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gulleyj 10-31-2012 09:13 PM

furnace blower won't come on
I have a Payne 376C downflow model furnace. I live in So California so my furnace operates only five months a year. Two years ago when I turned on the unit in October the heating component worked fine but the blower would not come on. The repairman I called in told me the blower was kaput and I needed a new furnace. After he left I bypassed the circuit board and found that the blower worked just fine. I pulled the circuit board and saw a dark solder spot, resoldered and reinstalled and the unit worked just fine all winter. Last year same thing: no blower, pulled circuit board, resoldered, good all winter. Today I turned on the furnace and guess what? Same thing. Assuming I find the solder bad again, what could be causing such? Why good on the last cold spring day and bad by the next fall? Should I just buy a new circuit board? ($200 - $300) MANY thanks.

JJboy 10-31-2012 09:38 PM

Check the amp draw on the blower motor.....also check if the motor is getting hot by touch.

ben's plumbing 10-31-2012 10:22 PM

yep ...agree...check for amp draw on motor....1 st place to start...ben sr

gulleyj 11-03-2012 12:35 PM

AMP draw lower than FLA. Now what?

how 11-03-2012 01:09 PM

Anoyher thought.
Where is the furnace in your home? Since your furnace is a downflow, I assume you have a rancher or groundfloor slab style home. I mention this because I have customers whose boards have a short lifespan (as well as other parts) because they use the furnace area because of limited space for drying wet clothes.
The worst are athletic clothes with a high sweat salt content.

yuri 11-03-2012 01:10 PM

do U have AC? if so then the board works in the summer and is subject to vibration etc. different relay on it for the heating fan and it sounds like U need a new board.

gulleyj 11-03-2012 01:43 PM

Don't have AC. Furnace is in attic and so not subject to moisture. Attic does get hot in summer because insulation is loose stuff lying on ceiling, not attached between rafters.

yuri 11-03-2012 01:46 PM

I suspect the board is bad. Depends on how good U are at soldering. The factory joints are machine done and I doubt a hand solder is as good unless you are an electronics guy with experience.

gulleyj 11-03-2012 02:32 PM

Guess I'll order a circuit board and I guess they're all NON-returnable?

yuri 11-03-2012 03:57 PM

YESS. to many inexperienced "techs" burn them out or zap them with static electricity and try claim warranty.

gulleyj 11-04-2012 09:53 AM

Thank you all for the help. Any last ideas about why the circuit board would go to bed working and wake up broken three years in a row?

yuri 11-04-2012 10:51 AM

Power surges, brownouts if you have heavy AC loads in your area. Thermal expansion contraction on that solder joint and the board as it is in a hotter environment in the summer.

gulleyj 11-04-2012 12:10 PM

Yuri, you are a generous man and I will gladly buy you a beer when you are in So Cal. At the risk of taking advantage of your kindness, I ask the following:

If my furnace only runs 1000 hrs/year, how long can I expect it to last? (It was installed in 1991.)

What brand of furnace would you recommend for its eventual replacement? (It is a 90,000 btu model serving a 2300 sf single-story house.)

Thanks again!

yuri 11-04-2012 03:47 PM

I would expect it to last 25 yrs at least in your climate. At that point some parts may be obsolete. Not all companies make downflows but Lennox and Carrier/Bryant/Payne probably still do. I prefer the Bryant in their series. Trane and York are good and after that the rest are about the same IMO.

gulleyj 11-11-2012 09:56 AM

continuing saga
Well I ordered a board and it arrived five days later just in time for our first temp. dip into the 40's. I installed the board and all components worked fine but now the furnace is cycling on and off continually and the blower seems to have no oomph. (I apologize for the ignorance implicit in this statement.) In my original test when I bypassed the circuit board the blower was fine. What's going on? THANKS.

Oh, and is the 'blower off' delay time just a matter of preference?

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