Help w/ Armstrong furnace

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Active Member
Apr 12, 2006
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I have an Armstrong Ultra V Tech 80 furnace that won't start. The trouble light flashes a code 3 as the problem. The manual gives a fault description as "pressure switch open with inducer on". What the heck does that mean in english? Sure would appreciate any help I can get. Thx.
Hello Cabinetsetc:
Yours is a high efficency furnace with a draft inducer which blows on a pressure switch to allow the gas valve to open. I don't see how that can be a problem unless the inducer motor is not running. If it is "on" but not running it is a problem.
Open the inducer and clean out any lint or dust that may have accumulated over the years, especially on the inducer fan (or impeller); put it back together and try it again. It also helps to wire brush and vacum the burners
and pilot tube for a better lighting cycle.
It may not have a standing pilot light but rather a spark ignitor or a hot surface ignitor. If it is a hot surface type, be very careful not to crack the ignitor or examine it with a magnifying glass for cracks. They are notorious for cracking after a year of two of heating to a glowing red and cooling down.
Please post back and let us know how it works out.
Glenn; The fan is definitely working. It cuts in and out on a regular basis but nothing else happens.There is a tube that goes from the fan motor (which I imagine is what they are calling the inducer) and goes to what looks like it could be a switch. It is a round thing against the panel that holds the fan. I think I would help you out a lot more if I got some pics of the whole thing. Then all I have to do is figure out a way to get them onto the site. I haven't figured out how to do that yet. Thanks for the help. I'll let you know what I find out.Rick
Glenn; I figured it out. It was the pressure switch that was faulty. Bought one and changed it and it works fine now. The other small space heaters with the control on the back is for back draft protection. Cleaned up the connections and they work fine. Thanks for all your help. When you start getting frustrated by a lack of knowledge it's nice to know that you have friends to turn to. Thx again.
PS: have been busy but the place is starting to take shape.
Hey Rick:
I'm glad it worked out for you. It feels good to help someone in a fix. Lord knows I've been there several times myself.
Thank you for calling me 'friend', I like that.
I have an Armstrong SX 90 Ultra using LP gas. I know Lp gas produces a lot of condensate as it burns. My problem is the condensate has collected in the inducer fan
My question is why does condensate collect in the inducer fan and the PVC pipe connected to it. Isn't this pipe under a vacuum?.