No heat just cold air

[onlyawoodworker]

I have a Trane XB80 furnace w/o AC. It's flashing an error code and according to the service manual its the "open temp limit circuit". When the furnace is turned on, occasionally the burner would light, but soon will go out and just blow cold air. I have replaced the filters, cleaned out the exhaust vent, replaced some damaged vent pipe in the crawl space and inspected all the runs for any blockage. All heat registers all have good flow. Iv'e bypassed the limit switch to check if it needed replacement but the LED still flashes the same error code and the heat goes off. I've also checked the limit switch with a test meter and the circuit is closed. Iv'e reset the system many times and the igniter glows but will not light the burners at all anymore. It just cycles cold air and the fan runs continuously. Any chance the problem could be a bad circuit board or is there something else I'm over looking?

[rider77]

Im sorry, but this site does not allow DIY advice or help. It was in the rules you agreed to when you signed up.
Id recommend having a professional properly diagnose it so no money is wasted throwing parts at it.
Many people are quick to blame boards. They are rarely the actual issue.

[dougfamous]

IIv'e bypassed the limit switch to check if it needed replacement but the LED still flashes the same error code and the heat goes off. I've also checked the limit switch with a test meter and the circuit is closed.

Please stop now before you injure yourself or make your problem much, much worse. Jumping safeties is NOT something you should be doing. If you've checked the filter and it's clean then please call someone and get it serviced.

[Dad]

I have a Trane XB80 furnace w/o AC. It's flashing an error code and according to the service manual its the "open temp limit circuit". When the furnace is turned on, occasionally the burner would light, but soon will go out and just blow cold air. I have replaced the filters, cleaned out the exhaust vent, replaced some damaged vent pipe in the crawl space and inspected all the runs for any blockage. All heat registers all have good flow. Iv'e bypassed the limit switch to check if it needed replacement but the LED still flashes the same error code and the heat goes off. I've also checked the limit switch with a test meter and the circuit is closed. Iv'e reset the system many times and the igniter glows but will not light the burners at all anymore. It just cycles cold air and the fan runs continuously. Any chance the problem could be a bad circuit board or is there something else I'm over looking?

To the OP..

We have no idea of your background in such things or how "handy" you may be or the others who may read your request for assistance... thus we can't give you that kind of advice on the site. Sorry.

As mentioned, it is unsafe, unless you are in our business, to test by jumping out any safety on your furnace.

We feel for you and know it is cold but we would all rather you be cold and safe instead of any in other predicament.

This thread is closed