Hi everyone,
First time on the site and hope someone can help. I have an armstrong ultra V advantage 93 gas furnace. We turned it on the other day and it would not start up. The diagnostic lights indicate that the pressure switch was in the closed position and wouldn't start. I took the hose off and blew and sucked simultaneously and heard it clicking inside the pressure switch. At this point the induction motor started and the pilot would lite but wouldn't start up. After three tries it stopped trying and the lights indicated that the ignition failed. Can anyone tell me what is going on. I hope that I don't have to call a repairman. Money is tight. Thank you in advance.

Sound like either your Thermostat not right, did u have an air-con, did that work.
Or is your thermo couple not working, so the system though you don't need the heat, either way it shoyldn't cost too much
Hope that help

I don't know that much about Armstrong but some things are the same on all furnaces.

Please explain one thing, you said the pilot would light, does that mean that a flame would light up or that the ignitor would glow? If you did not have a flame it is possible the gas valve is turned off, if you did have a flame on the pilot then never mind my answer. But if you will give us more info about how your furnace is suppose to work we may can help.

How many pressure swithces are on your furnace? Im guessing you saw the glow plug(orange glow) instead of a pilot. If you have two pressure switches, one will allow glow plug to burn, and other will allow gas valve to open. When you pulled the hose off the pressure switch, did you notice any water? If so, you may have plugged drain hoses, which will cause both pressure switches to act up.

Now, turn power off to furnace,, wait a few seconds, turn it back on and tell us exactly what happens... It should go like this,, thermostat calls for heat, draft inducer comes on for a predetermined amount of time(lets just say 15 to 30 seconds), then glow plug or spark ignition starts, then main burners lite, then after a predetermined amount of time(say between 30 seconds and a minute ) the blower comes on. Of course this is all assuming you don't have a pilot. Hope we can help. Lee.

how many pressure swithces are on your furnace? Im guessing you saw the glow plug(orange glow) instead of a pilot. If you have two pressure switches, one will allow glow plug to burn, and other will allow gas valve to open. When you pulled the hose off of the pressure switch, did you notice any water? If so, you may have plugged drain hoses, which will cause both pressure switches to act up.

Now, turn power off to furnace,,, wait a few seconds, turn it back on and tell us exactly what happens....It should go like this,,,,thermostat calls for heat, draft inducer comes on for a predetermined amount of time(lets just say 15 to 30 seconds), then glow plug or spark ignition starts, then main burners lite, then after a predetermined amount of time(say between 30 seconds and a minute ) the blower comes on. Of course this is all assuming you dont have a pilot. Hope we can help. Lee.

Yes the glow plug was glowing then I heard a click from the gas valve and flames ignited and shot into the furnace but when the glow plug stopped glowing the fire quit and nothing lit up in the furnace.

Sounds like your flame senser is dirty. The flame senser does exactly what it is called,, it senses the flame,, if burners lite, then go out once glow plug shuts down, then the flame senser is not sensing the flame and will shut off gas to burners. Flame senser is located on burner assembly, it will have one wire going to it,, only one, and is usually mounted with one screw.. the flame senser will either be straight, or L shaped,, it has a porcelin body where it mounts to burner assembly, and a metal rod that sits directly in the flame. Take it out, clean it with steel wool, sand cloth, fine sand paper , or any abbrasive material,, till it shines like new. Put it back in and let me know how it works. I've posted a pic of an average flame senser, but there are many different makes. Lee.

WOW VIC,that post confused me a little! Anyway,I agree, sounds like a dirty flame sensor,Armstrong uses a inermitent pilot, pilot lights,senses flame and then lights the main burners. Be really careful when removing the pilot assembly, the ignitor breaks really easy.

sounds like your flame senser is dirty. the flame senser does exactly what it is called,,,it senses the flame,,, if burners lite, then go out once glow plug shuts down, then the flame senser is not sensing the flame and will shut off gas to burners. flame senser is located on burner assembly, it will have one wire going to it,,,only one, and is usually mounted with one screw.. the flame senser will either be straight, or L shaped,,, it has a porcelin body where it mounts to burner assembly, and a metal rod that sits directly in the flame. Take it out, clean it with steel wool, sand cloth, fine sand paper , or any abbrasive material,,,till it shines like new. Put it back in and let me know how it works. ive posted a pic of an average flame senser, but there are many different makes. Lee.

I took the sensor out and sanded it but it still does same thing

Hi hvacservicetech_07
Basically that's what I trying to say like everyone else
The sensor most likely cost trouble, and is happening to older unit once or twice in their life time, when thing get to use for a long time, just like a wear and tare thing, I say change it will solve the problem,
But stronger advice do not try to do it yourself, unless you really for sure what are you doing, is a safety concern.

vic, you said you thought it was the thermocouple,, this unit does not have a thermoscouple, it has a flame senser, which rarely needs to be replaced, usually only needs cleaning,,

Iron, can you post a pic of the flame senser you cleaned? I just need to clear this up for my own purposes,, really curious as to what your flame senser looks like. Lee.

I agree, a piture would be helpful. I'm about 90% sure that Armstrong uses an intermittent pilot, older used a sparker and the newer stuff runs hot surface. I'm curious as well.

vic, you said you thought it was the thermocouple,,,this unit does not have a thermoscouple,, it has a flame senser, which rarely needs to be replaced, usually only needs cleaning,,,

Iron, can you post a pic of the flame senser you cleaned? I just need to clear this up for my own purposes,,,really curious as to what your flame senser looks like. Lee.

I can't post a pic but it is basically about a two inch metal rod about an eighth of an inch in diameter with about a half of an inch of ceramic at the top. It is right beside the glow plug and sticks down right in front of one of the burners. It has one screw holding it down. And one wire going to it on top.

Okay, you cleaned the right thing. As I said before, normally cleaning the flame senser does the trick, but I have seen them go bad.. So I suggest installing a new flame senser and see what happens. I have also seen bad flame senser wires, and also, it could be your control board has a problem. I would start with the flame senser itself, but your best bet would be to have an hvac tech in to trouble shoot the system, I understand times are tight, but they would be able to find and fix your problem in short order. Please let us know how you make out. Lee.