What your wife did should NOT have shut the furnace down. I think it was a coincidence. Intake or interior exhaust vent blockage will not shut a furnace down. It might kick out the over temp switch, but that switch will auto reset unless defective. IF it does trip and not reset, the furnace will still come on and attempt to fire 3 times before shutting down. If your furnace fan does not come on at all, then either the furnace fuse is blown OR on some models, they do have a 12 volt circuit breaker inside the furnace that must be manually reset. So, check all you coach 12 volt fuses at the fuse panel. IF you have the model furnace that has an outside access door, remove it and you will see a schematic and also that circuit breaker if you have one. Doug