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mcompton1973 10-06-2012 04:10 PM

Test control board/ hot wire blower motor
I have a Bryant Plus 90 Furnace circa 1997.
Blower does not work whether it is on "on" or "auto".
The AC compressor kicks in and works, heater kicks in and works....just no blower motor.

I have pulled the motor and had it tested. It checks out fine.
I have pulled and tested the is fine.
I replaced the thermostat (I had wanted a programmable one anyways...)
So I believe that means that my control board is bad. Thing is I dont know how to test it for sure. I also have read some references to "hot wiring" the blower motors. I could at least have heat tonight if I did that, if I knew which wire to connect to what

I have a fairly basic volt/ohm meter...but I am not an expert with it, but money wise I need to save whatever I can...looking at the control board, swapping it out doesn't scare me. It appears to be pretty straight forward, just dont get wires in wrong place, and make sure jumpers are set the same etc. I have a good aptitude...just not a lot of experience. There is a place in Omaha I can get a board ordered but I need to know how to test it to be sure...and how to hot wire it to last until I can get the part. (27 last night was a little chilly with no heat)

Any help would be appreciated. Thanks.

Big John Studd 10-06-2012 05:36 PM

I had identical symptoms. It was the board that was bad. I was able to repair the board and did not have to purchase a replacement. If you pull the ignition board and take a close look you might just spot the problem with your eyes. It was pretty obvious from visual inspection in my case. You can read my account here, which includes photos, what the problem was, etc.

Marty S. 10-07-2012 09:42 AM

One lead of the meter goes to the white wire(neutral) connection on the board from the blower and the other lead to the other colors,one at a time. If there's 120V then the motor is bad, if no 120V then it's the board.

Boards with flame proving circuits should always be replaced instead of repaired. Dumping raw gas in because that safety was compromised in some way would be a very,very bad thing.

mcompton1973 10-07-2012 09:19 PM

1 Attachment(s)
Well, I got the board pulled and there is NO DOUBT it is the board...I am not an electronics person, but I think they are resistors that are fried. I would say it needs the whole board replaced no chance of repairing it.

Looks like the replacement part # is 325878-751. My only problem is that with a different part number I have to make sure I get the wires in the right spot. I had made a diagram and took pictures, but now they will all be in different

I am hoping I can find the part locally at a decent price...but I dunno...

Here is the part, and I will keep you updated.

carmon 10-07-2012 09:26 PM

yep its pooched....:(:(:(:(:(

mcompton1973 10-07-2012 10:00 PM

so the next question is...
I see it on ebay and some online stores like 90-140 bucks...and then on other sites for like 250-300.

I cant see a difference...but am I missing something?

Nickhvactech 10-07-2012 10:07 PM

Number one is OEM.. A lot easier for install
Number two is NOT oem and will probably require following the schematic much closer
number three seems higher due to coming from Lennox themselves(guessing) seems exactly the same

Number one seems like the best choice
+100% satisfactory!!

carmon 10-07-2012 10:22 PM

get the oem one..... you have 30 seconds warranty as you are doing it yourself... get the proper part and it will last a long time

mcompton1973 10-07-2012 11:50 PM

Sounds good, I mailed on that OEM one...
Waiting to see if I can get it over nighted and shipped tomorrow.
I will keep you posted.

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