Porsche 928 ST1991 Owner's Manual page 51

Automatic climate control
WARNING
• Familiarize yourself thoroughly with the
proper use and function of the ventila-
tion/heating, defogging/defrosting and
the air conditioning system.
• For safe driving it is extremely important
that you follow the operating instruc-
tions in this manual. If in doubt, consult
with your Porsche dealer.
• Maximum heating output and fast de-
frosting can be obtained only after the
engine has reached normal operating
temperature.
50
This system automatically controls the air
flow distribution and the temperature level
inside the car according to the occupants
wishes. The distribution and mixture of cool
and warm air is electrically regulated and
kept constant, regardless of weather condi-
tions.
Servomotor-controlled air mixing valves au-
tomatically mix the cold and warm air.
The temperature inside the vehicle (tempera-
ture sensor behind the screen mask) and
outside the vehicle (temperature sensor in
the wheel box) are used for quick identifica-
tion of temperature fluctuations and control
of the servomotor.
"AC" pressure switch
When the weather is warm, supplying of
fresh air is not always enough to attain the
desired temperature within the car.
First set the temperature desired using the
temperature lever. Then switch on the air
conditioner by pressing the AC switch in the
center console (arrow).
If no cooling of the air is required in transi-
tional or colder seasons, the air conditioner
should not be switched on due to considera-
tions of fuel economy.
With sudden fluctuations in temperature, the
automatic system regulates the control of
warm air, fresh air, and, if the air conditioner
compressor has been switched on, the sup-
ply of cooling air until the preset inside temp-
erature is reached.
The air conditioner works only when the en-
gine is running, The higher the engine rpm,
the more intensive the cooling effect. Air
from inside the car is drawn through the
evaporator for cooling and then reenters the
car interior through the air outlets.
Proper operation of the air conditioner is
guaranteed only if the windows and roof are
closed and the outlet nozzles at the side and
the center are fully opened.
If the vehicle has been standing for a fairly
long time in intense sunlight, it is recom-
mended that the inside of the vehicle be
thoroughly ventilated by opening the car
windows and switching on the air con-
ditioner.
When the air conditioner is switched on, ad-
ditional cooled air reaches the glove com-
partment through a nozzle.
In damp weather it is recommended to
switch on the air conditioner, even if the out-
side temperature is low. This dehumidifies
the air and prevents the windshield from fog-
ging up.