# Armstrong Air Ultra V Tech 80 problem... wont stay on :(



## Kassy (Nov 19, 2011)

Hey guys,
So, I'm sure there might be a post on here in regards to what I'm about to request, but if there is, I probably wont understand it b/c I'm new to doing actual hands on T/S with my HVAC. Sooo... here's my problem: When I start it up, it turns on briefly, the flames ignite and start to heat up the inside of the HVAC, but then they shut off. It does this sever times and sometimes the air start to come out of the vents for a brief moment, but then it cuts off. I have to go to the control unit and turn it from 'Heat' to 'Off' to 'Cool' and back to 'Heat' to get it to cut back on. Then, it just repeats the previous steps. It's been doing this off and on for a few months, but for the last few days, it's been doing it non-stop and I can't heat up my house  I have an electronics background, so I'm pretty decent with schematics, but the one on this thing is a bit confusing (and it doesn't help that i'm TOTALLY unfamiluar with the interworkings of an HVAC unit).... Sooooooo.... any suggestions for starting points? I will answer any and all questions that I can as soon as I can. 

THanks for all the hopefully potential help to come!

Kassy

P.s. I did notice that the red light on the board at one time was pulsing about 8 or 9 times, then stopped and started again. IDK if this is typical or not :-/


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## bob22 (May 28, 2008)

What does the trouble code light menu on the furnace indicate for the flashing codes?
Likely not the problem but when was the filter(s) replaced last? Should be about once a month for most.


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## yuri (Nov 29, 2008)

-find the diag code for those flashes and count them CAREFULLY, may be on the back of the fan compartment door or other door or in the owners manual

- flame sensor may need cleaning. sits in front of one of the burners and looks like one of these. clean it with clean steel wool or fine emory paper


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## Kassy (Nov 19, 2011)

Hey guys. Thanks for the quick replies. IDK where the codes are. I have looked all over this thing and don't see them, but I came across a post on the selfhelpforum.com or something of the sort that talked about a possible clog in the 18" rubber hose that is about 1/4" in diamiter. I took it off, ran a wire through it and it's currently up and running. If it keeps acting up later, then I will take some wool to the sensor. I was actually looking at that right before it cut on, and was thinking about trying to clean it as well. If it shuts off and stays off before it warms up then I will see what I can do about it! THank you 2 again for your quick responses


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## yuri (Nov 29, 2008)

the sensor should be cleaned once a year anyway.


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## Marty S. (Oct 31, 2009)

That one has a smart valve doesn't it? Clean the sensor as yuri said and if it acts up again the gas valve should be the prime suspect.


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## yuri (Nov 29, 2008)

if it has a Smart Valve sv85*** DO NOT try clean the flame sensor as you have to remove the whole pilot burner dis-assemble it and it is VERY fragile. you can clean it but it is very easy to break and I have not had problems with the sensor getting dirty on them for some reason. mostly the valve is the problem.


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## biggles (Jan 1, 2008)

you need to shut the service switch on the side of the furnace OFF to clear the last diagnostic.... with the stat not calling.remove the stat and jump R to W for solid call from the stat then put the service switch back up and lets hear back on that sequence of starting...


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## Kassy (Nov 19, 2011)

biggles said:


> you need to shut the service switch on the side of the furnace OFF to clear the last diagnostic.... with the stat not calling.remove the stat and jump R to W for solid call from the stat then put the service switch back up and lets hear back on that sequence of starting...


I hit the switch when I was working on it... the light stopped blinking, but it was blinking again when I got home. I left for an hour and it heated up to the designated temp of 74. I turned it up to 76 to see what would happen. When I looked at the light, it was blinking 8 times, then would stop for a couple seconds and blink 8 times again. It kept doing that. The unit didn't turn on when I turned the heat up, so I had to turn it off from the control unit, then back to heat and it started right up and is still running. It seems like once it hits its designated temp, it shuts off and wont turn back on once it's cools down a little bit.


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## Doc Holliday (Mar 12, 2011)

Pull the stat cover off to expose control wiring. Jump the R to the W and see if the unit heats up and stays running until you remove the wire. Then try it again, leaving the jumper wire in place for about ten to fifteen minutes at a time to see if the unit stays lit. 

I no codes then and the unit runs fine, replace your thermostat.


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## Doc Holliday (Mar 12, 2011)

You can remove the stat from the system completely by removing the wire on the R terminal on the control board in the furnace. That is your 24 control voltage. 

Then you can jump R to W on the board itself.


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## samswenson (Nov 26, 2011)

*Solved!*

Kassy,

I was having the same issue you have, with the exact same furnace, for years now.

It turned out to be the flame sensor like Yuri said previously! To the normal home owner (me for example) it is hard to tell if the sensor needs to be cleaned until you pull it out. That is partly because the area that needs to be cleaned is hidden from view until it is pulled out.

Once pulled out (make sure to unscrew the one screw, and unplug the wire that is attached, easily done by pulling on the rubber covering), my sensor had a little buildup on it; white-ish deposits plus a little discoloration. This apparently, is enough to make the sensor not work.

I used an emory board (nail file) to remove the buildup and wiped it clean with a dry cloth. I put it back in and it worked!

Yuri, thanks for the tip! Kassy I hope that helps a bit.:thumbup:


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## monongahela (Nov 11, 2012)

I cleaned my flame sensor and the gas heater works fine now. Thanks everyone. It was a pain to get off. Next time I will try cleaning it while it is still on.


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