[A4] Fogging Windows...

[thejimrose]

timely question - i just noticed this this past weekend going up to tahoe
and back. i have the exact 'symptoms' - edges of front, and all of rear
windows fog. it's very annoying, i've been wondering if something in the cc
system had failed [flaps, springs, etc] or if there was some other venting
that was not working properly.

I have to totally agree w/ richard below - ac is a dehumidifier, and it
really seems that the a4 is designed to have the cc system in auto all the
time, aka a/c on. if i run the ac the interior dehumidifies in minutes. if i
switch the a/c off it will fog up in 15 minutes. it's frustrating the car
doesn't vent well on it's own, but say la vee.

cracking the sunroof helps immensely in warmer weather, but in the cold/rain
it's not really an option.



> ------------------------------
>
> Message: 9
> Date: Tue, 15 Jan 2008 11:54:33 -0500
> From: "Richard Hurt" <rnhurt at gmail.com>
> Subject: Re: [A4] Fogging Windows...
> To: "A4 Mailing List" <a4 at audifans.com>
> Message-ID:
>        <712ba87c0801150854q5e1fa4d3laca3932a9d7f22f2 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Absolutely!  You have to use the A/C and outside air in order to remove
> moisture from the air.  Cooling the air has the side effect of removing
> moisture from it as well.  Ever notice water dripping out of the car next
> to
> you at the stop light in the summer?  That's the A/C doing it's job.  By
> the
> same token it is necessary to have fresh (cold / dry) air coming in from
> the
> outside.  As you respire you give off a lot of moisture (just breath on a
> mirror) and if you just recycle that air the moisture won't go away.
>
> In short, I don't think you have any leaks at all.  You would definitely
> notice a heater core leak; the sickly sweet smell and film that sticks to
> the inside of the windows is unmistakable.  In fact, my A4 will fog up
> quite
> a bit in rainy weather if I don't turn the A/C on.  For a while I was like
> you and tried to save fuel by turning off the compressor when I didn't
> need
> it, but eventually I just set it on "Auto" and let it do it's thing.  It
> makes the best decision most of the time.  I find it kind of ironic that I
> have to re-heat the air coming out of the vents when I run the A/C in the
> winter, but that's physics for you.  :)
>
> Later...
>  Richard
>
>