me know your thoughts and experiences troubleshooting a blower motor!

[@lawrencebruce6492]

Excellent tutorial, Bro. You have great talent for explanation of theory without making it incomprehensive. Thank You

[@actechchris]

As always, great advice Greg! Especially the last tip.

[@foxairandheatinc8345]

Love the energy and knowledge. NOTE - At approximately 5:30 the statement was made that a dirty blower wheel weighs more and thus uses less energy, and the cleaner wheel weighs less thus using more energy and thus can cause a motor to burn up after cleaning it. While this may happen, the actual cause is for a different reason. A dirty blower wheel will pull LESS amps due to the restricted airflow (possibly MORE on the initial startup due to the increased weight). Once it's cleaned, the airflow will often increase considerably and will cause the motor to draw MORE amps. Combine this with already worn/loose bearings and the motor often times will exceed its maximum rated amps, will overheat and eventually burn up. Hope this helps.

[@sagemaster3408]

He said it weighs down the blower wheel and creates a strain on the motor . He never said a dirty blower wheel weighs more and uses less energy . ? I’m confused. Can you explain a bit more please ?

[@foxairandheatinc8345]

@@sagemaster3408 his statement is incorrect. See my comment above. A dirty blower wheel will pull LESS amps due to the restricted airflow (possibly MORE on the initial startup due to the increased weight). Once it's cleaned, the airflow will often increase considerably and will cause the motor to draw MORE amps. Combine this with already worn/loose bearings and the motor often times will exceed its maximum rated amps, will overheat and eventually burn up. So it's the increased airflow that draws the high amps, not necessarily a heavier or lighter wheel. The heavier wheel may pull more amps on startup but once it's up to speed that's minimal. So cleaning the blower will increase the airflow and cause the amps to go up and maybe cause the motor to fail after the cleaning because it is old and worn. Just something to watch out for.

[@sagemaster3408]

@@foxairandheatinc8345 I understand all that. I was just confused because you said that he said “it uses less energy”. He never said that. That’s what I’m confused about . Thanks for the info also

[@sagemaster3408]

@@foxairandheatinc8345 I understand that , we all understand that. He was wrong in his statement. We all know this. Thanks for commenting. But. You I guess u don’t understand what I’m asking. It’s ok. Have a good day.

[@foxairandheatinc8345]

@@sagemaster3408 wasn't trying to be critical just trying to clarify WHY the blower might fail after you clean it all up. Not the techs problem but it might come back and bite you. Maybe I'm not understanding your question, maybe it can be rephrased

[@tylertorres918]

You are a good teacher man. Thanks

[@jfoley1968jf]

Great info thanks Greg!

[@denizinan979]

Your presentation about blower fan diagnosing was one of the best I've seen on KZbin, thank you.

[@foxfamilyheatingandaircond4696]

Thanks so much.

[@izzymoney85]

Thanks Greg for another great! video keep up the good work 👍

[@mrgreen9086]

Great video liked the tip on putting 120 to the blower

[@AladinThSv]

Great explanation thanks

[@Honestandtruth]

This is Great Video of info👍👍

[@d.c2123]

Thank you so much!

[@marcosylvia5704]

Excellent video. Didn’t know you could jump out the fan motor to make sure it’s just the motor not working. Very cool.

[@foxfamilyheatingandaircond4696]

Thanks hope you can use that!

[@shane3000]

You can also do that on a heatpump outdoor fan , take off at DEfrost board relay and put to bottom of CONTACTOR , if it comes on you have bad board

[@mgpvii]

How about testing the blower motor by trying to turn it on without having it initiated by heating/cooling mode, ie, not in auto mode, fan on. Then you know it is not being stopped by the steps the control board goes through in the heating or cooling mode. I thought my fan was not turning on because of the flame sensor but tried turning it on through fan only mode and it didn’t turn in then either.

[@watermanone7567]

Another great video. Thanks

[@foxfamilyheatingandaircond4696]

Thx for watching!

[@eatshitanddie107]

thank you sooo much. my blower motor keeps surging turning on and off for a split second like it’s fighting to stay on. i think it might be a bad transformer , will see tomorrow

[@corniss]

My furnace would go off and few seconds later come back in and off and on. The motor got hot and smelled like burning. Is there a safety feature you can get that woukd just keep the furnace off completely. If I wasnt hime when this happened my home woukd have burned down.

[@thompson4620]

Thanks for the tips! Definately helpful! After cleaning out the wheel, 3 weeks later there was a rattling when the fan comes on. When to check and the wheel is tight on the shaft, yet the shaft is moving in and out about 1/4" which doesn't seem great. It's a stand GE/Carrier type (like shown in this video) is there a way to replace whatever the problem is? It seems like the shaft is part of the internals of the motor. Thanks!

[@mrcleanofhvac]

Amazing

[@EsaNalgona727]

My outside ac unit fan is fine...my ac in the basement is blowing but when it tries to kick in it goes to start up but then turns off...any advice?

[@alchemy1]

You said what about checking the resistance of the motor winding for short?

[@nadirk]

thanks for your videos, fixed my york diamond 80 in roseville myself due to your videos and some others.

[@foxfamilyheatingandaircond4696]

Fantastic to hear man! Thanks. Those things are solid.

[@AppreciatingLife]

@@foxfamilyheatingandaircond4696 I have one of these old york diamond 80. has not been tuned up in 20 years. Recently, it wont spin the wheel unless I manually spin it then, it starts right up... should I replace the bearing inside? or just go with a new motor?

[@dk_719]

What setting do I use on a multimeter. My blower just stopped working and we have a heat warning all next week and I can't get anyone right now

[@kastenusa]

My Climatemaster ECM blower motor makes knocking noise on start up. Does it need replacement in the near future? Or it can be repaired? Thank you!

[@MervsServiceSecrets]

Excellent and very professional video. I recently had an HVAC house call because the 115v wires in my air handler's juction box had fried out. The technician reconnected the wires and the air handler fan worked again! Yay! I figured I must have had an energy surge from a lightning strike in the area, but when he tested the AMP draw from the motor he quickly shut off the unit and said "WHOA! That's drawing nearly 7 AMPS! You need a new blower motor! This is unsafe!" Later, I noticed the sticker on the motor says *9.35 AMP!* !! Plus, the fan spins smoothly and freely. Is he just trying to sell me a new blower motor? Or is that truly an alarming AMP draw?

[@mrpriceisright]

7 amps is not high. a hair dryer or microwave would be much higher. As you noted it says 9 amp on the motor label. if it was high it would likely trip the breaker (presumably 20 amp circuit). In the video, he mentions 4-12 amps is typical (shows 8 amps on the one tested).

[@elkess1]

he just rip you off installing new fan motor.

[@tmitmi765]

All I have to do is spin the fan blade by finger and the motor is spinning again. Done this for many years . Where do I search for lubes or cleaners etc. I think maintenance will be a little bit hesitant to replace the whole thing as seen in the video if it is still functioning.

[@Jram1292]

What if it hums . Get hot n smoke starts coming out from it?

[@GiantSlayer-rr1vu]

I have a Reem Ac unit and the AC Unit runs for a minute and then it stops. The furnace was just replaced 2 years. Is the blower motor bad.? THe condensation around the copper pipe is freezing. Then i reset the furnace at it goes away for 10-15 minutes. Intermittent run.

[@squirrelmaster5485]

When my central heat turns on the blower fan turns on slow for a few seconds then turns off. Any ideas?

[@mattdrellishak9074]

you check amps with door off?

[@KeepPrayingCA]

I have no idea how to do any of this but quick question if a motor was bad would it just stop or would it show signs like slow down but still have some movement before it completely died? My parents heater stopped working and my Boyfriend went over to try to figure it out. He said it’s the motor that went out and plans on taking it to Grainger on the morning to try to find a replacement. Said it’s FORTY years old! REEM isn’t that crazy!? Wish they made them like that nowadays. And said they don’t even have the number online to Replace it with. I wish I was there to video tape him to see exactly what was going on so I could try to diagnose it myself. I shared your videos with him but not sure he watched cause ya know he knows everything 🙄

[@sagemaster3408]

Ty

[@foxfamilyheatingandaircond4696]

welcome!

[@macknumber9]

My blower is slow and can't feel any air out of the vents. If I turn off the system and wait and then turn it back on it will go nice and fast and blow air good and then slow down after 10 min or so. Also I hear some noises from the blower like it is trying to go faster but just cant...is there any test I can do to confirm it is bad before spending $500 on a new one?

[@JoelHernandez-vf5hp]

What if is pulling 5amps out of 9.5amps???

[@oliviacanales9376]

The heater seems to work well but lately I smell a plastic type burn smell. I'm afraid it may be a burnt wire. The smell us present in a/ mode as well as heat.

[@disnalee]

Mind did this. Heat keep coming on and off but no heat blowing to the room. Any help?

[@JamesWarford-ts9mn]

I got a third horse blower motor with three wires coming out of it Buster Brown capacitor wires can I change that with a half horse same wiring or will it be too much draw on it. And it's cold out can anybody give me a tip on that

[@SirLife-jf8rq]

I have a ge motor with a black and yellow wire and ground with a b c port what's hot

[@southfloridalegaldocprepse5648]

I had someone come out and checked out my a/c unit as it was not working at all. I heard a popping sound and smelled something burning. When the a/c guy got here he said I needed an indoor motor and capacitor replaced and a new contactor. He charged me $848. Does that sound reasonable? After he left I noticed the heat was not working at all but the a/c was blowing cold. However, the problem also is besides no heat working, the fan is running constantly even when turned to auto. The only way to get the fan to stop running is to turn it off at the breakers. Any suggestions? The a/c guy is saying this is a new problem to come back out; however, is this not something he should have checked when he was here? Possibly the fact that something burned could also mean it blew some fuses? I don't know but really wondering if this should not have been checked at the time he was here before he left and also seemed a bit high priced. Please let me know your thoughts.

[@pspmaster510]

Residential blower motors (indoor motors) are generally $150 to $300. While capacitors are less $20.

[@JamesWarford-ts9mn]

By the way is a York single wide furnace

[@xMarkuzx]

I installed a new Thermostat and my heat works perfectly but the AC and the Fan ON mode does not work!

[@metou3072]

Didn't hook up the wires properly

[@johnlira3316]

Can a failing blower motor cause freezing on the unit,,

[@foxfamilyheatingandaircond4696]

Absolutely

[@johnlira3316]

I have a split unit tech threw out the old freon and added 5 pounds for a mobile home and unit cools cold and turns on and off but when it gets hotter outside unit stays on and doesnt cool as much and freezes tech checked the coil and blower said it was clean what could it be

[@morgancael5500]

Awesome 😍💋 💝💖♥️❤️

[@chadwolfeschledgelsteinhau9697]

My blower seems like its slow so slow it overheats and shuts off

[@leetaalexander]

bet you can't figure this out: my blower fan runs great, ran all winter with NO noise. Now that it's summer, when the outside compressor unit kicks on - there is a 'bang' on my inside blower!!! it's SO LOUD it scares my animals and me, it wakes us up at night! :( the idiots that installed the brand new outside compressor unit are like beavis and butthead. duhh idk beavis what do you think... i am so mad at these pple, i know it can be fixed, there is no reason for an outside unit to make the inside blower fan BANG and 'sometimes' it's a bit slow to come on. Here's the kicker. you can turn the blower fan only, ON, all day and it never never EVER happens. EVER. But when that dang compressor unit kicks on - BANG! and idk wth these nuts are thinking. I mean, the dang unit was put in new 10 months ago, - still doing it. they did not run new lines for the gas or new wires, they just installed it w/the old copper lines from the inside unit to the outside unit. I AM SO MAD idk what to do, they need to fix it but claim they don't know nuthin'. :( can you PLEASE help? i have googled the entire internet and cannot find anything at all about this. :( thank you!

[@michaelkrailo5725]

When you said that a motor will burn itself out due to having less of a load on it after having cleaned the squirrel cage, that's when you lost me. That just doesn't make any sense whatsoever as less of a load means less current draw, not more. That's true for any electric motor.

[@Rut1971]

Trying to figure mine out now! Kicks on, lights up, blows (although weakly) than kicks back off. Flame sensor and pressure switch check out ok. End up with a 4 blink code on my Ducane furnace/ac unit.

[@cordellkrish4276]

I'm Alone 😍😥

[@julianjacob5443]

Hi Guys 😍💋 💝💖