AC BLOWER MOTOR KEEPS BURNING UP! What should I do!?

Safeefee

Hello! Please help! I payed out a big amount (probably foolishly) last year in April in order to have my AC Blower motor replaced. The unit continued to work fine but now the blower motor continues to burn up. Twice already. What could be the cause? Repairman seems unsure of the cause & says I just have a bad unit. The part is under warranty but he refuses to replace a third time. Please help! Thank you for taking time and reading. Any help would be appreciated.

ratio

How new is the ​unit itself? A few pics might lead to something, but not all causes a visible from the outside.

I hate to say it, but maybe it's time​ to find someone a little more competent. Click the "Find a Contractor" link in the blue bar at the top of the page & see if anyone is near you.

Ironman

Find a competent tech.

Try the "Find a Contractor" tab at the top of this page.

Jean-David Beyer

I am not a professional, but I was responsible for two forced hot air furnaces that were "twinned" by a "heating professional" that obviously knew way less than I did. The duct work for supply from the two furnaces was in parallel, as was the duct work for the return. The the single thermostat turned on both furnaces in parallel too. But the blowers ran based on the temperature of the air in the individual plenums. So one would turn on first. And that would blow the other one backwards. When that plenum got hot enough (soon after), that blower was already spinning backwards and powering it on to run in the forward direction meant those motors lasted only a couple of months. IIRC, they were about 1/2 horsepower. They do not like being started when already spinning in the other direction.

newagedawn

which blower motor, in the air handler or condenser?

njtommy

If it's an ecm or an x13 motor and they keep burning up sounds like you have a high static pressure problem/ not enough return air.

Big Ed_4

We know something else is wrong .. Is it an standard motor or one with but in electronics we call a ECM motor ?

On an standard motor the first thing you check the capacitor , Good practice to change both .. And I always change the wheel and be done with it .

Things I would check since this is an running problem ...

1) Voltage , too low of voltage will burn out anything ..

2) Is it the correct motor for the unit ?

3) Is the motor getting wet ? condensation drainage issues..

4) check the amp draw on the motor

5) Is the duct work size properly

ChrisJ

First thing I'd check is the supply side static pressure.

Interesting video on the subject : https://youtu.be/Dr3trVcFiI0

I'd also want to see the total system static pressure, but the supply side would be my first concern.

newagedawn

could be a short in a wire somewhere

j a_2

Wondering how this was fixed,or was it....How new is the system and the duct work?...Any recent changes to the system?..How about posting a picture, that always help...When it does work how is it?...

jumper

>>The voltage supplied to the blower exceeds the motor nameplate rating by more than 10%.<<

too common. 220≠240 & so on

j a_2

II once new this real young fresh out of A and P school mechanic with his new aircraft license,who got his first job at a small airfield in Southen Florida...One of his first simple tasks was to replace a tail light on a Cessna 152, or similar...SO he went to the stock room and got a bulb,simple correct,then proceeded to replace it,still simple correct...Powed up the battery system and wam the bulb blew, so he went back and got another one,then another one...whoops no more bulbs in stock, so ordered one...Boss calls up and says there are 3 in stock..I said yup, all bad,go figure...Screams at me, says get a meter out and check power, I did, Holly crap it's 24 volts not 12 volts...1978, bulbs cost 68.00 ea. My pay 6.00 PER HOUR.Man did I learn how to use a meter real fast.

BobC

Many moons ago i walked by a new technicians bench with a box of 100ea 0.005 amp fuses and s Simpson 260 meter on it. I noticed about a dozen fuses on the bench and they were all open.

A minute later this new tech walked up to the bench and told me that brand new fuses were bad right out of the package. I asked him what range are you using on the Simpson? He said the x1 ohms range, the meter jerks some but the fuses are all open.

These were military fuses that cost about $8 ea in the early 70's and they were not easy to get in quantity. I told him to go get a 1 amp meter out of the equipment cabinet and measure the resistance of that 1 amp meter. He did so and the ohmmeter indicated zero ohms but the ammeter indicated over 300 milliamps.
He looked at me with very wide eyes and said I didn't know, I told him you do now. i also told him to use the x10,000 range on the ohmmeter.

We all **** up, the key is not to make that particular mistake again. He worked for us for 20 years and became one of our better techs.

Bob

j a_2

I loved the Simpson meters...

ChrisJ

j a said:

I loved the Simpson meters...

I still use one. A 7P.

j a_2

Yes I think there the top of the line...Back in my airline days that's pretty much all we used....At that time not sure if Simpson had digital meters, so on some resistance checks we had to use the fluke...

j a_2

@ChrisJ ...We agreed, that don't happen, a lot.....lol....

ChrisJ

j a said:

@ChrisJ ...We agreed, that don't happen, a lot.....lol....

My main pieces of test equipment are :

Fluke 179 DMM
Simpson 260 7P
Tektronix 100MHz dual channel scope with 10x probes. Can't remember the model.

j a_2

Those coming into certain trades out here best know how to use a meter....Well,then again you can just replace all the parts,and charge the unknowing customer...

ChrisJ

j a said:

Those coming into certain trades out here best know how to use a meter....Well,then again you can just replace all the parts,and charge the unknowing customer...

If I was in the trade, I'd probably want a hand held scope.
It's just too useful to not have in my opinion. It's like anything else, once you get used to having one, you don't want to be without.

newagedawn

sounds like a short to me

ChrisJ

newagedawn said:

sounds like a short to me

Why?

BobC

I still have a couple of Simpson 260 series 3, I bought the oldest one in 1961 from Radio Shack on Commonwealth Ave when I was just about to go into high school. I must have saved for 6-8 months to buy that .

I preferred the Simpsons to the Tripplet's because the polarity reversing switch switched the polarity of the test leads and that was the easiest way to check a transformer for a shorted turn. Switching the polarity would cause the needle to kick and the amount of kick was a good indication of the inductance you were looking at. A transformer, or motor, with a shorted turn has very little inductance.

I think Simpson was the only multimeter that switched polarity like that.

Bob

j a_2

ChrisJ said:

newagedawn said:

sounds like a short to me

Why?

Good question?

Mark Eatherton

Blower motors are very susceptible to overloading. If the blower is undersized, it's working too hard. If its correctly sized, it may be trying to move too much air. You may need to adjust a damper and choke air flow.

Short cycling is also a known killer of any electric motorized device. The hardest thing you can do to any piece of equipment is to start it....

ME

JUGHNE

This has become an interesting coffee shop chat of preaching to the choir. The OP has not been back.
Just another thought is that even if the motor rotation is correct, it is possible to put the wheel on backwards. (If the set screw is an allen head that can be reached thru the wheel blades.)

Good general discussion though, IMO.

HVACNUT

> @JUGHNE said:
> This has become an interesting coffee shop chat of preaching to the choir. The OP has not been back.

>> I think he's stuck in the attic. His wife's never been happier.

JUGHNE

This isn't ChrisJ in the attic is it??

unclejohn

Call the manufacturer's custmer service line and tell them you have replaced 3 motors under warranty and want help.

j a_2

unclejohn said:

Call the manufacturer's custmer service line and tell them you have replaced 3 motors under warranty and want help.

I would venture to guess it has nothing to do with the manufacture of the motors...but that's jmo

unclejohn

Then your guess would be right. I'm talking about the manufacturer of the equipment. Everyone else knew that. But thats jmo.