Mercedes-Benz 190 E 2.3-16 201 1987 Owner's Manual page 29

Q Press for fresh air ventilation or air conditioning.
For taking in fresh air or during air conditioner operation,
the air is directed to outlets (5) and (7). Adjust the air flow
with levers (6) and (8) respectively as desired.
B Press to shut off system.
Fresh air into the vehicle is shut off. Do not drive the
vehicle with this setting for long periods with windows and
sliding roof closed since the vehicle's normal interior air­
flow will be disrupted.