Saab 900 Service Manual page 14

854-2 Heating and ventilation system, air conditioning system
Saab 900
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The heating system is controlled as follows:
1 Vacuum-controlled dampers for guiding the
flow of air through the system.
2 Thermostatically controlled, manually ad-
justable temperature control valve for con-
trolling the flow of engine coolant through
the heat exchanger.
3 Switch for controlling the fan speed.
The fan switch can be set for three different fan
speeds. The switch has no "off" position, and the
fan will therefore always be running, whenever
the vacuum distributor is operative. When the air
distribution control is set to "0", the supply cir-
cuit to the fan will be opened, regardless of the
fan switch position. These functions are control-
led by microswitches actuated by the air distribu-
tion control knob.
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1 Air intake
2 Filter
3 Fan motor
4 Heat exchanger
5 Temperature control valve
Positions~and ~
of the air distribution
control are intended for the air conditioning unit
that can be incorporated into the ordinary heat-
ing and ventilation system. In cars not equipped
with an air conditioning system, these positions
are used only for supplying fresh air.
As from the 1984 models, cars with an air condi-
tioning system includes a manually controlled
air recirculation feature. Air recirculation is
started automatically when the air distribution
control is set to ~
Note
Air recirculation should not be used in cold·
weather, since it may give rise to misting and
frosting of the windows.
7
9
6 Air distribution control
7
Vacuum servo, single-stage
8 Vacuum servo, tWo-stage
9 Vacuum-controlled air dampers