Furnace Blower Motor

Balance the fan witg fast drying PAINT. Just daub it on opposite the heavy spot. Don't attempt to run before the paint is dry.

I took one apart for a small fan and found that there was enough slop in the bolt holes that held the brackets for the rotor that it affected how the motor ran. I played with it a bit to get it perfectly centered and after that it ran well.
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I clean and re-oil my small fans at least once a year and have found that after reassembly if I whack the side of the shaft with a screwdriver, and repeat 90 degrees from the first whack, the bushings realign themselves quite nicely. Art

WD40 is NOT a lube, NOT a rust-proofer! Use WD40 for the ONE thing that it does, semi-well, displacing water. If you continue to use it on tools, it builds a brown hard-shell film that resists solvents, even itself. But NOT rust. And that film isn't any sort of lube. If you just gotta spray, use LPS 1, that leaves a non-conducting lube film. Still not a rust-proofer, use Boeshield or LPS 3 for storing outside tools.
The perfect thing for domestic fans and blowers is turbine oil, most any hardware store will have the Zoom Spout brand. Made for fans and swamp cooler pump motors. This is pure mineral oil, doesn't clog lube hole felts and doesn't leave residue. Made for the job.
As far as the O.P.s problem, if it's not got a starting cap and centrifugal switch, that eliminates the usual suspects. If it were mine and fairly easy to remove, I'd gen up a set of pigtails and hook it up to A.C. directly to see how it starts. If OK, then go back through the attached circuitry looking for a bad relay. A lot of the newer furnaces have diagnostics built-in to the controller boards, all you need to do is figure out how to use them. Mine has directions right inside the covers. Board even comes with shorting jumpers to get it into diagnostic mode. Readout is several blinking LEDs.
Stan
Stan

The standard process is to use a dish washer. Used on several series - from the old nail bangger to the models 32 and 33.
Speaking on 32 and 33 - anyone need one ? I might be able to get one of each.
32 is the office 5 level. 33 is the office 8 level.
The prior ones were backroom oil and ink messes but lasted years.
I suspect the WD-40 dissolved all of the oil and varnish rising it to 'tar'.
Martin

You should have put a smiley :-) after that. :-) ...lew...

If you need a smiley after that advice, it's already too late. ;-)

I still have (I think) a Mod 15 teletype stuck in my dads basement from the 1960s when I had a ham ticket and ran RTTY mostly.
I believe thats why I use the net......
I am the Sword of my Family and the Shield of my Nation. If sent, I will crush everything you have built, burn everything you love, and kill every one of you. (Hebrew quote)

What I was saying is that you could crank up the governors on the motor and get a faster baud rate. You would have to have another machine cranked up to the same rate. The late series model 28 you could crank up to about 110 baud before it would act up.
John

The dishwasher would do a good job to clean the stuff. I would use the hottest water and dish soap and then spray it with a coat of real light oil to keep it from getting surface rust. I rebuilt a bunch of 28 series machines including an ASR-28 I remember selling for 2500 bucks in the late 60's.
John

You might be able to detect out-of-round by measuring the baring areas on the shaft with a micrometer, although the anvil may be wider than the actual bearing widths.
If you were sure to reassemble the bearing supports in their original orientation, you might try loosening the screws that hold the supports a bit, with the motor running (frame held in a vise possibly), and slowly snug the bearing support screws/nuts with the motor running to see if there is any sign of binding.
Alternatively, you may be able to reorient the bearing supports 180 degrees if the motor is the type I'm thinking of.
As others have suggested, the assembled motor may benefit from a moderate thump (percussive alignment) to get the bearings to the best position in relationship to the shaft.
I find that many types of motors benefit from this procedure after reassembly.
The best solution may be to search surplus places for a new, similar, appliance or case cooling fan for future use if the rest of the furnace is in very good condition. Finally, a small squirrel cage/centrifugal blower could possibly be ducted to the area of the location where this fan motor mounts.
The most important caution would be to make sure the vent drafting is unaffected, if it is a gas furnace.

Doing slow scan on a TTY - sending snoopy pictures or Santa..... Then there was the Moon 'shot' picture...
Fun waiting for an hour.
Martin

When dish washed - we inserted it into a tank of oil.
Then into the oil tray - the bottom is a shallow cup. All of the pads are saturated and zero water left on anything.
If the 'item' can't be put into a tank of oil - then into a barrel of alcohol to absorb water.
Martin

Well, I brought the motor over to the Tech in Electrical Engineering, and the problem left him scratching his head as well. His thought was that there was a broken/separated bar in the rotor. At any rate it would seem to be unrepairable in the practical sense. I'll try unbalancing the fan slightly so it doesn't rest at the 'sour spot' and live with it for now. It's only used a few hours each week, and someone is always nearby to give the fan a nudge if needed. There'll be a 'new' furnace for the shop in next year's budget.
Thanks for all replies.
Pete

Well, I re-installed the blower assembly with a magnet on the fan to help keep it from stopping at the 'sour spot'(by 'unbalancing' it), and so far it's worked 100% of the time.
Of course it's just a temporary repair. Unless it works.
Pete

One of those itty bitty neodymium magnets?
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

A fairly itty bitty one, but not neodymium. It's on the 'I.D.' of the fan, so it can't escape.
Pete