Looking for advice on the problem with my furnace.
I have an 11yr old Comfortmaker RPJ II furnace and am having intermittent heat problems. The furnace is unable to reach the desired temp without repeated manual calls for heat. On the first cycle, it runs properly, on a 2nd cycle the ignitor glows but the gas valve will not open so I only get room temp air blowing. On the 3rd cycle attempt the ignitor will not glow and valve will not open.
Wondering if anyone knows if this is a sensor issue or a control board issue?