Mercedes-Benz 300D 2.5 1990 Owner's Manual page 23

Temperature Selection
The desired interior tem perature can be selected
by rotating the temperature selector. The selected
temperature is reached as quickly as possible and
maintained. A basic setting of 72°F (22°C) is
recommended.
Note:
If the temperature regulation becomes defectives, move
the temperature selector "MIN" or "MAX" end positions to
turn heat on or off.
"MIN" = Heat off
"MAX" = Heat on
Have the system checked at your authorized
MERCEDES-BENZ dealer as soon as possible.
Air Recirculation
Press symbol side of switch = the air recirculation
«
mode is engaged. The indicator lamp in the switch
lights up.
This mode can be selected to prevent annoying
odors or dust from entering the car's interior.
At high outside temperatures, the system automatically
engages the air recirculation mode, thereby increasing the
cooling capacity performance.
The recirculated air mode will be automatically switched
off after approximately 30 minutes of operation at outside
tem peratures above approximately 7°C (45°F) and after
approximately 5 minutes at outside tem peratures below
approximately 7°C (45°F).
If the windows begin to fog up from the inside, switch
from recirculated air back to fresh air by pressing the
lower half of the air recirculation switch (the indicator
lamp in the switch goes out).
Note:
It is not possible to switch to recirculated air if button Q
or jg jis depressed.