Does anyone with a modern (2004) MB fitted with the Thermotronic
(intelligent) Air Conditioning system (not the Thermatic AC system)
know how to make it supply fresh air from the outside?
I have studied the OM in detail, and I can find no way to achieve this
very simple function. Apart from opening the windows/sunroof that is.
I thought that I had defeated the 'brain' at one stage by setting the
internal temperature control to the indicated external temperature,
but all that achieves is the blower stops running...
Surely this normal requirement has not been overlooked. Or have I
THERMOTRONIC normally uses fresh air from the outside.
Have you already tried to switch-off everything (_auto_
buttons and _a/c_ button)?
As at higher outside temperatures air-recirculation mode
is activated automatically, in such a situation deactivate
it then by pressing the air-recirculation mode button (car
symbol with circular arrow inside, indicator lamp in the
button lights if air-reciculation mode is active).
Now there should be no automatic cooling or heating (and
no air-dehumidification) - you can control the amount of
air coming in by pressing the buttons with the big fan
symbol (increases airflow) and small fan symbol (decreases
That should give you fresh air from the outside only,
without any heating/cooling/air-dehumidification.
And be sure to set the air distribution to the desired
mode by using the two thumbwheels (around the _auto_
buttons) and to open the air vents by use of their
thumbwheels (4 altogether).
Does that help?
Yes, that seemed to do the trick, That's with a red light showing on
the AC OFF switch, and no Auto red lights.
(why didn't MB call it the AC ON switch, like everyone else?)
Those two Auto red lights seem to have a mind of their own. A simple
press doesn't always extinguish them. A rotation seems to work.
There is also the word Auto on the blower speed display. That one
goes off as you reduce the blower speed manually. Is that indicating
the same information as the red lights in the 2 rotary switches?
I realise that with an automatic control system like this, you can't
fiddle with the knobs and expect immediate results. It takes time to
stabilize. Overall, it's a bit too smart IMHO.
Thanks for the response.
FWIW I have a CLK cab W208 (2001) with what i think is called ACC (auto
The red auto light go off -- IIRC -- when I fiddle with fan speed switch.
It seems you have a different arrangement. I think you have a newer
generation as I have no knobs with lights.
For direct contact replace nospam with schmetterling
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