Porsche 928 S 1986 Driver Manual page 40

Automatically controlled air
conditioning
The automatic system controls the passenger
compartment temperature in accordance with
the program you have chosen and the pas-
senger compartment temperature set with the
slide.
The passenger compartment temperature is
reached as quickly as possible and is kept
constant under changing climatic conditions.
It is not normally necessary to re-adjust the
temperature.
36
Since the heating effect is dependent on the
coolant temperature, full heating is not ob-
tained until the engine is at operating tempe-
rature.
Hot and cold air is automatically blended by
air mixer flaps which are operated by a servo
motor.
Temperature fluctuations are quickly detected
and the servo motor is controlled accordingly.
Changes in temperature are detected by way
of the passenger compartment temperature
(temperature sensor behind the perforated
panel) and the outside temperature (tempe-
rature sensor in wheel housing).
"AC" push-button switch
In the hot season the supply of fresh air is not
always sufficient to reach the desired pas-
senger compartment temperature.
To cool the air to the level set with the tempe-
rature slide, the air conditioning compressor
must be switched on by pressing the AC switch
in the centre console (arrow).
If cooling of the air is not necessary in the cold
season, the air conditioner should not be
switched on in order to save fuel.
In the case of sudden changes in temperature
the system controls the supply of hot and fresh
air and, with the compressor on, also controls
the supply of refrigerated air until the set tem-
perature has been reached again.
The air conditioning only functions with the
engine running. The cooling efficiency is de-
pendent on engine revolutions. If more cool-
ing is required it is necessary - especially in
city or stop go conditions - to increase engine
rpm.
Proper operation of the automatic air condi-
tioner is guaranteed only if the windows and
the roof are closed and the side vents as well
as the central vent are fully open.
If the vehicle has been standing for a long time
in direct sunlight, it is recommended that the
air conditioning be turned on with the windows
open to provide through ventilation.
When the air conditioner is switched on addi-
tional cooled air is fed via a vent to the glove
compartment.
In damp weather it is advisable, even at low
outside temperatures, to switch on the air con-
ditioner. This dries the air and prevents the
windows from misting up.