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-   -   Wiring a replacement blower motor (http://www.diychatroom.com/f17/wiring-replacement-blower-motor-113559/)

bodtchboy 08-10-2011 02:20 AM

Wiring a replacement blower motor
 
I previously had an A.O. Smith 4 speed motor 1050 hp 115v. (part# 321p591) for the blower on my furnace. The wife noticed a bad smell and it stopped running. You can hear the electricity hum when it turns on, but it doesn't spin. The motor is also hot to the touch. I believe the bearings went bad on it. So I bought a replacement motor: GE, PSC, 1/3 HP, 1075 RPM, 115V, OPAO, 48YZ 2 speed.

The wires for the old motor looked like this: https://lh4.googleusercontent.com/-w...2/IMAG0031.jpg

The setup in the furnace looked like this: (Furnace wires to the left, motor wires to the right)

https://lh6.googleusercontent.com/-D...0/IMAG0023.jpg

The new motor has two capacitor wires (brown and brown/white), a white wire, Black wire (labeled as Hi (speed?)) and red wire (labeled as lo (speed?))

The old motor was not wired to a capacitor. I checked everywhere and could not find one. I assume that the old white wire labeled C was a capacitor wire, possibly built into the motor. I wired the brown, brown/white and white wires to the furnace white wire, the black to black and red to red. When I turn it on, I can hear the electric hum, but the blower is not spinning. Do I need a capacitor with this new motor? I'm a little frustrated that the technician at the parts store where I got the motor didn't tell me I need a capacitor with the new motor. I'm also questioning whether the replacement motor I got is a good replacement one for the old A.O Smith one, since the new motor is only a 2 speed instead of 4 speed. Any thoughts on this?

I've also noticed a green spark coming from the safety switch on the furnace when I push it in and it turns on or when I let go of it and it turns off. Is this normal?

JJboy 08-10-2011 03:00 AM

You need a capacitor for the new motor. Connect brown, brown/white to the capacitor.

bodtchboy 08-10-2011 12:01 PM

Thanks. So I'm curious, how was the old motor running without a capacitor? Do I need to run the white furnace wire labeled C from the circuit board to the capacitor, or just to the white wire on the motor?

Master of Cold 08-10-2011 12:30 PM

The cap will get the two brown wires.
The white wire will go to "c" on the board, and connects to white on the motor.

JJboy 08-10-2011 01:04 PM

You need connect Black to Black, White to White, Red to Blue,


Black - High speed
White - Line voltage return
Red connected to blue ( Med speed )
Blown - Blown/white to Capacitor

Take more pictures, old motor, new motor, furnace etc, control board

bodtchboy 08-10-2011 04:40 PM

Thanks everyone. Just found out the circuit board is bad. Is this part easy to replace? Something I can just plug together to the existing wires or do I need a repairman? Got a quote of $650 - $750 to replace the blower motor and the circuit board. I wish I had the money for that, but...

JJboy 08-10-2011 05:08 PM

Quote:

Originally Posted by bodtchboy (Post 704436)
Thanks everyone. Just found out the circuit board is bad. Is this part easy to replace? Something I can just plug together to the existing wires or do I need a repairman? Got a quote of $650 - $750 to replace the blower motor and the circuit board. I wish I had the money for that, but...


We can help you fix this issue. :thumbsup:

Master of Cold 08-10-2011 05:38 PM

You can get around the board for cooling purposes. You will need a 24 volt relay.

newtech 08-10-2011 06:03 PM

Quote:

Originally Posted by Master of Cold (Post 704484)
You will need a 24 volt relay.


Not if you wire the fan direct.. No extra parts needed.

Master of Cold 08-10-2011 06:05 PM

Why on earth would you do that??

newtech 08-10-2011 06:16 PM

Quote:

Originally Posted by Master of Cold (Post 704515)
Why on earth would you do that??

Isn't this a temp fix??? So what if the fan runs all the time until he can get a new board. He will have cooling until he can get the proper part...

A relay here or a relay there is Hackery....:yes:

Master of Cold 08-10-2011 06:25 PM

It will result in higher humidity levels.

newtech 08-10-2011 06:33 PM

Quote:

Originally Posted by Master of Cold (Post 704532)
It will result in higher humidity levels.


It will.. To a certain extent... Noticible.... Probably not...

I say... Save your money and get the right part...

Especially if you heat your house with this furnace as well....

beenthere 08-10-2011 07:30 PM

Quote:

Originally Posted by Master of Cold (Post 704532)
It will result in higher humidity levels.


Yep, 3 to 5% increase in humidity. And could be a 30 to 35 dollar increase in the electric bill.

COLDIRON 08-11-2011 07:25 AM

Quote:

Originally Posted by newtech (Post 704541)
It will.. To a certain extent... Noticible.... Probably not...

I say... Save your money and get the right part...

Especially if you heat your house with this furnace as well....

"I don't need no stinking relays, the key word here is temporary he don't need to be fiddling around with relays and wiring them in the control circuit just wire the fan to constant run until the proper parts are purchased. :thumbsup::thumbsup::thumbsup:


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