The Fresh/Recirc Flap basically directs air that is to be sucked in to the fan, from either the Cabin (Behind the Dash), or the Vents located in front of the windscreen, on the outside of the car (Where the wipers bolt in).
If that flap is broken, then you will be stuck with either fresh air all the time, or Recirculated (Cabin) Air all the time, regardless of the switch setting.
What are the symptoms/problems that you are having ?
Is it that all the flaps seem to be doing whatever they want, or certain Air Outlets cannot be selected ???
From Memory, there are something like 4 Vacume Controlled Flaps on the airbox, so If only one of the Airflow outlets isnt working, then I would guess that maybe the Flap has broken, or that there is a leak with that particular hose that feeds the Flap.
If all of them are stuffed, then its likely that either you arent getting any vacume from the motor, or the Vacume Control solenoid is stuffed, or the Controller is Stuffed. (Also the Elelctrical Cabling going to these could be stuffed, loose, unplugged as well !)