Woke up this morning to the smell of something getting hot.
About time my eyes opened the smoke detector goes off. The capacitor on the furnace fan motor had went out. When the heat kicked on it went into its high fire heat up stage at which the fan will come on a minute later. No working capacitor, no working fan. The furnace ran with no airflow until the tripped out on high heat. Good thing for built in fail safes. Otherwise it might have been bad for me. Capacitor replaced and furnace working as it should and since I was already in there it good a good cleaning too