Buzzing Sound From Central Air Unit - No Movement

[Jim Devereux]

When I turn on my central air/heat, I get a buzzing sound from the furnace unit. The outside AC unit and the gas heater seem to be working but the blower fan (below the inside furnace unit) will not move.

I removed the blower from the furnace unit and the blades spin very freely, no sound whatsoever. If I set the thermostat to "fan only" I still get a fairly loud electrical buzzing sound, like something is trying to come on, this is even with the blower physically removed from the unit.

I've done some looking on Google and seen other accounts similar to mine where the capacitor that serves the blower is bad. I'm not sure if I have that stated correctly, but any suggestions on how to proceed would be appreciated.

[Jim Devereux]

Ok but it's not just noise, the blower will not move.

[Red Neckerson]

[Art Todesco]

[Jim Devereux]

No, the buzzing is not coming from the blower. That was my first thought but I hear it even when the blower is disconnected.

I don't mean to say that the buzzing sound is abnormal -- I heard it even when everything worked. It's just the normal sound of my central air kicking on. Only now the blower does not turn.

So...

I'm assuming I have to check the blower motor to see if it's dead, and also check the capacitor.

[Art Todesco]

[Jim Devereux]

I checked the power leads that serve the blower motor and they do have power. I checked the 3 wires on the motor itself for continuity with the RX1 Ohm setting on the multimeter and got these results:

about 5 ohms between red and blue

infinity between white and red

infinity between white and blue

I'm not sure if these results mean that the motor is bad or not. I still can't find a capacitor anywhere, maybe this motor doesn't have one. I'm assuming it will look like a small tin can with three connectors on top.

The unit is a 'Trane' and was new in 1982. The motor is very diry with that spongy brown dust stuck into about every nook and cranny. I don't know how long these motors last, is 22 years the life span?

[HeatMan]

I think that furnace has gotten everything out of that blower it could. In other words, the motor is probably shot.

Replace the motor, but look at the condition of the furnace. Twenty-two years is near the end of the life expectancy of that furnace.