Page 161
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Ventilation fan
Ventilation fan
103
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Saab 900
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Page 162
2
224:
Ventilation fan
Operation
Ventilation fan motor 36 has three speeds and is
controlled from fan selector switch 35.
Switch 35 is supplied from fuse 9, via 29-pole red
connector 152B. The fan speed can be varied by
taking the supply from different points on resistor 74.
When main fan switch 149 is closed, the fan will
always be running, regardless of the position of the
fan selector switch.
Main switch 149 and AC switch 150 are controlled by
the air distribution control. Switch 149 is closed
when the control is in any position except positions 0
and 4§, when it is open (the control is closed). Switch
150 is closed when the control is in position 4). The
fan motor will then receive the full supply and run at
the highest speed.
If resistor 74 is overloaded, the resulting heat will
cause the bimetal switch to close. The positive sup-
ply will be earthed, and fuse 9 will blow. The bimetal
switch will open when it has cooled.
Fault-tracing hints
The ventilation fan will be operative when the ignition
switch is in the drive position.
1. Check fuse 9 and check that the supply to it is
live.
2. Check that the supplies to switch 150 and
switch 35 are live.
3. Turn the switch to different positions and check
that the voltage to the fan motor changes.
4. Check the connectors, cable harnesses and
earth connections.
Saab 900
Page 163
222 ~=Ventilation fan
Locations of components
3
22A
35
36
74
149
150
152B
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Earthing point in the facia
Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
Selector switch for the ventilation fan
in the centre of the facia
Motor for the ventilation fan
behind the right-hand speaker grille
Resistor for ventilation fan
accessible under the left-hand speaker
grille
Main switch for ventilation fan
on the facia, in the air distribution control
(upper contact)
Air distribution switch, AC position
on the facia, in the air distribution control
(lower contact)
29-pole red connector
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing.
The connector is accessible from the inte-
rior of the car
Saab 900
Page 164
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Ventilation fan
223
Components
36
74
149
150
Saab 900
Page 165
224 Air Conditioner (AC) with time-delay relay
Air Conditioner (AC) with time-delay relay
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Saab 900
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Page 166
Air Conditioner (AC) with time-delay relay 225
Operation
Certain cars are equipped with an Air Conditioner
(AC). For a complete description of the wiring for the
lighting of switches on cars for the US, CA and JP
markets, see the section entitled "Lighting for con-
trols, US, CA, JP”.
Compressor and radiator fan motor 37
The AC can be switched on and off by means of AC
switch 169, which is supplied from fuse 6, via
29-pole black connector 152C. When the switch is
depressed, the lamp built into the button will be
supplied directly (not via the resistor), so it will light
up with full intensity. (When the switch is not acti-
vated, the lamp is supplied from the instrument light-
ing rheostat.)
Compressor 170 and ordinary radiator fan 37 are
connected via relay 156, whose contacts are sup-
plied from fuse 25. The relay will be energised when
the following conditions are satisfied:
® Pressure switch 166 is closed, i.e. the refrigerant
pressure is at least 2.8 bar.
e Anti-freeze thermostat (cycling clutch contact)
171 is closed, i.e. the ambient temperature is at
least about +6 °C.
When the relay is energised, the compressor will be
supplied only if temperature switch 168 is closed.
(The switch will open if the engine temperature
should exceed around +115 °C.)
Diode 173, which is connected in parallel with the
compressor, reduces the voltage transients at the
instant when the compressor is switched off.
Delayed connection when starting
Relay 156 is equipped with two time delay functions.
One of them is activated whenever the engine is
being started. Ignition switch 20 (in the start posi-
tion) supplies pin 50, and if switch 169 is then de-
pressed, the energising of the relay and thus starting
of the compressor will be delayed for around 10
seconds, to avoid an excessive load on the battery.
Idling speed compensation and cut-out at full load
There are two systems, i.e. one for cars equipped
with the 16-valve engine and the other for cars with
the 8-valve engine.
On cars with the 16-valve engine, idling speed ad-
justment motor 272, which is controlled by control
unit 200 for the LH fuel injection system, is used for
idling speed compensation. To prevent the engine
speed from falling when the compressor is started at
engine idling speed, the energising of the relay elec-
tronics is delayed, to give the control unit time to
adjust the idling speed.
On cars with the 8-valve engine, solenoid valve 142,
which is always open when the compressor is run-
ning, is used for idling speed compensation.
When the engine is running at full throttle (throttle
open more than 70°), pin TK of the relay will be
earthed through throttle angle transmitter 203, and
the relay will trip the compressor.
LH fuel system 2.2
The control unit receives a signal via relay pin 16
when the time delay of the relay is activated, and it
then starts idling speed compensation. After 0.6
seconds, the relay will be energised and the com-
pressor will start. The relay electronics are supplied
(in the drive position) via pin 15.
LH fuel system 2.4
Control unit 200 receives a signal via relay pin 87B
when the relay is energised, and it then starts idling
speed compensation. The relay electronics are sup-
plied (in the drive position) via pin 15.
AC radiator fan 172
Extra radiator fan 172 for the AC is connected via
relay 155 and is supplied from fuse 6.
The relay coil is supplied from the contacts of relay
156 and from pressure switch 166. The AC radiator
fan thus runs when AC switch 169 is depressed and
pressure switch 166 is closed.
Recirculation valve 38
Recirculation valve 38, which controls the recircula-
tion damper, will be switched on when recirculation
switch 143 is depressed. The switch is supplied from
fuse 6. When the switch is depressed, the lamp built
into the switch will light up with full intensity.
The recirculation valve is also connected across main
switch 149, when the air distribution control is in
position O or ¢» (regardless of the position of switch
143). The supply is taken from fuse 9, via ventilation
fan resistor 74.
Saab 900
Page 167
/ 226 Air Conditioner (AC) with time-delay relay
Fault-tracing hints
As a general rule, the supply to the unit is live when
the ignition switch is in the drive position. If none of
the components are faulty, check the cable har-
nesses, connectors and earth connections.
Compressor and radiator fan motor 37
1. Check fuses 6 and 25 and check that the sup-
plies to AC switch 169 and relay 156 are live.
2. Press the AC switch. Measure the voltage across
pressure switch 166 (the pressure switch
should be closed). Note that refrigerant will
spray out when the pressure switch is discon-
nected. Caution: Risk of frostbite.
3. Check cycling clutch contact 171. (It should
close at +6 °C.)
4. Check that the relay is energised and that the
relay contacts (87 and 87A) are live. If not,
check that the coil/electronics are being sup-
plied from thermostat 171 and from the +15
distribution terminal. When the relay is ener-
gised, terminal 16 should be live. At full throttle,
} terminal TK should be earthed.
5. Check that the supplies to the compressor and
. the radiator fan are live. (Temperature switch
168 should be closed.)
AC radiator fan 172
1. Check fuse 6 and check that the supply to the AC
elke switch and to relay 155 is live.
v
Press the AC switch. Measure the voltage across
pressure switch 166 (the pressure switch
i} should be closed). Note that refrigerant will
i spray out when the pressure switch is discon-
ii nected. Caution: Risk of frostbite.
3. Check that relay 155 is being energised and that
the supply to the AC radiator fan is live.
i Recirculation
|
| 1. Check fuse 6 and check that the supply to recir-
culation switch 143 is live.
2. Press the switch and check that the recirculation
valve is activated.
3. Check fuse 9 and check that the supply to main
switch 149 in the air distribution control is live.
4. When the control is in position O or ¢ », the
recirculation valve should be activated.
Saab 900
Page 168
228 _ Air Conditioner (AC) with time-delay relay
Locations of components
3
C
8
a7
22A
35
37
38
59
60
67
74
118
142
143
149
150
Earthing point in the facia
Earthing point, radiator cross-member
Lighting relay
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Extra rheostat for the lighting of switches
and controls
Fuse holder
in the electrical distribution box, in the en-
gine compartment, on the left-hand wheel
housing
Selector switch for the ventilation fan
inthe centre of the facia
Radiator fan motor (ordinary)
on the right-hand side of the radiator pack-
age
Recirculation valve
in the engine compartment, above the right-
hand wheel housing (1987)
under the facia on the right-hand side, for-
ward of the right-hand A pillar (1988)
2-pole connector
one adjacent to radiator fan 37
one adjacent to AC radiator fan 172
Single-pole connector
at the extreme rear of the engine compart-
ment, at the compressor
6-pole connector
in the engine compartment,
right-hand side, at the air intake
on the
Resistor for ventilation fan
accessible under the left-hand speaker
grille
Relay for the electrically heated rear window
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Solenoid valve for raising the idling speed,
AC
on the engine, on the by-pass hose of the
throttle housing
Recirculation switch, AC
in the centre of the facia
Main switch for ventilation fan
on the facia, in the air distribution control
(upper contact)
Air distribution switch, AC position
on the facia, in the air distribution control
(lower contact)
152B
152C
155
156
158
166
168
169
170
74.
(2
£73
200
201
203
268
270
29-pole red connector
29-pole black connector
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing. The connectors are accessible
from the interior of the car.
Relay for the AC radiator fan
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Relay for the AC compressor
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Negative distribution terminal
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Pressure switch for the AC radiator fan
in the engine compartment, on the drying
agent container, forward of the right-hand
wheel housing
Coolant temperature switch, AC
on the radiator inlet hose, near the distribu-
tor
Switch, AC
in the centre of the facia
Compressor for the AC
at the rear of the engine compartment
Anti-freeze thermostat (cycling clutch con-
tact) for the AC
in the engine compartment, on the right-
hand side of the air conditioner housing
Radiator fan for the AC
on the left-hand side of the radiator pack-
age
Diode for the AC compressor
in the cable harness, at the rear of the valve
cover
Control unit for the LH system
forward of the right-hand front door, below
the facia (behind the trim)
Engine earthing point
at the engine lifting lug
Throttle angle transmitter for the LH fuel
injection system
on the engine throttle housing
Connection for the AC in the back seat (sin-
gle-pole connector 60)
Relay for shift-up indication
in the electrical distribution box in the en-
gine compartment, on the left-hand wheel
housing
Saab 900
Page 169
Air Conditioner (AC) with time-delay relay 229
Components
the en-
{ wheel
essible
‘he en-
wheel
he en-
wheel
1e en-
wheel
Irying
‘-hand i
tribu-
con-
ight-
ack-
alve : a
38 142 143 50
‘low \ =
uel
155 156 | 1166 168 = 169
iin-
bn-
bel
170 171 200
Saab 900
Page 170
Electrically heated front seats
Electrically heated front seats
59
60
59
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117
Saab 900
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