Air conditioner filters in the RV are often overlooked for replacement because, after all, the RV only gets pulled out when you are ready to use it. Unlike the home air filters that are routinely changed every several months on a regular schedule.
The air conditioner filters in the RV do need to be replaced periodically. Next time you are in the RV, take a quick look up at the ceiling air intake to see if it is time for replacement. The replacement material is inexpensive and can usually be found at your local home improvement store.
While checking the filters, look at the ducts to see if they should be cleaned. Also, check the operation of the metal or plastic vents to make sure they have not frozen in place. If there is any rust present, pull them down, sand them and repaint them to get them fully reconditioned.