I have a Trane XR80 furnace. The furnace works fine sometimes, and other times is will not light. I get no error on the LED indicator on the main board. The ignitor gets hot but the furnace will not light. It appears that there is no gas getting to the burners. Any suggestions would be greatly appreciated. Where could I find a schematic of the furnace wiring?

Look on the back side of the blower access door for the schematic since they all leave the factory with one.

An intermittent problem is the worst kind to have. You might clean the flame sensor with some fine sand paper or steel wool since this is a no cost item. If that does not help then you will have to sit at the furnace with an electric meter attached to the gas valve and wait for the failure to se if it is the gas valve or the 24 volt signal supply that is missing going to the gas valve. As you can see this is not an option for most people and since your circuit board is not indicating trouble you just might have to wait for a failure or be foolish like some people and start replacing parts that you do not know are defective.

The furnace was working fine for a while again, but yesterday it acted up again. I cleaned the flame sensor and it seems to be working for now. I cleaned it before and it worked for a while, then started acting up again. I guess time will tell. It seems to be fine now. Thanks for the info.

See this thread also


https://www.askmehelpdesk.com/heatin...em-448053.html

This is great info. Thanks hvac100. I'll keep my fingers crossed and hope it keeps running properly. Thanks again for your help.