Does anyone have any suggestions on cleaning the a/c ducts that run along the ceiling in most rv? My 5th wheel is about 20 years old, I've had it about 5 years, and the ducts smell like they need a good clean out when the a/c hasn't been run for a few hours. I'm thinking, remove the vents and use flexible rod with rag attached to the end and sweep out as much dust as possible followed by a quick spray with some very diluted bleach. Any thoughts/idea.