the johnson control is pure junk, I just bought a new one and does not work at all, put back the old one that works intermitently--it is the third one in two years! time to put a different furnace. I returned to the manufacturer the control uniit in milwaukee with no success.
possibly honeywell makes one as well. same exact problems, took the entire furnace apart, clean it and still problems, no ignition, or no flamme, so frustrating!