# Lennox Furnace - Primary or Secondary Limit Switch Open



## georgemeaders (Sep 11, 2012)

My furnace stopped working today. It will turn on for a few seconds and then back off again, occasionally turning on for closer to a minute. The lights indicate that a limit switch is open. I've read enough where I think I can figure out if the limit switch is the problem by taking out the wires and bypassing the switch to see if it works and then just get a new limit switch. I don't know what the limit switches are, however. Can anyone tell if this is a good idea, and where in the attached pictures the limit switches are that I should be testing?


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## yuri (Nov 29, 2008)

Where is the picture. Go to (Go Advanced- manage attachments) to upload one. What is the complete model # of the furnace and serial #. Several Lennox techs here.


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## georgemeaders (Sep 11, 2012)

Sorry about that, one image is attached now. I will have to wait until I get back from work to check on the actual model # of the furnace in question, unless one of the pictures I took this morning has the model # included.


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## yuri (Nov 29, 2008)

Looks like a counterflow/down flow G24 which is a VERY nasty furnace to work on. Limit controls are in the fan compartment and you need to remove the venting etc. I would HIGHLY advise you to call an experienced Lennox tech to deal with that problem. Not something I can walk you thru over the internet w/o other problems occuring. Sorry.:huh:


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## georgemeaders (Sep 11, 2012)

Yikes, that sounds nasty. I added another picture of where I think you're referring to. I might go ahead and call the guy who comes out to service it every couple years and see if he can take a look at it. I was hoping to be able to save a few bucks on it, but don't want to risk screwing things up too badly.


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