87 5KCSTQ How to shorten afterrun time/battery drain

[Ken]

Hello,

Lee, you make it sound like this mod somehow disconnects disables something.  I didn't read where it did anything like that.

Where's the trouble gonna come from?  Seems like it would only help, by lowering the temps while driving.  What's wrong with that?

Perhaps you misunderstood one of the parts you didn't quote:

"Properly used, manually initiated cooling will allow the afterrun system to come on only in extreme situations, when you really need it, rather than every time you use the car in hot weather."

I take that to mean that the stock system functions as designed, but after this mod it will never NEED to come on at all, except for extreme situations (where the manual activation of the hurricane mode prior to arriving at the destination wasn't enough)

Sounds like a great mod to me.  I love to have more control over my car.

Ken

p.s.  Here's the rest of the post, where it describes what the mod is.  It does read to me like manual activation and stock functioning are mutually exclusive.  If I'm wrong I'm sure someone will tell me.

"The 3rd stage fan relay is under the instrument panel. This provides easy
access to implement a manual switch that allows the driver to decide when to turn on the cooling fan to "dump heat" from the cooling system.

Any 12V single pull single throw panel-mount switch will work. You might
want a reasonably attractive one if you install it in a rather visible
location. I installed mine under the leftmost AC vent on the dashboard
(directly to the left of the auxiliary relay panel access door) for easy
access but still a relatively unobtrusive location. I used a rectangular
plastic affair thoughtfully provided by Blau with my last eurolight wiring
harness. It remained unused, since I wired the H3s to come on with the
brights.

The 3rd stage relay has some rather beefy wires running to it, but you don't need to access them. I put a tap (commonly used by alarm and radio
installers - I got mine at Pep Boys) into the green wire supplying the 12V
signal to trigger the relay and ran the resulting signal line to one side of the switch. I found a source of 12V in a common red connector with several spare connections with protruding spade lugs pretty much directly under the center of the instrument cluster. I simply attached a female spade lug to a supply wire, attached one end to the 12V source and the other end to the other terminal of the switch. Voila, instant control of the 3rd stage fan.

No muss, no fuss. Since the switch was rectangular plastic and is held in
place by tabs at either end, I drilled two appropriately sized holes and
shaped the resulting oval into a rectangle with a wood rasp. After pushing
the switch into its new rectangular home, the result was a tidy installation that is flush with the panel but easy to find."

Lee Levitt lee at wheelman.com wrote:
>
> Paul Meyers <paul.meyers at citrix.com> writes:
>
> This is an idea I got from a lister several years ago and finally
> got around to implementing. I'm so happy with it that I wanted to repost
> it to a (potentially) new crop of Audi fans.
>
> > The typical application is a commute home on the freeway on a
> > hot day with the AC on full. On exiting to take city streets
> > (read stop and go traffic) to get home, the temperature rises
> > dramatically. You pull in the driveway and the afterrun system
> > comes on and stays on for what seems like a half hour,
> > depleting battery charge and maybe even requiring a
> > preventative battery charging once a week to keep the charge
> > up, especially if you do a lot of short trips in hot weather.
> >
> > Solution: install a manual switch on the dashboard to turn the
> > cooling fan to "hurricaine mode" when exiting the freeway, so
> > that, by the time you get home, the engine is cooled down to
> > the normal temperature range.
>
> This seems like a bad idea to me. Audi designed the afterrun pump and
> fan to cool the engine down after shutoff, to keep the engine from
> heatsoaking. Running the cooling fan prior to shutdown will not keep
> this from happening.
>
> We had a problem with our '90 200T, which ran the afterrun pump and fan
> after *every* run, rather than only after the engine got sufficiently
> warm. After a week of short trips, the battery would be exhausted as it
> wouldn't get enough time to recharge on the short trips.
>
> We ended up replacing a thermal switch that was defective and everything
> was fine.
>
> The system is designed to run about 5 minutes, when necessary. This is
> not a big deal for a battery in good condition, and I'd certainly rather
> replace a battery every so often rather than a turbo or a block or a
> head.
>
> IMCO, you're just asking for trouble with this mod.
>
> Lee