Hello, I have a Tempstar gas furnace model# NDN6050FBA1, It runs for 1-2 minutes then shuts off. I can hear the fan turn on, gas ignite, and then the blower motor. It doesn't run long enough to heat up and of coarse we are experiencing freezing temps. I wonder if my thermostat is going bad? Any suggestions would be greatly appreciated.

Thanks, Kevin

Forgot to mention everything is clean, had the furnace serviced last spring.

If you can see the burner area, how long is flame present before shutting down?

Its present for about 1 min or more but no more than 2 min.

I started messing with the thermostat to figure out which wire do what. Now the furnace is putting out some heat. Maybe my thermostat ( electronic Honeywell) is starting to go.

Try this: turn off power to furnace, disconnect "R" and "W" wires from thermostat, and connect them together. Now power up furnace and see how it runs.

Thanks kc13, After my last post the furnace started to work and heated the house. If it happens again I will try this.
Thanks again, Kevin

Forgot to mention everything is clean, had the furnace serviced last spring.
I'm going to almost bet that your flame sensor is dirty and causing an intermittent problem. Just because it was cleaned last spring doesn't mean that they cleaned the FS. A spring inspection/cleaning is usually more targeted at A/C operation. I usually recommend a clean and check 2 times a year. Once in late spring for A/C season and then again in early fall for heat season.

Thanks Mark, as of know everything is working like it should and I'll take your advice and clean the flame sensor.