The foil duct is connected to a Black ABS type tube. Inside that tube is the 12 volt fan. It is usually mounted on the sidewall of the drivers side storage almost to the roof of the storage. There IS a fuse for that separate fan. The fuse is located on top/side of the Furnace case. Accessed by removing the inside louvered Wood access door in front of the furnace in the hallway. There will be 2 ATC fuse holders. One is for that fan. Can't remember what the other is for, but I believe it is a separate fuse going to the furnace Tstat output going to the AC control board. Some older models you have to remove the OUTSIDE furnace door to get easier access to those 2 fuse holders. Newmar changed the access to the inside to make it easier after complaints. Doug