Noisy Nortron furnace fan

[bmason3d]

Hi,
I have a Nortron forced-air electric furnace, model 21B20, installed on September 11, 2001 (a date that's hard to forget). It has been running well until last night, when it began making intermittent scrape/squeak noises. The (dirty) filter has been removed, and the cover taken off, and now the squeak only occurs for a few seconds during the torque of startup. I have set it for continuous run, with the cover off, and it is quiet. However, I can't leave it that way.
Since the motor runs freely and quietly, I am ruling out bearing problems, and have to assume that the turbine fan is slipping on the direct-drive motor shaft. Is this something I can fix myself, and, if so, how?
Thanks,
bmason3d

[HayZee518]

the turbine fan is a squirrel cage fan. if you can get at it, in between two blades you should be able to get in an allen set screw wrench. there's a grub screw in there. find the flat spot on the shaft and tighten the screw. a one eighth wrench will fit a 1/4-20 grub screw. use a drop of blue loctite if you can back out the screw on the screw's threads

[hvacwiz]

Originally Posted by HayZee518

use a drop of blue loctite if you can back out the screw on the screw's threads

I feel sorry for the person who would have to change the blower motor someday and he cant get the blower wheel off because someone put loctite on the set screw threads.

[bmason3d]

Thanks, HayZee518.
From what I can see, that would involve first removing the fan and motor assembly, to get in at the back of it. The assembly appears to be held in place by two small screws. Once those are removed, the fan assembly (expect to be heavy) will slide out.
Do I have the right idea? Please confirm.

BMason3D

[bmason3d]

After turning off the furnace at the main panel to inspect it, I found that the motor is trying to start, but can't pick up speed. I suppose that the problem is not a slipping fan after all, but rather dirt/dust buildup somewhere. Any quick suggestions?
BMason3D