Most likely, either the electrical system providing your furnace’s power has shorted or the power switch has blown. Try resetting your furnace’s circuit breaker. If it has blown, you will need to replace it. The furnace’s igniter might either be cracked or faulty. Check the part for cracks, if it is then replace the igniter. Armstrong Error code (9 flashes) I went to switch my furnace to heat for the first time after summer, only to find it sadly dead... It is relatively new (installed only 10 months ago!), Armstrong (G1N80BU) and is blowing the 5A blade fuse on the circuit board. I can't hear anything happen prior to the fuse blowing (like the igniter, etc).