How could an AC motor do this?
 

The blower motor on my furncae is dying...AGAIN. Once in a while--it refuses to start, and I have to spin the pulley a BIt--and it then will. It is a belt-drive, 1/3 HP normal split-phase motor. This happened before, about 8 or 9 years ago. I have a new one on the way. HOW can a motor do this--it seems to spin freely..

Is there a motor start capacitor that's failed?

^^^ Like he said.

Chip

A split phase motor has a start and run winding. The stationary start switch, might have bad contacts, or the centrifugal actuator might be gummed up and holding the start contacts open.
If the motor has sleeve bearings, they could be causing an uneven air gap. Because of belt tension, they get worn in one spot.
Instead of trying to trouble shoot this problem, replacement is the best policy.

These are good ideas ! I use to have a belt drive in my heater but there were like 20 sets of bushings in a box, and if the belt was a little too loose it would sequel something awful.... After our second year in this house I replaced the motor with a direct drive motor, had the shaft turned down the meet with the motor shaft and got a direct coupling between them. Lasted 3 years, then bushing problems in the motor, replaced it, ran 2 more years..... Then got a similar motor for outside use, sealed with ball bearings.... 6 years now I think and it runs perfect... Replaced all the stupid bushings on the squirrel cage fan with ball bearings too.... That has been trouble free 6 years too..... The belt bushing thing I replaced bushings 2X a winter..... Sucky design.....

RCA2000 If you look at your squirrel cage you will or should have screw holes in 3 places spaced out. There is a motor belly band that you can get at Grainger and it will hold a motor there, then get a coupling, and reversible motor, and you can end your motor problems.....

SOrry--I have been out most of the day, DIalysis then Jungle Jims, Krogers and one of my thrift stores too. Just got back here.

Anyway...NO this motor does NOT have any starting aids. no start cpaacitors, run capacitors or such. A plain--old split-phase motor on a nearly 40 year old oil furnace. The blower dies in 2008, and I put in a new one from Grainger, along with the "fan/limit" switch--it had gotten to where the blower would just run...and run...and run.. The bearings in the blower had gone bad--and I did replace them--but evidently too late. The cage began to "come apart', making a LOT of noise and straining the then-new motor(this motor). SO in December of that year---I put in a Dayton (IIRC) replacement from Grainger. Since then(until a couple of months or so ago..) all was fine.

A few months ago..It began to get a LOT "louder" when it came on, making a kind of "bumping noise". At first..I thought it might be because the blower was not really tight in the furnace(It was not a "perfect fit" for the floor of the furance--but WAS a perfect fit for the opening it goes into). SO I "rigged it", to make it much more stable, and not able to move any. This did NOT help.

THen, a few weeks ago, The burner came on like usual--but i did NOT seem to hear the blower start, and thought I heard a humming noise. The noise stopped, than a minute or less began again. Then, the burner kicked off, since the blower was not runnng , it kicked off on the over-limit switch. Then, I heard the hum again. NOW--I figured I KNEW what was going on.

I went to the basement, checked to see if the blower had "locked up", or gotten stiff, I had turned off the power, just in case. The motor and blower BOTH seemed to turn freely with my hand. The blower did NOT seem in any way to have any "play" n its shaft either. SO, I reapplied power...and the blower took OFF!! I thought at first...maybe I imagined all of this' I turned the power back off--then on again, waiting till the blower had come to a full stop. It started again, and again and again. . Several times, it started every time. So, I closed the blower door, and kind of "forgot about it", figuring maybe i had imagined the whole thing !!

Till 2 nights ago. It did this once again. THIS time..I did NOT turn off the power, and when it tried to start again, and began to hum, I LIGHTLY, spun the motor pulley. Once again, It took off and stayed running. However it DID seem to "bump" to a start", but once there--ran fine. This happened again last night. I spun the blower while it was in protect, and a bit later, the reset clicked the motor back on--and it again bumped to the run mode--and has been there since.


I know the motor is going. I got a NEW one on the way from Ebay, $60 INCLUDING shipping. This is quite cheaper than I can get it at grainger IF they would let me buy one.(The last time I did--i was working for NOrthgate., and they had an account with them ..you all know how that turned out).

But i do NOT really understand..just WHY it seems to be that if the motor "comes to a stop in a certain place" it will NOT start itself, ....BUT if i either spin it from that place it WILL start on its own, or if it is trying and I VERY lightly turn the pulley...it will take off...and the work for a while...before it does this again... It would seem to me if it was a bearing problem--it would NOT be easy to turn...but it IS.

Try hitting it, and not turning it, maybe a loose connection and you are moving it enough for the connection to make, and then the vibration keeps it going.....

I got my last motor off ebay too, $60. with shipping, sealed outside use ball bearing motor..... And yah it sucks you have to run a scam to buy at grainger.....

It is a sleeve bearing motor. Dayton #6K778G.

I wonder if I CAUSED this, by allowing that motor to run with that bad blower, for maybe 9 months or so, before I replaced it? After all motors used to last a LOT longer than about 6 years. Often, they had an indefinite lifespan...

My sleeve motors use to run for a while, then bind up somehow, then cool off and then they would start up and run a while again.... You could see the pitted shaft, and bushing. Even when I took em apart in the summers, they would only last a few years... "Go Ball Bearing, you'll never go back!"

Well...the motor did it AGAIN a bit ago. I had to go down and start it manually and THIS time--it needed a bit MORE turning to get going. I do NOT think it is going to make it till sometime next week--so I have turned the blower to 'always on", for now. I do not like doing that--but it seems to run ok once started---and it will keep the house warm this way--though I know it will use a lot of power to do so. I am just getting afraid that sometime VERY soon--it will REFUSE to start--no matter what I do. Prayerfully...it will only be for a few days...

Shit capacitors..... ??????

SR

Worn brushes or bad brush springs maybe?

No brushes, no caps. Simple split phase 1/3 HP induction motor. NOT PSC either--simple split phase. It seems to "bind" when it stops sometimes. SO--it will run till I get the new one....or it dies altogether...

These motors have no brushes, slip rings, nothing.... I think once the bushing goes bad, they get hotter than designed for and the shaft expands and binds up. In addition to this, the coil seems to get hot as well, and it looses power to turn, stops, then gets more hot. After it cools a while it will run again for a while until it begins the binding process again.... I had several do it, including a window fan, where that one acts the same.... Both motors have only a coil and solid core armature, no wires, no slip rings, brushes....

Buying products at Grainger.
 

Grainger was restricting the purchasing of their items to only account holders.
Now, because of the economy, they're selling to the general public. They're even advertising on billboards and the radio. Their prices are really high and the shipping higher.
Their regular accounts get a better price.

I use to go to Grainger just because they had stuff like furnace motors, A/C stuff, oil for compressors, relays for my heater.... And their website was pretty dam good, lots of specs, lots of parts I didn't know where else to get..... But now there is ebay, so they can take their "we only sell to commercial" and stick it ! I haven't been there in over 5 years....

Compared to most of our locally-owned Plumbing-Heating and Electrical Distributors, they ARE a rip-off with limited choice and a bad attitude toward cash customers.:thumbsdn:

Well...day 4 with the old motor still churning away...I think it will make it to the end. It WILL cost me some money--but it is better than NO HEAT. The continuous blower does NOT seem to make it harder to heat the house--either.

All it's doing is moving the already heated air through the home. It probably isn't that bad of an idea.
This has been a really brutal winter so far. It's affecting the entire country.

New motor is here. Turns out to have BALL bearings, lubricated for 10 YEARS !! Will install it in a little while.

I've bought direct from Grainger's and also from them on line. If you have plastic, they're fine with that. But many parts are available from multiple sources on line and if you're not desperate to have "it" that same day you can sometimes find a deal.

Correct!, There are many good sources online if you have the time to wait. I have also found Amazon to be a good source as well, especially for tools. I needed several metric taps over the years, and local sources suck hard, I found a few tools stores out of Texass that ship fast, good quality tools, they sell on Amazon, just like ebay.

Installed now. seems somewhat quieter, no "bumping noises" at startup. I put it back on "auto", so it will not run constantly anymore--BUT lowered the "cutoff temperature" of the blower switch--so it will run a bit longer, before shutting down after the burner does.

If all holds well--I will toss the old one in a few days. it is not really good for anything...BUT in an emergency, if this one dies of infant mortality--it WILL run once started by hand.

I've seen motors like that fitted with a shaft coupler connected to a large bolt. Take that and use a nut to hold on a grinding wheel and you've got a crude bench grinder....

I have been thinking of making another one of those, made one in my youth that was powered by a washing machine/dryer motor. However, I built a bench on wheels, mounted the motor on the lower panel, ran a proper-length belt through a rectangular hole in the top panel to a shaft/pulley/bolt-down sleeve bearing/dual shaft coupler assembly mounted on wood blocks to drive a grinding wheel and a wire brush wheel. I'm pretty sure it powered up with a light switch as well. No idea what became of it.

Century always built a little better motor. I see it's made in Mexico now.
I can't make out the nameplate. Are they part of Regal-Beloit?
At least, it's made in the western hemisphere.
That last GE blower motor, I installed, was made in India. :sigh:

I looked at the picture again and they are part of Regal-Beloit!
They wanted to buy the place I worked at for 33 years, but they wanted the Union to re-open the contract. The membership voted it down.
They're rather cut-throat. :thumbsdn: