Re: type 44->a6/100 CC update info(long, but worth it!)

["Graydon D. Stuckey" <graydon@apollo.kettering.edu>]

On Fri, 4 Dec 1998, Brett Dikeman wrote:

> No...we don't want to go to the rotary knobs, which are only on the lowest 
> model 100's.

If you get a chance, sit in (or drive) an Aurora.  This car has, I think, 
the best control head of any car on the market.  It gives you control 
over the mode and the fan speed in either auto or manual mode.  The mode 
and fan controls are large rotary knobs which turn continuously.  They 
are not pots.  They have probably 40 or 50 detents around their 
perimeter, so there is excellent tactile feedback to let you know you're 
turning it.  If you want to go auto, you simply push the rotary buttons.

The New Seville is also very good, but I think I like the Aurora control 
head better.

> heads are definately NOT.  The a6/100 unit is:
> -much more intelligent
> -uses a second temp sensor

The '86 5000 uses two outside temperature sensors.  Is that what you are 
referring to?  The second temp sensor is in the plenum, which is 
potentially a great place to measure outside temp under certain around 
town driving conditions.   I spent some time a few weeks ago with the 
controls engineer in our department doing nothing but developmnet of the 
algorhythm that determines whether or not the control head believes the 
outside temp sensor.  If you're in heavy traffic, there is enough heat 
soak forward that the engine heat can confuse the temp sensor.  Audi's 
plenum temp sensor reduces that problem.

> -has a seperate recirculate button(a SEVERELY lacking feature of the Delco 
> unit.)

That is definitely a desireable feature.

> -has a "sexier", more modern look that matches the interior of the 200q20v 
> better(they updated everything, down to the window switches, but didn't 
> update the CC unit.)

This is true, and I don't like the tiny litle buttons on the earlier 
Control head.  And, if the contacts get dirty on the old head, the 
buttons don't always work.

> -I have an idea to wire the new unit to only run the radiator fan when it 
> is -needed-.  Right now, the fan runs constantly, which is a huge waste of 
> energy and taxes the already weak electrical system.  The newer unit only 
> runs the radiator fan when a certain pressure switch triggers(but it might 
> require opening the A/C system, so that probably won't work.

I'd simply install a pressure switch in the high pressure line of the AC 
system.  Yes, you'd have to evacuate the refrigerant, but that would be a 
slick way to stop the fan when it isn't needed.

Later,
Graydon D. Stuckey
'86 Audi 5000 CS Quattro - For Sale - Best offer over $5000.00
0 - 60mph in 5.5 seconds!
email for details