furnace doesn't always blow hot air


Old 10-26-06, 03:42 AM
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Join Date: Oct 2006
Posts: 2
Question furnace doesn't always blow hot air

Hi, I have an American Standard Freedom 80 natural gas furnace in my home. Before I explain my problem I should preface this with saying that I don't understand too much about these systems. I know that when the furnace is switched on, an electric filament is heated, and after about 10 or 15 seconds a click can be heard followed by the flow of gas. The gas ignites, the filament cools, and a few seconds later fans begin blowing the warm air. Here is my problem:

Sometimes (not every time), the gas simply doesn't ignite. The filament will heat every time, but on occasion the click will be heard, but no ignition occurs. When this happens the fans will still start up, and they will simply blow cold air instead of heated air. When this has happened, stopping and restarting the furnace several times will usually get it going. Also, it appears that once the furnace is working properly, it will start correctly each time until we turn the heat down and the unit gets "cold" again. So, we generally only have to deal with this problem in the morning.

If anyone could give me their guidance I’d really appreciate it.

Thank you.
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Old 10-26-06, 01:21 PM
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Location: Rochester, Minnesota
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When was the last time you had cleaning done to it?

Either the burners needs to be cleaned or the ignitor is getting worn out and may needs to be replaced.
Old 10-27-06, 04:02 AM
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Join Date: Oct 2006
Posts: 2

Thank you for the feedback Jay. The furnace was actually cleaned 3 weeks ago. I had a HVAC technician come by 3 weeks ago to look at a different problem; we were worried about a grinding noise that seemed to be coming from the furnace periodically. The technician identified the noise as being related to a faulty "inductor draft motor". The technician explained that if the draft motor were to stop operating that the furnace would not turn on. I bring this point up because I believe the draft motor is working fine; that is it spins constantly, and since the technician played with it, it stopped making the noise.

Anyway, since the technician was here and he had fixed my other problem in about 5 minutes and I had to pay him for an hour, I asked him to clean the unit. According to my receipt, he states that he "cleaned out blower and burner section". Do you think that is representative of a proper cleaning?

You state that it is likely that the system needs to be cleaned or that the igniter is worn. Is the igniter the filament that lights up just before ignition or something else?

Are the jets on a gas furnace similar to those on say a stove? I'm wondering if it wouldn't hurt to take a bristle from a broom and clean the holes on the jet, or is such a task unadvisable?

Let me know what you think, and thanks so much for your assistance with this.
Old 10-27-06, 05:20 AM
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Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 18,427
The ignitor (filament in your word) can ware out over time, even thou it glowing bright orange, it just don't have the heat to ignite the gas. Ignitor can not be cleaned, so don't touch it or try to clean it.

Cleaning of the burners can use the brush, and shop-vac or air hose.
Old 11-03-06, 09:46 AM
Join Date: Nov 2006
Location: Edmonton, Alberta, Canada
Posts: 3
Furnace not lighting

I have the exact same furnace. About 3 years ago I bought a rental property with this American Standard Freedom 80 furnance in it. Until this winter I never had to touch it. I am having some problems with the fan blowing beyond its times limit. As part of the maintenance I did on this furnance I changed the heat sensor and ignitor. By the look of the graveyard of ignitors laying in the bottom of the furnace I suspect these need to be changed at some frequency. I think this $35.00 replacement will solve you problems. You may want to do the heat sensor as well. Expecially if they are 5 or 6 years old.
Hope this helps.
I think I paid $100 total for parts and it is an easy fix. Do it your self. Also, do not! touch the heat sensor or it is toast.
Old 12-20-12, 06:32 AM
Join Date: Dec 2012
Location: USA
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I see it's been 6 years ago but do you remember if you were able to fix the problem?
Old 12-20-12, 06:55 AM
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He hasn't been logged into the board since December 06.
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