Filter for Atwood furnace

Wow, Thanks for all of the responses. Read a few remarks on other forums where some individuals had installed mesh filters to stop dust and dirt from entering their furnace compartment. Idea was to prolong furnace life and prevent the smell you often get when starting up in the fall. None of my Atwood literature said anything pro or con about filters, and yes I probably should have called before asking a dumb question. Meanwhile, I shan't be a trial and error statistic and will think outside the box on others things.