# Furnace won't fire after summer using AC



## cmiszczuk (Sep 28, 2015)

Hi.
I have a Trane TUX060C936B3 model furnace and now that the weather is cooling I discovered it won't fire for heat. A/C worked this summer, but we didn't have to run it all that often.

Details:
-turn on heat at thermostat and hear the click...but nothing happens at the furnace, no clicks no noise of any kind.  power and gas are fine.  fan comes on when switched from auto to on.

-after a day or 2 of running the A/C there was water on the floor around the furnace.  It was coming from the hot side drain, not the cool side drain.

-was getting 3 flashes which is a pressure switch problem according to the sticker on the controller.  

-pulled the vacuum lines off the pressure switch and water dripped out!!

-reset ignitor switch with vacuum line off the pressure switch and this time the ventor motor fires up...but nothing else.  now light on controller flashing normally.

-drained water out of the pressure switch and vacuum lines and now the ventor motor comes on, ignitor clicks, see the orange glow but the burner won't fire.  cycles through this 3 times and then fans come on and light flashes 2 times indicating 'system lockout (no flame) check line poloarity".

-there was a bit of water in the ignitor from the vacuum lines... so last night i left the vacuum line off hoping anything still in there would evaporate.  it's clicking on so it's getting enough pressure in there but it's not sending gas to the burner.

My brother was over, handier than i am and suggests that if there's still water in there that could be causing the problem.  He things that the A/C drainage had backed up and water came down through the system, but we couldn't get at the drain because the pipe is plastic with no clamps...it will have to be cut and investigated before we consider running the A/C again next year but in the meantime I just need heat! 

Any ideas beyond letting water evap in the ignitor?(is that the right term? it's the little box that has the on / off switch that sends the gas to the burners).  Forgive my noobiness.

Thanks


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## nealtw (Sep 29, 2015)

Welcome to the site, there are people here that know this stuff, hopefully they will be along soon


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## DFBonnett (Sep 29, 2015)

That happened here a few years back. Gas valve failed.


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## cmiszczuk (Sep 30, 2015)

DFBonnett said:


> That happened here a few years back. Gas valve failed.


 
I'm hoping it's simple like that..it's getting to be cold and I need to get this working.  How can I test if that's the problem for sure?


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## kok328 (Sep 30, 2015)

Possibly a bad thermocouple not signaling for the gas valve to open.


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## cmiszczuk (Oct 1, 2015)

kok328 said:


> Possibly a bad thermocouple not signaling for the gas valve to open.



Is there a way to test that other than replacing the whole gas valve unit?  thanks


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## nealtw (Oct 1, 2015)

I found this 
[ame]https://www.youtube.com/watch?v=suen7QlJl4o[/ame]


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## cmiszczuk (Oct 2, 2015)

Thanks for the help but we got it working last night.  We measured pressure on the pressure switch and everything looked good..then we pulled the condensate drain pan and flushed it and when we put that back on it fired up.  Was a simple fix afterall.


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## WyrTwister (Oct 5, 2015)

Sounds like you got the drain working .  And let the rest of the system dry out ?

God bless
Wyr


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## cmiszczuk (Oct 5, 2015)

WyrTwister said:


> Sounds like you got the drain working .  And let the rest of the system dry out ?
> 
> God bless
> Wyr



I think so. I didn't get to fixing the end of the drain hose and after a weekend of working it didn't fire this morning.  I've now fixed the restriction and so far so good.  

Will have to look at the ac drainage situation before firing that beast up next year.


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## cmiszczuk (Oct 7, 2015)

Update:  Still having problems.  Every morning I find excess water in the drain hose and have to flush them and empty the condensate pan, wait 30 mins or so to get it to fire.  I've been working on getting the drain hose on a consistent downward slope from the condensate pan to the floor drain but each day it works until presumably enough condensate builds up and it ceases to fire and I get the 2 flashing code indicating no heat.  

This is getting frustrated as the drain hose is better than the one that has worked since we bought the house a year ago...at least in terms of flowing free without kinks and obstructions.

But then all I need to do is empty all the water out and it refires...so it seem sto be a drain issue...or a water issue.


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## nealtw (Oct 7, 2015)

Can you mchanges the hose out for hard pipe, that won't sag.


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## cmiszczuk (Oct 9, 2015)

New detail.  Still not working right even after getting the drain pipe sorted out...but if I tap the gas valve as it's about to fire it works.   This tells me the gas valve is sticking, perhaps due to the moisture that originally got in there.  

Can that be cleaned or is it a replacement only part?

Thanks


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## cmiszczuk (Oct 19, 2015)

Update: It's the gas valve.  It sticks and doesn't allow gas to pass through. Tapping sometimes frees it up but i'll be replacing today.


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