The air filters on these units consist of a nylon mesh, simply a screen material.
The frequency with which you will clean the filter on a Velit rooftop AC unit will vary based on a number of factors. This includes the climate/environment, hours run, and if any pets live in the space, as a few examples.
The filter lives inside the U shapped perferated panel on the air distribution box. It has 3 tabs that can be easily released with a flat-head screwdriver. As a general quick maintenance, you can always wipe the outside of the filter without removing it to clean any surface dust.
Once removed, you should gently clean the filter with warm soapy water and air dry completely. You can then replace the filter back into the air distribution box.
If the screen comes detached from the casing, it's ok, you can use a little superglue to tack it back in place. But once the screen is reinstalled, the outer casing holds it in place sufficiently.
A clean filter is going to prevent issues and increase performance.
If you need a replacement, we sell them here: https://velitcamping.com/collections/air-conditioner-parts/products/rooftop-inside-intake-inside-vent-screen
