I live in a warm, humid, coastal town and when my air conditioning runs it creates condensation in some areas. This week I noticed rust on the wallpaper under one of my sconces and when I open it up, the mounting screws were badly rusted and the interior of the sconce was very wet. The junction box in the wall smells damp and mildewy.
It's possible that the water is coming from somewhere else, but the junction box itself seems dry. E.g. there's dry drywall dust inside it.
How should I address this?