Niar

Hey!

Which fan flap regulates the air it blows, when the vehicle speed gets higher?

There's not much air coming out, when the speed gets higher. The air amount coming out is so minimal that the windscreen will get easily foggy, when the weather is moist/rainy (doesn't matter what the fan speed is set). Only solution to unfog the windscreen is to lower the speed. It seems like there's some kind of a flap that instantly almost closes when I get on the highway. In the city limits it's OK, blows fine. And when it isn't working correctly, it sound like it's blowing air against something (like said, i suspect some flap) and won't let all the possible air out to the cabin.

I have investigated it from other mechanics/electrics, and they have said that Audi has some kind of a flap that regulates it accourding to vehicle's speed. None of them assured that this "flap" is THE problem and where that flap is, but said that nonetheless I should look into it.

And btw, it has one more anomaly. If I spray washer fluid on the windscreen on highway, for a moment it starts working correlty again, until it finishes its "washing mode" or whatever it's called.

So now here I am. If someone know which of these flaps is that "speed regulating" flap or has any other idea, please let me know! I have searched all forums (even Estonians audi forum , I'm from there btw), no one couldn't give me a solid solution.

Audi A4 B6 2.5Q 2003

Thanks.

david9999

First thing I would do is get a vagcom and check for codes in HVAC.

Niar

Yea... did that. Done also several restart on the climate bloc for assurance, nothing useful came up.

Steamboat

As far as I know, in a B6 A4, there is no HVAC flap that actuates based on the speed of the vehicle.

When you notice that there is little air coming out of the defroster, is the defroster button on the HVAC unit selected?

Niar

If I push the defroster button, the outcoming air amount does not change (it's the same as with defroster not on). Only thing that changes is the sound, sounf of the air blowing even harder against something.
And that kind of situation includes all the other buttons. Temp higher-lower, fan speed higher-lower, and all the other buttons... nothing.

The weird thing is that if I spray windscreen washing fluid, then it starts working for a little time... so in theory that means that mechanically it should be working, but there is just some kind of electronical part interfering it's normal operation. But if there isn't any flap that actuates based on the speed of the vehicle , then what is it that isn't working correctly?

A4Audi4Fun

Very weird VCDS doesn't show any codes; you could also try the VCDS test mode to make sure all the motors actually work.
Failing that, remove the glovebox so that you can see all the different motors controlling the HVAC system; then push the various climate control buttons and make sure at least one motor operates; if no motors are seen to move, the issue might then be with the actual HVAC control module.

david9999

Have you checked the air filter? Sounds like something is blocking the air intake, like a bunch of leaves.

Niar

david9999 I have checked the air filter, even got a new one, like every year, but this problem has a occured for like... 3 years maybe now( ?). Nothing is or was there blocking the air intake.

A4Audi4Fun Did that just before. But the problem is that this anomaly appears only when the outside temperature is low, like below +10C or something. Right now it's +20 C degrees here and everything works like a charm. All the motors operated like they should when i drive. But that's the thing, I need to know what kind of a motor is regulating itself according to speed and outside temperature...

david9999

I must admit I am at a loss.
Could it be that the fan is slipping?

Niar

I don't think so. If so, then it would do the same in every weather or temperature...