What do I have in my return air duct?
I live near a dry canyon (active wildlife area) and I have a bad smell that seems to be coming from a return air duct vent in my bedroom ceiling. Have had numerous "experts" to attempt to discover what it is. The smell comes and goes....isn't every day or every night. Happens in summer and winter. Usually when I bang on the vent the smell starts going away. Have had people in the attic and in the crawl space, have had our vents vacuumed out. Help???? 541-420-4556 email@example.com. Thank you!
You have done a through job of evaluating on your own. It does not sound like a wildlife issue but more of an environmental issue. Odors are related to every thing in the environment, particles of one type react with particulates of another and you get something completely different from either. We suggest you continue ruling out items until the source is evident. From your description you should be ruling out the ventilation system.