Lots of interesting advice! In answer to one question, we don't use our a/c very often -- maybe ten nights per year. (Mostly we boondock.) But we tow off road a lot, which kicks up a lot of dust. So I am guessing that things are pretty dirty up there.
It sounds like most of our commentators are DIYers. I usually am, too, but I have learned over the years to be careful -- to paraphrase Don Rumsfeld, "you don't know what you don't know." (Remember the "unknown unknowns?") To paraphrase another maxim, I don't want my head to write checks that my hands can't cash. ;)
If I were to go onto the roof and remove the plastic housing and spray stuff onto the fins or whatever, what would keep the gunk from dripping down into the trailer itself??
