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View Full Version : Very old furnace to new Blower motor wiring


Apofus
Dec 23, 2008, 05:17 PM
Hello,

I have an old GE furnace, from the 1960's I believe. Today the blower stopped working. I pulled the blower unit out and found the bearings destroyed on one side. I had no luck finding new bearings. So as a last resort a friend had an old furnace he had repalced with a blower motor that was working fine. I got it retrofitted in the furnace, however the old blower only had 2 wires going to the motor, the new motor has 5. I hooked up the white and black and it seemed to work fine initially. But sometimes the blower will begin to start and then stop. I assume there is more to the wiring than meets the eye. The new motor has white, black, red, blue and brown. I understand that the black, red and blue are for different speeds, but do I need to have the brown wire in the circuit somehow? If I hook the black, red or blue and the white to AC direct the blower works fine. Just seems to have problems starting in the furnace circuitry.
I realize this cannot be a permanent solution I just need to get through the Holidays and then we are looking for a new furnace.

Any help would be appreciated
Thanks

twinkiedooter
Dec 23, 2008, 05:58 PM
I hope someone comes along and gives you the proper wiring sequence before your house burns down from the blower being improperly wired up.

MarkwithaK
Dec 23, 2008, 06:45 PM
The brown wires are for a capacitor. If you do not have one wired in then what is likely happening is your motor is starting but pulling too many amps and shutting off on internal overload. You MUST have a capacitor and you MUST know exactly what size cap your motor needs.

MarkwithaK
Dec 23, 2008, 06:45 PM
An no, there is no way around this.

letmetellu
Dec 23, 2008, 06:51 PM
The capacitor information should be on the motor nomenclature plate. It will read something like 7.5uf 370 volts. Do not use these numbers they are just for you to get an idea of what you are looking for, and just like "markwithak" said use the exact one it calls for.

Apofus
Dec 23, 2008, 07:49 PM
There IS a capacitor wired on the blower there are 2 wires from it going to the inside of the motor. Then there is a brown wire coming out of the motor, what does that wire need to connect to? If anything... It seems that this capacitor may be a start capacitor a friend just told me it should be fine if I get the blower started and just leave it running. The furnace has a switch on the side to turn the fan on all the time. Would that be OK?

mygirlsdad77
Dec 23, 2008, 07:55 PM
What colored wires are hooked to the capacitor?

Apofus
Dec 23, 2008, 08:05 PM
It's hard to tell the color of the wires(dirty). However it looks like a brown and a brown with white dashes.

mygirlsdad77
Dec 23, 2008, 08:20 PM
This is tricky, Im not used to seeing three brown wires. I would suggest shutting furnace down, getting some temporary electric heaters, and staying warm with the electric heaters until you can find a motor that is compatible with your furnace. It can be very dangerous to mix and match parts on a heating system. I wish I had a better answer for you, but I've been around long enough to know, its better to be safe than sorry. I wouldn't want anyone to lose property or lives over a quick furnace fix. Take care.

MarkwithaK
Dec 23, 2008, 08:30 PM
MGD is correct. You shouldn't be trusting the safety and well being of yourself and your family just to save a couple bucks on a blower motor. Not to mention that it probably isn't compatible with your furnace.

The wiring you describe just doesn't add up.

KISS
Dec 23, 2008, 09:54 PM
See this thread:

https://www.askmehelpdesk.com/heating-air-conditioning/wiring-blower-motor-279465.html

That motor may need a start and a run capacitor. Hence the brown. Since you need a kick to get it going, the brown is more likely the start cap.