furnace wont work

[Titleguy]

Had a similar problem with mine, would work when connected to shore power, but not with battery power. I knew my batteries where marginal so I purchased 2 brand new group 29's. Still had the same problem. I determined it had to be a voltage problem to the blower motor, not generating enough air flow to get the sail switch to work. Cleaned the ground connection to the frame and works beautifully now.

[Herk7769]

Yep, anything that will slow the fan down will cause this problem. Not enough air flow will prevent the sail switch from closing and firing the burner.

[SLCaton]

cthelite: We had the same problem with our furnace... blower would blow for 30 seconds or so but no audible igniting 'click' and then the blower would shut off. Our repair dude replaced our circuit board and it worked fine. If the other suggestions offered here don't seem to work, you might want to look into the circuit board...