Not sure on that specific series, but on other MB series it works that
way. Does the owner's manual say anything? It would seem
reasonable for it to go to max heat. Normally whatever mode the
system is set to, some bleed air goes to the windshield vents to keep
it defogged, frost free, etc. So, if you activate DEFROST, I think
the assumption is you have an immediate problem and need it done
ASAP. So, it puts most of the air up there and defaults to HOT.
Yes, it is split between the windshield and floor in winter season... you do
want heat in the car... so it should not be an issue. You can also control
the fan speed too. The car will never get hotter than the temperature you
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