Ed:
I just took out one of those vents after my daughter knocked the plastic
flaps loose--don't remember if it was held in by 2 little screws, or if the
unit just "pops" out, but it was no hassle.  Then you can adjust the foam
inside--it does have a purpose, as you will see that part of the compartment
is not part of the ventilation system, and is therefore blocked off by the
foam--the fresh air comes from the "outside" channel, and out the little
plastic vents.
Jim