Of all wonderful things, I am working on m furnace tonight. The ignitor module is acting up. This unit has the" internal" sensor by using the spark wire and checking for uA on the ground strap. I verified that the current is there but for some reason, pilot will start, flame is good, will start to light the main burner, then just shut down and repeat this endlessly.
I finally just jumpered over to 24V for the main gas valve so I can get some heat in the house but I will get no sleep babysitting that.
I pulled the PCB for the ignitor and all testing fine except some unknown component. All I could find on it was "68A" and PCB is marked as "VR" with no polarity. Device is a typical black axial lead component probably 4x8mm or so. The component tested open with continuity and diode tests. I decided to just break it open to try and understand what it was and looks like a thin wafer between axial leads. Like a black/green disc about 1mm thick.
I am going to have to guess what the heck this was and try something. I put the PCB back in so I can by pass it and get heat and still running like before without that component. Not sure if that was really the issue or not. I was about to just put a 10K resistor in there but something tells me I should check with sharper electronic minds before possibly toasting it. Just cannot tell what it was supposed to do... It seems to have had connection between primary and secondary coils for the boost coil for the spark. There is, however, another high voltage boost coil as well.