It has a variable speed fan, speed selected by switching a resistor set
just like a manual HVAC in a Benz. When the temp dial is set to the
minimum, it clicks -- this is an override position, at least on the
later systems, that switches off any reheat via the heater core and
servo or monovalve to provide maximum cooling with no temp control.
Fan speed will drop to minimum and very cold air will be delivered so
long as the temp dial is all the way down. Off the click stop you will
have re-heat and the temp will be controlled at around 60-65F.
On the later systems, fan speed is infinitely variable via a transistor
switching system, and the fan speed can get VERY low if the low speed
fan button is pushed.
Remember, this is an automatic temperature control system, not a
"temperature of delivered air" system. It will maintain cabin temp to
the selected temperature within mechanical limits.
Defrost and full heat (click stop at the highest tempt setting) do
exactly the same with with heat -- full heater core flow reguardless of
cabin temp.
Peter
