scenic screen demisting problem

[dodgyphil]

Hi guys!
wonder if someone can help me out.recently bought a 1999/2000 scenic 2.0 16v monaco,been trying to work out the best way to clear the screen.followed the renault handbook method,a/c on air on recirculate, vents to screen only,heat right up.eventually it will clear!!BUT there doesnt seem to be much air being blown out the screen vents,or heat!when it does clear if I leave it parked for an hour or so the screen will be very wet,and we're back to where we started again!! I've never met a car that was such a pain in the butt to clear the screen of,however I remember the early lagunas had problems with the heater matrixs leaking,I can't find any wet in the carpets etc. but could this be part of the problem?do I have a pollen filter fitted,if so where is it?also as another little thing,no matter whether I select the front or rear screen washers only the front ever work,anyone got an idea why?
be grateful for all advice
cheers people,
Phil