My windscreen demister does not work, I can hear the heaters working but nothing comes out them

EASY FIX HAD SAME PROBLEM WITH MY AUDI A4 2002 JUST LAST WEEK.....WILL BE ONE OF THE CONTROL MOTORS FOR AIR FLOW...UNSCREW THE 4 OR 5 SCREWS THAT HOLD THE GLOVEBOX IN PLACE TAKE CARE TO UNPLUG GLOVEBOX LIGHT WHEN LIFTING OUT...NOW YOU WILL SEE ALL THE CONTROL MOTORS RIGHT-HAND SIDE OF YOU...EACH ONE CHANGES THE AIR FLOW ...THE ONE FOR THE WINDSCREEN IS THE ONE NEAREST TO THE FRONT OF THE CAR..UNPLUG THE WIRING CONNECTOR UNDO THE 2 SCREWS NOTING HOW THE MOTOR SHAFT ENGAGES...EASY....IF YOUR UNSURE WHICH CONTROL MOTOR IT IS TURN ON YOUR BLOWERS AND TEST EACH ONE..SIDE VENTS, DEMISTER,ETC...TRY AND GET A SECONDHAND CONTROL MOTOR FROM SCRAP YARD...DEALERSHIP PRICES JUST A JOKE.. FOR A CHEAP TINY MOTOR NOT MUCH BIGGER THAN A MATCH BOX OVER A £100 SCRAP YARD £5 POUNDS...........HOPE THIS WILL BE OF SOME HELP TO YOU...

I've had the same problem with my 52 plate A4 1.9tdi. Had the problem since I bought it. No air from the demister and when I turn the ignition off it sounds like a vent valve is opening and closing continusley, this continues for about five mins then stops. Did what other members did, removed the glove box and tested all the valve opening motors by putting on the front, bottom them windscreen demisters. The motor connected to the green linkage arm (demister) didn't move at all while the other two did. Took the motor off, opened it up via 3 or 4 plastic clips and doused it in electrical contact cleaner and the moving plastic parts in silicone spray. 'Tapped' the silver motor a few times with a screwdriver, waited for it to dry and re-assembled. The demister sprang into life when I reconnected to the green plastic arm. I also sprayed all 3 linkages with silicon spray and I can hardly hear any of the movement any more and the valve opening/closing noise when I turn the engine off is gone too. All in all it took about two hours