Hello I have a intertherm furnace and we tried to fire it up today and the red light is on all the time and the yellow light is not lighted up at all. m1m model furnace say on the wireing diagram say. 1/ yellow light shoud be on, furnace starts up you can hear gas vavle kick on, and if you open the little door you can smell the gas. Please help

Here is your service manual

http://www.nordyne.com/Literature/690a.pdf

Your unit starts on page 28. All the trouble codes are there etc. Yellow lite off means no flame signal is being sent to board.

If this unit is on LP gas be very careful when trying to repair.

There are many possibilitys for problems but you might start by checking the ignitor with a meter and the voltage source for same.