Question on new 2015 Ranger 900 Crew with Fortress Brand windshield and Fortress roof

I just got my 2015 Ranger 900 Crew and I bought the Fortress brand steel roof and the Fortress brand split slide windshield. I did not get an Audio System however there are slots for the Audio unit and the slots on both sides of the Audio unit for speakers. Since I did not get an Audio system, there is a lot of cold air that comes through those empty Audio slots and it seems there should be a cover plate for that area to block the air. Did my dealer leave something off or are the empty slots just supposed to be left open when there is no Audion unit installed. Thanks very much.
Mark