While it may not seem such a critical item in winter, keeping your roof vents clean and fully operational is an RVers “good thing.” In winter, particularly in damp climates, keeping the roof vent cracked just a tad will help ventilate moisture from cooking and breathing. The results are a better living environment and less weeping on the walls.
Roof vent covers and screens are prone to dust collection, and those in the bathroom often pile up mold or mildew–harmful to folks with lung ailments. Cleaning them is usually a pretty simple matter of removing the crank and a couple of screws holding the screen in place. Clean the lids with a non-abrasive household cleaner and a soft cloth. Screens can be scrubbed up in the sink with a soft bristle brush, warm water, and dish soap. A toothbrush may be just the ticket, but skip the “Gleem.” That toothbrush might be called on for hitting skinny corners and tracks around the vent lid itself, too.
While you’re at it, take a good look at the gasket around the roof vent. If it’s come loose, first try to reseat it; if it pops back up you may need to tack it back in place with a good glue, appropriate for use with rubber.