Originally Posted by Hog3loves
Jim, my 321 RSTS has the same symptoms and the service tech FINALLY pulled the furnace and circuit board. Same water/moisture issue as you had. How did it get wet in the first place and how did you ensure water intrusion doesn't happen again. Thanks.
I bought the unit used but it was at most a year old when I got it. Furnace worked correctly when we bought it so I assume this problem developed while I owned it. When I unhooked the furnace and spun it 90 degrees it looked like someone was inside of the heater already due to the way it was sealed up. Sloppy clear caulk around the control board access panel. However that may have also came from the factory that way.
I am pretty good with mechanics and figuring stuff out. But for the life of me I cant understand how any moisture could have gotten to where it was. That inside area where the circuit board lives is totally sealed. Where I found the moisture was directly under and in the middle of the circuit board and about the size of a quarter. Now the circuit board only sits like 1/8" above the bottom of the shroud but its positioned where it cant really move or bend down if you will.
But the fluid was definitely going from the bottom of the shroud and touching the bottom of the board right in the middle. There was green corrosion where this moisture was touching the board and I assume shorting the board out. I dont see any way that moisture could have gotten there but it was with no evidence of it running down and over or under any other part of the board.
I cleaned the board off and theres no burn marks or any other things that give me suspect that it wont work again. So I put it in the box the new one came out of and have it stashed away for if/when this new one goes out. Its worth a try to see if it works again. So I am completely baffled to how the moisture got in there. The exhaust is in the same area so maybe either moisture/condensation from it wicked down into there or maybe rain somehow got wicked in there. Thats my only guess and I have no solutions on how to stop it from happening again.