NuTone 8310 :fan motors keep burning up - Broan-NuTone N-769RF Combination Light Fan Exhaust Fan

This model has been discontinued but replacement motor assemblies are available. There is no off the shelf model that will fit in the existing housing. If you do not want to replace the housing then the motor assembly is the way to go.
You ca purchase the replacement from either site below:
http://www.centralvacuumstores.com/Bath-Vent-Fan/NuTone/Motor-Assembly/0696B000-Motor-Assembly.php

http://parts.broan-nutone.com/nutone/Shop?actn=quicksearch&searchtype=all&indextype=7&keyword=qt100l&Search.x=0&Search.y=0

The replacement motor is available for that fan model. The NuTone part number is the 0696B00. It can be purchase from these sites:

http://parts.broan-nutone.com/nutone/Shop?actn=quicksearch&searchtype=all&indextype=7&keyword=qt100l&Search.x=0&Search.y=0

http://www.centralvacuumstores.com/Bath-Vent-Fan/NuTone/Motor-Assembly/0696B000-Motor-Assembly.php

http://www.ventingdirect.com/nutone-0696b000-power-unit-assy-packaged/p431404?y=16&term=0696b000&x=41

this is a different fan anyway

Hi,
There are a couple of things that you will need to check. First, is there an obsrtuction in the vent pipe that will not allow the air to move out of the room. Verify that the fan is actually moving air and not just sitting there running. Most motor depend on air going over them to cool them.

The other thing would be to verify the voltage AT THE FAN. It would be best if you could do that while the fan is running. There may be a poor connection somewhere that is dropping the voltage to the fan motor which will make it run hot and burn it up. Find a bad connection can be difficult, but usually the connection will also be getting hot and have the telltale brown or black burn marks.

Heatman101

it may be that the bearings nead to be oiled, have you tried to spin it by pushing it with a pencil and see if it sticks or spins freely ?

need to blow it out with a air hose and oil it real good! but keep a eye on it to make sure it does not get hot! if it feels hot to touch replace the motor!

If you remove the motor, which usually isn't to difficult to do. I would recommend plugging it in to one of your electrical outlets to check it. There is a possibility that the wiring is messed up or the plug in the housing went bad. If the motor doesn't work you need a new motor if it does work then you could try replacing the plug in the housing. All these parts are still available.
Here is a motor finder for NuTone motors:
http://www.centralvacuumstores.com/nutone/fan-motor-main.php
Here is the manufacturer you can get parts from them:
http://nutone.com/

https://www.centralvacuumstores.com/nutone/fan-motor-ls-series.php

You should probably replace the heater motor. All the parts should still be available for you fan and it should only take a few minutes to change out.

place the push nut below the blower wheel. Don't bother with the top. The centripetal force tends to push the wheel down. The push nut in this position will prevent this.