Re: A4 climate control gripes

[Elliott Potter <epotter@abraxis.com>]

Chris Newbold wrote:
> 
> Josh Pinkert wrote:
> >
> > At 10:05 PM 1/13/98 -0500, Tom Haapanen wrote:
> > >My A4 allows me to turn on recirc even when the heater is on (which it
> > >is pretty much all the time right now!).  Could this be a change from
> > >'97 to '98?
> >
> > Hmm...my '98 doesn't allow me to do this.  I wish, though :D
> 
> [...]
> Once the outside temp. drops low enough that the compressor is shut off,
> then recirculation is disabled.
> 
> As I understand it, this was done to prevent the windows from fogging
> (due to
> excess moisture build-up inside without drying effect of A/C and lack of
> outside air).
>  
> However, it has the annoying side-effect of not letting you engage
> recirculation
> to avoid asphixiation by dead skunks, traffic jams in tunnels, etc.
> 
> Of course, many also cure the inability to engage the A/C compressor in
> very
> cold weather to defrost the windows, too...
> 
> -Chris
> 1993 90CS 63k

I thought a little about this, and had some comments/ideas.

First off, I'm assuming that the routing for the CC system goes like
this:

    \__________________/
A -> ~   ()()()   {      B ->
    /-- ---------------\
      | |_________________
      \___________________ <- C



where "A" is the outside air intake, "~" is the flap that closes when
you hit recirculate, "()()()" is the A/C coil, and "{" is the fan (I
suppose the fan and A/C coils could be interchanged, it doesn't really
matter here).
So when Recirc. is activated, air from inside the car goes from C back
into the system between the recirc. flap and the coils, then back across
the coils.

If this is the case, then it might be possible to fiddle with the CC
computer  so that it can handle the following requests:

-If it's too cold outside and the recirc. flap is open (fresh air coming
in), the compressor won't turn on as normal.
-If it's too cold outside and the recirc. flap is closed, the compressor
will turn on because presumably the air coming into the system from the
cabin is warm enough that the coils won't ice over, and
-Oh yea, if the compressor isn't turned on, the recirc. flap will still
close.

Possibly, if it's too cold outside and you want to do a quick defrost,
you could hit the A/C and the recirc. flap would close automatically.



-- 
Elliott

"I love deadlines. I like the whooshing sound they make as they fly by." 
( Douglas Adams )