# Lennox Pulse Furnace comes on intermittently



## mr_cip (Dec 11, 2009)

My furnace is set on manual at 62F. One day the house was down to 55F and the gas furnace never came on. I hit the off/on toggle switch next to the furnace in the basement off, then immediately on and the furnace started running. It worked flawlessly for a few days that it happened again. I thought it might be an old battery in the thermostat (it is a newer programmable one ...but set to manual), so I replaced that. Again it worked great for 3 or 4 days, but now it failed to come on once again (so I repeated the off-on switch and it is running currently). If it is a sensor in the furnace, why does cycling the furnace off then on correct the problem temporarily?

Thanks for any help in this!!!


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## JohnWill (Oct 19, 2002)

It could be a control board that is going "into the weeds" and needs a power cycle to reset it.


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## Who's Me (Aug 29, 2006)

Depending on the model there may be a little inspection window that you can look through.
should be two LEDs they will flash trouble codes if so check the manual for codes.
Could also very well just be a clogged air filter Which will shut down the unit and force you to restart manually.


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## Mumbodog (Oct 3, 2007)

Gas?

see this, looks like a great support forum for Lennox
http://www.cozyparts.com/lennox-parts/forum/topic.asp?TOPIC_ID=1025

.


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## Koot (Nov 25, 2007)

It might just be a defective service switch (single pole light swith) that you've turned Off and then back On again in order to get the furnace to operate for a few days. Replacing the switch would be a simple and minimal cost first step in troubleshooting.


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## Frank4d (Sep 10, 2006)

It could be a bad igniter. If the igniter fails to get hot enough to ignite the gas burner, the furnace controller will go into lockout mode. Cycling power to the furnace resets it.

I had a problem similar to yours a couple of years ago. The igniter sometimes would glow bright white (like it should), and sometimes it would glow sort of dull orange. A new igniter (about $50) fixed it.

Edit: If you look closely at a bad igniter sometimes you can see where it is cracked.


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## John1962 (Jan 11, 2010)

Try cleaning the condensate drain trap where the furnace drains


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## wacor (Feb 22, 2005)

one post drive by a month old it appears


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