If you aren’t certain that the air filters in your cooling system are of this type, you shouldn’t assume that they can be cleaned and reused at maintenance time.
Unless your filters are made to be reused, you should remove them from the cabinet, discard them, and replace them with brand-new ones.
Your air conditioning filters catch a great many types of contaminants and other debris from one maintenance visit to the next, and these particles are often trapped well below the surface, in the filter fibers. Dust, pollen, and dirt particles at the inner portion of the filter will never be removed by surface cleaning or vacuuming. In reality, these pollutants will create a kind of barrier that prevents air from passing through the filter, making your air conditioner less efficient, or even damaging it. Since air filters aren’t designed to shed moisture, your cleaning efforts may leave them wet. As moisture is retained over time, it can easily promote the growth of mold and mildew, which would then spread throughout your house where the duct work carries it. Even if mold and mildew do not develop, a wet filter is much less effective at trapping pollutants than a dry filter. Cleansing efforts may be well-intentioned, but they can easily damage the filter’s construction. Slapping the filter against a hard surface to remove dirt and debris can cause damage on its own. It can also compromise the somewhat delicate construction of the fibers if you attempt to pick something out of the filter, and if you tear a hole in the fibers, the filter will not be as efficient or effective as it was originally. Even though it’s safe to clean and reinstall filters designed for reusability, it’s important to remember that for them to be really effective, they should be cleaned often, even up to once a month. The particles they remove from the indoor air slowly begin to clog the filter when they’re not cleaned often, so the longer it’s between cleanings, the less efficient the air conditioner will be.