Hello, My furnace recently went out (on the coldest day in Chicago nonetheless). It turns out that the intermittent pilot control (Johnson Controls G779) failed from being overheated. We could see warping around the circuit board, but it also turned out that the air filter was also plugged.
After installing a new pilot control and air filter, I am very worried that the heater may still be overheating. The heater has been on for several hours to heat the house up from a warm 37 degrees. The burners go on for 4-5 mintutes, and then shut off. After 1-2 mintutes they are reignited. The fan stays on for the whole time. This process repeats itself while the thermostat is still set.
Is this normal for an old gas furnace that has been on for a while? The technician said that if it displayed behavior like this the A-coil may be plugged. Is this likely? Any tips would be most appreciated. Thank you.
-Charles