windscreen not demisting

[weeleigh]

The front screen will not demist on my 03 A4 Avant 1.9 Tdi SE. No matter what setting I use, manual, auto, or use the demist button, I can't get air to come out of the screen vents. I get heat from the side and face vents, and also to my feet.
I noticed through the summer my aircon didn't seem to be working, and I also get clicks and whirrs from the fascia.
Last year I get a friend from the forum to do a vagcom scan and it came up with the following-

1 Fault Found:
00735 - Potentiometer in Positioning Motor for Air recirculation Flap (G143)
30-10 - Open or Short to Plus - Intermittent

Anyone got any ideas? In the current wet weather up here its not exactly safe driving around with a misted up screen.

[xenon]

Sounds like the recirc flap is stuck open in recirc mode. I also think this is also why you had no cooling in the summer. To access the recirc falp motor you will need to remove the govebox. The motor is to the left with a light blue lever attached to it and is mounted on the side of the blower unit. 3 options:

1) Remove motor unit and carefully open up the casing. Inside you will find the potentiometer mentioned in the fault scan along with the motor itself. Try spraying the potentiometer with Isopropyl Alcohol (or similar).

2) Remove the motor completely making sure that the flaps are not in recirc mode.

3) Buy a new motor (approx. £80 I think).

Could also be that the defroster flap is stuck also but as you don't have a fault code for that then I doubt it. You can check the operation of the various flaps while the glovebox is out by watching the control levers move as you select the different options on the climate control.

[Martin F]

Don't overlook a blocked cabin filter. If it's blocked then airflow can be low and one of the signs is struggling to demist the screen.

AMHIK

[weeleigh]

Thanks Xenon. I'll maybe try and take out the glovebox at the weekend for a look.

[jsnmac]

mine did this, all we did was slide something thin into the top vent and disturbed the flap that directs the air upwards. After doing that it never played up anymore. Good luck

[weeleigh]

Thanks for all replies- hopefully I'll get it sorted at the weekend!

[weeleigh]

Just to update this thread- I got it fixed by removing the glovebox and undoing the 2 bolts holding the motor that has the green levers attached to it. By removing the motor it allowed the lever to move, and that seemed to free everything up. I sprayed the lever joints with WD40, reconnected the motor with the bolts and tested the heater.

Voila! Air to the screen vents now. When you press the up arrow on the heater unit with the glovebox out, you can see the lever moving. It wasn't before.

If anyone is a bit scared to remove their glovebox, don't be. It's only 5x 8mm bolts, and the glovebox gently drops down. Easy to put back on as well.

I've posted a photo with the glovebox out, showing the motors that control the airflow. The one with the green lever attached is the one that directs the air to the middle screen vents.

Hope this helps anyone with a similar problem. Cheers.