Furnace making a humming noise?

My gas furnace is making a humming noise every 20 minutes or so and it lasts for about 3 minutes, quits and then keeps repeating.

Also, when I go to turn the furnace on with the wall thermostat, it ignites (there's a flame), but the fan doesn't come on.

Could it be a fuse? The motor? Or..something else?


Thank you!!!

 

It sounds like the fan motor is trying to start but there is something wrong with it.

 

It could be the motor, the motor capacitor, or whatever device which sends power to the motor. If you can supply a make & model # of the furnace, maybe we can find a diagram online.

 

Manufacturer: Fedders

Model # : 080N2D

Serial #: KH892973

1/4 horse power motor

humming noise is coming from the blower. can manually spin the hamster wheel when it's off, but, not when it's on. It doesn't spin on it's own.

It ignites for heat and for A/C, the coils get cold, but blower isn't blowing out, just humming.

 

You coud try to test the motor wires with a volt-ohm meter and test in ohms, with the power off. It's possible problem with winding. Or motor's rotor going off center from the field of the motor, if bearing is bad. Or the capactior.

Capacitor should be about $10 or maybe less, so you could try to replace that.

But I doubt that is it, as giving it a shove should get it to spin. And since yours goes into that lock, it is probably the motor. A 1/4 horse should be relatively inexpensive, $65-100 I'd say depending on where you live and where you'd get it at, and if they sell you say a 3-speed (which will have like 7 wires coming out of it!) where you have the choice of which speed(s) to use. An OEM replacement from furnace shop will cost you more I am sure than going to a motor shop, or ordering online.

But if you go to the motor shop and take out your motor and take it there, they can test and verify. Taking out a blower motor is easy. 2 screws (ususally) easy. In case you do not know how, just ask here.

 

If you can't spin the blower wheel with the motor energized, your motor has had it. Time for a new one. Get a new capacitor with the motor.