You flip on your AC, settle in for the evening, and then — something stops you cold. There's a smell coming from the vents. Something burning. Something wrong. Your first instinct might be to tell yourself it's nothing. Maybe it's just dust. Maybe it'll go away. And sometimes, yes, it does go away on its own. But sometimes it doesn't — and ignoring a burning smell from your air conditioner is one of those home maintenance mistakes that can go from a minor inconvenience to a s