Troubleshooting Gas Furnace Problems
Turns out to be a bad gas control valve. Its sporadic behavior was a sign that it's failing. After testing the thermostat, igniter, and flame sensor, the only odd behavior was the occasional loss of flame triggering ignition lockout. As for the blown fuse, it's possibly a bad solenoid or related component on the valve drawing too much current. Gas doesn't seem to be flowing after hearing the &quot;click&quot; since the last failure. Replacing the valve returned the furnace to working order.