Cayenne windscreen de-mist problem (air not ducted to screen)

[hamisha]

I have a UK dealer supplied 2005 Cayenne 3.2 v6 with Tiptronic and automatic 2-zone air conditioning. Over the last couple of days (coincidentally since the car came back from a main dealer service, during which a service campaign 'upgrade' was carried out) the front windscreen de-mist function has stopped working.

When the button is pressed, the fan speed increases and air is cut from the ventilation outlets, but no air comes out from the duct at the base of the windscreen. It's as if a duct or vent isn't opening to allow air to the screen. I've checked all the fuses, but all are in order.

Any idea what could be causing this, and whether it's something that is easily fixed? Or is it another trip back to the dealer?

Many thanks!

[RFM]

The servo motor most nearly the firewall on the left upper side of the unit ( passenger side in your case ) controls the windscreen function, look for working. If not, a visit to the dealer is recommended.

[hamisha]

The servo motor most nearly the firewall on the left upper side of the unit ( passenger side in your case ) controls the windscreen function, look for working. If not, a visit to the dealer is recommended.

Many thanks for your reponse RFM. How would I check whether the servo motor is working? Can I assume it isn't if the fan is blowing but no air is exiting the windscreen ventilation duct?

[RFM]

Grab the motor with your hand, you can feel the motor working if you go to an other combination and back.