Odds are they have never been replaced. usually on a CC, you have a wooden/plastic decorative ceiling assbly with recessed lights in the center of the ceiling(front and bedroom). There are either hooks or bolts holding that assbly to the roof. It is then hinged usually on the pass side. You use a step ladder and find those bolts/latches. you remove them and the ceiling assbly tilts down. Once down, you will see the AC filters. They are usually 14 inch square filters. They will NOT be serviceable from the top side of the RV. Doug
