Camco 40408 RV A/C Air Filter, Ducted Ceiling 4-Pack

If your RV's rooftop air conditioner isn't cooling like it used to, the filter is the first thing to check. This four-pack of Camco RV A/C air filter replacements drops into ducted ceiling return-air assemblies and gets airflow back where it belongs. Clean air in, cold air out. It's a small part, but a clogged or missing filter makes the whole unit work a lot harder than it should.

These are built for RV air conditioners that use a Dometic ducted ceiling assembly, the kind with a return-air grille that measures 14-1/8 inches by 7-11/16 inches. Each filter itself measures 13-7/8 inches long by 7-13/32 inches wide by 1/4 inch thick, so it seats cleanly inside that grille without bunching or leaving gaps at the edges. If you've got a ducted system running through the ceiling of your coach, this is almost certainly the return-air filter shape you're looking at. Pull your existing one and measure it against those numbers before you order.

The filter is cut from polyester-based polyurethane foam. That open-cell foam catches dust, pollen, and the fine road grit that works its way into a coach over a season of travel, while still letting the blower pull plenty of air through. And because it's foam and not paper, you don't throw it away every time it gets dirty. Rinse it out by hand, let it dry, and slide it back in. We clean ours a couple of times over a busy summer and only swap in a fresh one when the foam finally starts to break down.

That's where the four-pack earns its keep. One filter goes in now, and you've got three more on the shelf for the rest of the season, or spread across a couple of A/C units if your rig runs more than one. Full-timers and folks who camp in dusty country go through them faster, so having spares in the storage bay beats hunting one down at a campground store in the middle of July.

Install is about as easy as RV maintenance gets. Pop off the interior return-air grille, usually held by a couple of tabs or thumbscrews, lift out the old filter, and set the new one in its place. No tools, no wiring, nothing to calibrate. The black foam sits behind the grille and stays out of sight, so it won't stand out against a white ceiling assembly. Snap the grille back on and you're done in under a minute.

Why bother keeping up with it? A dirty filter chokes the return air, and that's rough on the air conditioner. The blower strains, the coil can ice up in humid weather, and you lose cooling right when you need it most. Worse, all that dust ends up on the evaporator coil instead of in the filter, and cleaning a coil is a much bigger job than rinsing a piece of foam. A fresh filter is cheap insurance for an expensive rooftop unit.

Keep in mind this is the return-air filter for a ducted ceiling assembly, not a part for non-ducted units that blow straight down through the shroud. If you're not sure which style you have, look up at the ceiling. Ducted systems feed air through vents spread down the length of the coach, while non-ducted units push air right out of the A/C housing itself. When in doubt, measure your grille and match it to the 14-1/8 by 7-11/16 inch opening these are made for.

It's a simple part, but it's one of those little maintenance items that keeps a good air conditioner running like new. Grab the four-pack, keep the spares handy, and give your rooftop unit the airflow it was designed to move.