Frosted by defroster...

[Kneale Brownson]

Sounds like you have the classic failed recirculation door syndrome, 
Scott.  On Type 44 cars, and I presume, on your 100, there's a door between 
the cabin and the HVAC  system's air intake point under the hood that is 
supposed to remain closed during cold weather operation so that you're not 
putting mixing warm air from the cabin with cold air in the intake 
plenum.   The typical failure is for the spring that holds the door closed 
(unless the air conditioner calls for it to be open) slices through the POS 
plastic bar to which it's mounted, so the door hangs open instead of being 
pulled closed by the spring.  When the A/C calls for the door to be open 
(only when it's operating so that cooled air from the cabin is being 
recirculated back to the cabin after being recooled), a vacuum-operated 
servo pushes it open against the spring's return pressure.  You can tape 
the door closed for the winter or work on a repair so you won't stress the 
A/C next spring.


At 11:49 AM 11/27/2000 -0800, Fisher, Scott wrote:

>Well, our 1500+ mile trip last week through the Siskiyous and the Willamette
>River Valley of Oregon went off flawlessly, the '93 100CSQ worked like a
>dream.
>
>At times that dream was more like one of those where you are trying to force
>yourself to wake up before the cannibal ghouls drag you into an open grave
>and devour your flesh -- but I'm getting ahead of myself.
>
>After my wife's confusion over the central locking behavior (which we
>figured out with the list's help, and which worked flawlessly), we took the
>owner's manual (you can't RFTM if you don't have TFM to R) in the event of
>other curiosities.  A good thing too.
>
>North of Yreka, where the road starts to climb, I noticed that the outside
>temperature started dropping.  We'd been comfortably ensconced at about 70
>degrees for the whole trip, in spite of the outside sensor reading 40, then
>39, then 38 degrees.  I had been making really great time, until I happened
>to notice that the outside temp dropped to 35 degrees.
>
>And all hell broke loose inside the car.  It was as if someone had set off a
>smoke grenade in the interior -- the windows became opaque almost
>immediately, with only a very small patch right in front of me (fortunately)
>to peer out of.  Not something you want to have happen suddenly and without
>warning at 80 mph on a winding mountain road.
>
>Because I'm not only a frood who knows where his towel is but *also* one who
>keeps extra towels on hand at all times, I took one of the small hand towels
>we'd placed in the front seat and wiped the window for visibility, but it
>wasn't getting better.  I slowed significantly as I wiped the windows (we
>were climbing the foot of Mt. Shasta at the time), asking my poor wife to
>get the manual out of the glovebox.
>
>The glovebox wouldn't open.
>
>She jiggled it, wiggled it, and pried it.
>
>The lock cylinder fell out.
>
>Fortunately, a few miles later, we pulled off the side of the road so that
>the children could have a snowball fight.  They had great fun, ganging up on
>each other, ganging up on me, yelping about cold hands as they scooped up
>the light, dry snow and hurled it at one another.
>
>I reinserted the lock cylinder, opened the glovebox, and extracted TFM.
>Yes, I'd been pushing the right buttons to invoke defrosting.  Yes, the A/C
>compressor comes on automatically when you press the defrost icon, and you
>can tell it's on because of the snowflake icon on the climate control.  And
>then, sure enough, there it is in black and white: on cars with automatic
>climate control (such as ours), the A/C compressor automatically shuts off
>at 35 degrees F *AND CANNOT BE RESTARTED, EVEN BY PRESSING THE COMPRESSOR
>BUTTON* until the temperature climbs (in practice, till it reaches nearly 40
>degrees).
>
>So...
>
>How do I defeat this insanity?  We *are* moving to Oregon over the next 2-3
>months and will therefore have occasion to drive the car often in sub-35
>degree weather, and while we've discovered a workaround (drop the windows at
>75+ mph for ten seconds or so to chill the interior, then close back up), I
>hate this.  It comes pretty close to making the car undrivable when it
>happens, though being able to expect it helps immensely with preparation
>(dishtowels and/or squeegees).  But if anybody had offered me and my wife
>ten bucks for the Audi and a ride to a used-car lot on Saturday the 18th...
>well, somebody might have picked up a really great car for cheap.  I hate
>most "we're smarter than you" details on most modern cars, and in particular
>I dislike the climate controls on any car that doesn't let me control vent
>output, temperature, A/C compressor, and fan individually and exactly... but
>this just crossed the Rubicon for me.
>
>There's gotta be a wire we can cut or jumper or a relay we can fiddle,
>right?  Or is there some other way to deal with this, short of selling the
>car?
>
>--Scott Fisher
>   Somewhere between Sunnyvale, CA and Tualatin, OR
>   1983 Audi CGT *fully manual A-C/heat/defrost controls*
>   1993 Audi 100CSQ (don't get me started)
>
>