The problem is a very musty odor, especially in two closets, where mildew has been seen on shoes. It would seem the obvious cause would be dampness from somewhere. But where?
This is a 60 year old house, which my daughter bought 6 years ago Don't know what the original exterior was, but now has siding which is several years old. There is an attic. No apparent leaks in the roof. Working sump pump in the crawl space. Replacement windows were installed last year.. Gas heat, AC which she seldom uses because she prefers fresh air and keeps windows open.
No exhaust fans in bathroom or kitchen.
Any ideas as to how to determine the cause of the odor?