# Goodman GMPN080



## andyman (Jan 12, 2005)

Hello,
I have a Goodman GMPN080 furnace.
I have an intermittent problem.
The control board flashes non-stop indicating a reverse polarity on thje transformer.
After it sets for about 2 hours with the breaker turned off it starts right up.
I have checked the transformer for the proper voltage and it has 120v AC in and 24v DC out just like it is supposed to.
Is there some sort of thermal overload that is internal to the transformer that may cause this or is there something like this on the control board?????
When it fires back up it runs fine.
Any help will be greatly appreciated.
Thanks,
Andy


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## HVAC Doc (Apr 1, 2004)

Since it runs just fine for awhile and doesn't isntantly lock out on reverse polarity, I would be leaning toward a defective control board.


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## andyman (Jan 12, 2005)

Thanks Doc,
I will get one and give it a try.
I appreciate your help
Andy :Thumbs:


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## bigdogx01 (Feb 5, 2005)

CHeck for a good ground. GRound rod 8-10 feet in the ground


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## andyman (Jan 12, 2005)

THanks BigDog.
We installed a new board and it worked fine.
THen the flame detector went bad.
We cleaned it and it worked but we went ahead and replaced it anyway, it is still under warrantee.
I am starting to think the "good deal" on my furnace wasn't sucha good deal.
My uncle is having the same type of troubles with his Goodman.
THe power around here has been on and off a lot so I am not sure if that has anything to do with it.
THanks again,
Andy


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## NickTech (Feb 13, 2005)

The polarity of a transformer is based on the wiring of the line side. If you are to change polarity then do it with 120v wiring. Make sure line to ground is 120v. and N (white) to ground is zero. with the polarity established you shouldn't have the same problem. Your flame sensor failure also may be a result of wrong polarity. Since the dc micro amps carried thru the flame needs to be grounded back the module (thus proving flame), a reversed polarity on the module or ground will cause your problem. Now since you are having an issue with the power in your area, the furnace wiring may not be the problem at all. You maybe having a grounding, or polarity reversal at the "pole". Have your power co. Check it out for you. Don't dismiss the chance that your furnace module can be defective for a number of reasons. Goodmans are the cheapest of furnaces. If a carrier is a cadillac, then a goodman is a Yugo.
:Thumbs:


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