What a failing furnace sounds and smells like
A furnace that used to kick on quiet and now bangs, rattles or squeals is telling you a part has worn loose or is about to fail. Short cycling, where it fires up and shuts off again before the house warms, usually points to a clogged filter, a cracked heat exchanger or a flame sensor that's lost its read. A burning smell on startup can be normal dust burning off, but one that lingers or smells like metal means a tech needs to look at it before you run it again.









