I have noticed since I bought my car that the rear vents seem to have little or no air coming out of them under all conditions. So I searched and only found 2 explanations, either the ducting is disconected or the "air flap" motor isnt working. How would I check to see if it is working? where is it?

Hopefully Ill find a reasonably priced manual soon and can stop bugging you guys. Thanks in advance.