Subaru SVX 1992 Manual page 973

AUTOMATIC AIR CONDITIONING SYSTEM
[M5175] 4-7
4) Low temperature defrosting control
[When AUTO switch or DEF switch is ON]
The compressor delivery is varied corresponding to the
ambient temperature so that the evaporator outlet air
temperature can be kept within the range of 1 -3°C (34
- 37°F) . When the CIRC switch is OFF, the temperature
is detected by the refrigerant temperature sensor .
Evaporator discharge
temperature
(or refrigerant temperature)
3 (37)
Target
temperature I
1
(34) I
Ambient
I I !
temperature
-5
0 (32)
3 5
°C
(23)
(37) (41) (°F)
C4-444
Fig. 83
Evaporator protection against freezing
[When AUTO switch or DEF switch is ON and CIRC
switch is ON (RECIRC)]
The compressor magnet clutch is turned OFF depend-
ing on the temperature detected by the evaporator
sensor .
CIRC switch "ON"
Evaporator sensor
temp .
Compressor OFF - ON
3 (37) - -
i
I
1 (34)
1
-- ! 1 0'S
T
Ambient
-51(23)
0 1 (32) 3,(37) 5 temp.
(41)
-1 .5
(29) 1
Compressor ON -+ OFF
oC
(°F)
C4-445
Fig . 84
CIRC switch "OFF"
Refrigerant temp . sensor temp .
Compressor OFF -> ON
3 (37)
I
I
1
(34)
I
I .5 (33)_ _ _ --- I Ambient 0
3. (37) 5
temp.
-5 :(23)
-1 .5 :(29) 0 (32)
1 i (41)
I -1 .5 (29) I
i
i
0
C (
0
F)
I ----
--- 5)
(23)
Compressor ON -a OFF
C4-446
Fig . 85
5) Control by engine control unit (MPFI unit) signal
The engine control unit issues a compressor delivery
reduction demanding signal (MPFI unit signal) to the
auto amplifier. The auto amplifier, when receiving this
signal, controls the solenoid actuator current as shown
below .
MPFI signal Solenoid actuator current
A Ordinary temperature control
B 0 .3(A)
C 0 .45(A)
D' 0 .6(A)
E (Compressor
OFF signal)
0(A)
Fault
0.6(A)
MPFI
MPFI
signal IIIII
control
Auto -
amp'
Solenoid
Solenoid
unit
actuator
actuator
current
Compressor
[When AUTO switch or DEF switch is ON and CIRC
Fig. 86
switch is OFF (AUTO)]
The engine control unit (MPFI unit) issues the MPFI
The compressor is turned OFF depending on the tem-
signal as mentioned above to the auto amplifier .
perature detected by the refrigerant temperature sen-
sor .
39