I apologize.. I am not sure what the "correct" term for the button/switch is. It is a small black button that is located right above the control panel.

My Mom has a Coleman furnace in her Mobile home and it won't stay running. We have checked the intake and exhaust..turned the thermostat off and back on.. and have had several furnace repair men out to check it and they can't figure out the problem. It runs off of LP and we also cleaned all the snow...