faulty flaps

[bobsimes]

i have had a problem with the aircon/heating for a while(2002 a2 1.4tdi with aircon) and recently had the opportunity to replace the servo which i thought was faulty.

the problem i have is when i turn the temp up the air coming out of the vents will alternate hot/cold and i can hear the servo moving (temp servo bottom one to the left of the radio din unit) i have changed this servo and the one above it, although it has now stopped moving of its own accord there is no change in what it was doing, i have also changed the temp sensor which is located behind the radio and i am still having the same problem of alternating cold/warm air when i turn the temp up, ps its fine when set on cold it only happens when i dial the temp up over 70 ish.

i have tried a vagcom reset , it lets me log in to auto/hvac 04 ans starts flap reset procedure the panel in the car goes into reset mode but after about 10 seconds in the flap boxes which are supposed to reset to 0 (in vagcom) it shows error somthing like 07? in brown writing across each of the flap boxes, i then have to turn off the ignition to reset the air con unit.

any ideas??

also does anyone know the correct positioning of the flaps on re install, is there notches for correct alignment of the flaps and servo's?? as the elsawin diagram does not seem correct for my model? (yes i have searched across elsawin for the a2 2002,3,4,5 and all diagrams are the same.)

simon

 

[fbi]

Hi Simon,
I have the same problem. So far, it is not that ennoying, but it can turn worse...
Anyway, I plan to fix that in the future...
From what I understood from the little research I made on the subject, the "servo-controlled flaps" that are related to the various air outlets are not the culprits. The problem sits more upstream. It is the device that mixes cold air (from outside or aircon) and hot air form the heater matrix. This device is also servocontrolled. If it pulses cold/hot/cold... air, it is because its flap cannot stay at the position at which it gets instructions to stay, resulting in a too cold or too hot mixture. So, as it functions in closed loop, the signal sent to the climate ECU results in an instruction saying that the flap must be moved in the other way, and so on.
That device sits at the bottom left of the dash (at least in a LHD).
I've read that it could be "trained" with VAG Com, you can make it move from fully open to fully close several times, and sometimes that can cure the fault. Not tried so far...
Dismantling the device and applying a signal (current) to move the flap from one extreme position to the other can "repair" it aswell.
That's just what I remember....
I had bookmarked some links last year, especially on the German forum, but my laptop has been stolen and I had no backup of my favourites.
The A4 (old) also suffers from that, so you may have more chance in looking for A4 fixes.

Sorry for my bad English

Please keep us informed if you try something, and above all if you succeed to fix it

 

[bobsimes]

servo

yes this is the servo i have changed the one that mixes the air but i am still having problems and cannot get vagcom to complete the reset procedure as it shows an error towards the end of the reset procedure.

 

[fbi]

oops, sorry I didn't catch that you were already at the last stage of fixing this probelm.
What's the price of that servo, btw ?

As I said, try to broaden your search to A4 forums, you may find the answser...