I have a 7-8 year old york 80 upflow model that will not turn on when the heat is turned on. The blower works when the fan turned on the thermostat and the a/c works. Last night, the heat did work before I went to bed. The humidifier was turned on and when I woke up in the middle of the night freezing, I realized the heater was no longer working. The humidifier which is located above the burner compartment had leaked water onto the gas valve and the wiring. I checked the small fuse in the blower compartment and it was fine.
The led light was blinking twice.