Every 2 weeks or so, my furnace will not kick on. The heating and air guy has replaced 2 thermostats, control circuit board, cleaned the flame sensor & limits, checked flue pipe and checked for flame rollout. I usually just have to go to the thermostat and make it go down under the temperature and put it back up for it to kick on. Yesterday it would kick on but it wouldn't kick on to the heating cycle. It would kick back off. So I just left it off all night. What could it be?
I don't see you mention a pressure switch... it kind of sounds like it could be on its way out. These are one of the few parts that can slowly die whereas others usually either work or don't.
Updated on February 20, 2018
By Dan Robbins