I have an electric furnacein my mobile home and it will every once in awhile hum like it is trying to turn on but won't unless I tap the blower cover.
The motor is a 'sleeved bearing' motor, not a sophisticated 'ball bearing' type motor. The bronze sleeves probably need lubrication. Some motors have no oil ports, and are referred to as 'permanently lubricated' motors. If you have oil ports, they will be approximately 1/16" in diameter near the top with little yellow plastic or gray pewter plugs in them. Remove the one plug you should be able to see and gently drop 30 drops of light weight oil into it.
The oil will slowly saturate the felt 'wick' that surrounds the sleeve bearing. The second oil port will probably be inaccessible with the blower installed inside the furnace and unless you are pretty handy, should be left for a pro. Unfortunately the oil port that is inaccessible is the bearing that carries virtually all the weight of the squirrel cage blower and is probably the culprit.
Another possibility is that the capacitor could be bad. With a bad capacitor, it probably wouldn't start on its own at ALL. Also the motor would overheat and would cycle on its internal winding thermostat.
Dec 23, 2014 |
Intertherm Air Conditioners