Update: Well, I took Rick’s advice, picked up some good quality foil tape at Lowe’s this morning, and set to work on the duct openings. Cut the tape in several strips about 1/2” wide, and used them to tape all around the vent openings so none of the 1” styrofoam insulation is exposed. Ended up doing this to every duct where we’d seen white dust coming from, a total of 5 of them.
Cranked up air conditioner, and….no more white dust. Problem solved. That foil tape is good stuff, seems to hold and stick really well. Will definitely keep it in the motorhome in case we need it again.
Thought about doing all the duct openings/vents, and may well on the future. All is good for now, though, so gonna move on to more fun stuff, like getting back out camping. :)
