Intertherm(Nordyne) gas furnace not working :(

Old 10-03-11, 02:50 PM
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Intertherm(Nordyne) gas furnace not working :(

and I've googled and googled and am at the end of my rope. Help please. Here's the story so far:

I think it is a mid efficiency one. Per diagnostic code, "pressure switch stuck on close". Have done quite a bit of trouble shooting, but not getting anywhere. Now nothing happens at all when I turn the thermostat to heat. When this first started a few days ago, I very gently blew through the rubber hose that connects to the pressure switch and for good measure gently blew through the other end of it where it connects to a metal nipple on the surface of the furnace "body". It actually did start up and I had to lower the temp. since it was getting too hot. I was all happy, but then the next morning noticed no heat again so was no longer all happy. It did again turn on by "itself" the following day, but nothing since then. Yesterday, removed the pressure switch and noticed some water came out of it(during the summer the humidifier backed up and the water was probably from that). I shook it out and let it dry out for half a day and put it back into the furnace. Still same code showing. I took the switch off again and blew through the plastic nipple and can hear the diaphragm move and had it checked at a local parts store and they did a meter reading or something and said it is working. I then turned off the furnace again and removed the wire that goes into the pressure switch and put the power back on, bypassed the power off by pressing that whatever one calls it switch(only did it for a few seconds since not good to be bypassing the pressure switch) and the draft inducer did kick in(saw the fan that is visible spin very robustly and heard it so assume that the draft inducer is working). I haven't checked the flue yet since it seems like it is not going to be easy to disconnect that and not sure if any not good gases will be left in there(I would think not since the furnace has only been used a bit so far this year). Is that about there probably not being any not so good gases left in the unit/flue? The only other thing I can think of is that the circuit board is somehow not good(just surprised about that since would think other things that did work wouldn't work if it were a circuit board problem) or there is some kind of "lock down" that needs to be reset since it seems the problem has to be somewhere in the beginning of this whole heating cycle since if it were later on, there would be some other diagnostic code and think this pressure switch code wouldn't show up since from my understanding it's function is mainly at the beginning of the heat cycle(pressure switch usually on open, furnace "senses" that, which lets the draft inducer do its thing, which then closes the pressure switch, and then the rest of the sequence as far as I understand things, but maybe I am not understanding correctly). I just went back down againnnnnnn to make sure again that the metal nipple that the rubber hose from the pressure switch connects to isn't clogged up with rust(think it probably also got wet since the housing of it got wet from that humidifier incident). I put a thin, firm metal wire(power to furnace off, obviously) through it far down and then hit something solid which I don't think is an obstruction since it really feels super solid. Well, that is about it, I think. Oh no, I did forget something. When I turn the thermostat fan to "on", the fan does run so I assume that is the air blower(moves air through for heat and AC) which seems to be working. Hope someone can enlighten me since not a good time financially to be buying a new furnace(would end up having to do that since it is 14 years old and I know how much just those service calls are and how much having a part replaced is if not done by one's self and already put a fair amount of money into this furnace/air unit part already, but really think there is a relatively simple fix that I can do myself or maybe I am wrong). Helpppppppppp, pleassssssssseeeeeeeeeee.

Old 10-03-11, 03:50 PM
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model number would help.... is the flue metal or pvc. Having water in the switch it should really be replaced. Water should not get in there unless you have a 90% eff. furnace that uses PVC flues. IF you do have this then you need to locate the drain trap and clean it out, also you need to clean out all the hoses and drains in the furnace. If water was in the press switch then you need to replace it. Stuck closed is a sign of a bad switch. Stuck open would be a sign of a blocked flue or vent or a bad switch.

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