What is warmed up? (was Re: long distance repair)

[Kershner Wyatt <kwyatt@access.digex.net>]

Greg & Britt wrote:
> 
> Aleksander Mierzwa wrote:
> <snip>
>
> Audi uses a very well designed thermostat. It has  2 valves, works like
> this: Cold engine-water only circulated in engine block, during warm-up
> 1st valve opens allowing water to flow to heater core and auto trans
> cooler(warmer in the winter!) finally opening to radiator when at
> operating temp. The main valve has a rapid opening vs. temp rate when
> temp is close to operating point, as opposed to a cheaper thermostat
> that starts the opening process early. The main valve also has a rubber
> seal on its lip to prevent any water flow to radiator when the
> thermostat is closed.

Where is the coolant temp gauge sensor picking up from?  My Audi A6
seems to take a looooonnnnnggggg time to warm up, but has heat within
1/2 mile in subfreezing weather.  Full warm-up is indicated in about 5
miles or so (highway speeds 50-65). I would like to know whether I
should be concerned about what the guage says or just figure that as
long as I get decent heat, I am doing just fine.

I have noticed that if I manually set the heater fan to run at the
lowest speed, I will speed warm up (according to the gauge) by about 2
miles.  But if it doesn't really have much indication on what the engine
is running at, well, back on full auto I will go.

Any ideas?

Kershner