VW Passat 2000 air inlet sucks outside air only

Im baffeld and so is my hubby. Basically when we turn on the air conditioning in the car its impossible to get any setting that allows us only to recycle air in side the car when sitting in traffic and you dont want outside air to enter. Any ideas of what to check. Its been at a mechanic but we are in Cairo Egypt and some are not so reliable so we are out of ideas and fed up of smelly air and not being able to utilise the ac. We were told by somebody there is a technique to use to make a flap move by pumping up the air speed and then hitting another button. sounds wierd to me. Please help the non teccy lady sort out her problem. Thank you so much…