LEXUS SC400 1991 Service Workshop Manual

Blower Fan Speed Control System
(When AUTO Switch is ON)
(a) The desired temperature is set using the TEMP switch.
(b) From the input signals (room temperature sensor, ambient temperature sensor and solar sensor) and thetemperature setting, the air conditioner control ECU determines the air flow volume\
and outputs signals
to the power transistor.
(c) When it receives signals from the ECU, the power transistor increases or red\
uces the blower motor speed to control the air flow volume.
(When AUTO Switch is OFF)
The ECU turns the power transistor increasing or reducing the blower mot\
or speed fixing the air flow volume
in accordance with the position of the Manual switch. AC±10
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AIR CONDITIONING SYSTEM Description
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Air Flow Mode Control System
(When the AUTO Switch is ON)
(a) The desired temperature is set using the TEMP switch.
(b) From the input signals (room temperature sensor, ambient temperature sensor and solar sensor) and thetemperature setting, the air conditioner control ECU determines the air flow mode a\
nd outputs signals to
the mode servomotor and max cool servomotor.
(c) When it receives signals from the ECU, the servomotors open or close each of\
the dampers to change the air flow mode.
(When the AUTO Switch is OFF)
The ECU fixes the air flow mode in accordance with the Manual switch pos\
ition.
(When the Engine is Cold)
If the Mode is set on B/L or FOOT, the ECU forcedly changes the air vent to DEF if cold signals are input from
the water temperature sensor.
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AIR CONDITIONING SYSTEM DescriptionAC±11
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Air Inlet Control System
(When the AUTO Switch is ON)
(a) The desired temperature is set using the TEMP switch.
(b) From the input signals (room temperature sensor, ambient temperature sensor and solar sensor) and thetemperature setting, the air conditioner control ECU determines the air \
inlet and outputs signals to the air
inlet servomotor assembly.
(c) When it receives signals from the ECU, the air inlet servomotor opens or clo\
ses the damper to change the air inlet. When the air inlet is changed to the desired setting, it is detected by the air inlet damper p\
osition
sensor and the ECU stops the servomotor.
HINT: If the Mode switch is set on DEF, the ECU forcedly changes the air inlet to FRS.
(When the AUTO Switch is OFF)
The ECU fixes the air inlet according to the position of the manual swit\
ch. AC±12
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AIR CONDITIONING SYSTEM Description
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Part No.Part NameNote
07110-58011
(07117-58010)
(07117-78011)
(07117-88013)
(07117-88022)
(07117-88040)
07110-58040
07112-66040
07112-76060
07114-82020
07117-48050
Air Conditioner
Service Tool Set
(Refrigerant Drum
Service Valve)
(Refrigerant
Charging Gauge)
(Refrigerant
Charging Hose)
(Refrigerant
Charging Hose)
(Refrigerant
Charging Hose)
(Stop Valve)
Charging Hose Kit.
w/Stop Valve
Magnetic Clutch
Stopper
Magnetic Clutch
Remover
Snap Ring Pliers
Vacuum Pump Assy
Orange Color
If you require a stop valve, please order this kit.
Rated voltage AC220V
Illustration
IllustrationPart No.Part NameNote
09082-00015TOYOTA
Electrical TesterMeasure voltage currant and resistance
Blue Color
Green Color
PREPARATION
SST (SPECIAL SERVICE TOOLS)
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AIR CONDITIONING SYSTEM PreparationAC±13
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EQUIPMENT
 Part Name\
 \
Note
 

Voltmeter\
 
\

\
Measures voltage 

Ammeter
\
 
\

\
Measures current
 Ohmmeter\
 \
Measures resistance
LUBRICANT
ItemCapacityClassificationItemccfl. ozClassification
Compressor oil
When replacing receiver
When replacing condenser
When replacing evaporator
20
40±50
40±500.7
1.4±1.7
1.4±1.7
ND OIL 6,
SUNISO No. 5GS or equivalent
AC±14±
AIR CONDITIONING SYSTEM Preparation Cooling System
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USE OF MANIFOLD GAUGE SET
INSTALLATION OF MANIFOLD GAUGE
SET
HINT: To prevent releasing refrigerant, use charging hoses
with a stop valve when installing the manifold gauge set to
service valves on the refrigerant line.
1. CONNECT CHARGING HOSES WITH A STOP VALVE TO MANIFOLD GAUGE SET
Tighten the nuts by hand.
CAUTION:
wDo not connect the wrong hoses to the high
pressure and the low pressure sides.
w To prevent loosening the nuts, do not apply
compressor oil to seat of the connection.
2. CLOSE HAND VALVES OF BOTH STOP VALVES
3. CLOSE BOTH HAND VALVES OF MANIFOLD GAUGE SET
4. REMOVE CAPS FROM SERVICE VALVES ON REFRIGERANT LINE
5. CONNECT STOP VALVES TO SERVICE VALVES Tighten the nuts by hand.
CAUTION:
wDo not connect the wrong hoses to the high
pressure and the low pressure sides.
w To prevent loosening the nuts, do not apply
compressor oil to seat of the connection.
6. OPEN HAND VALVES OF BOTH STOP VALVES
REMOVAL OF MANIFOLD GAUGE SET
1. CLOSE BOTH HAND VALVES OF MANIFOLD GAUGE SET
2. CLOSE HAND VALVES OF BOTH STOP VALVES
3. DISCONNECT STOP VALVES FROM SERVICE VALVES ON REFRIGERANT LINE
4. INSTALL CAPS TO SERVICE VAL VES ON REFRIGERANT
LINE
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AIR CONDITIONING SYSTEM Use of Manifold Gauge SetAC±15
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RECOVERING OF REFRIGERANT IN
REFRIGERANT SYSTEM
When discharging refrigerant from the system as follows, use
a recovery machine to recover the refrigerant.Before replacing parts on the refrigerant line.
When moisture or air gets in the refrigerant line.
When excess refrigerant is charged.
NOTICE:
w When handling the recovery machine, always follow
the directions given in instruction manual.
w After recovery, the amount of compr essor oil
removed must be measured and same am ount
added into the system.
1. INSTALL MANIFOLD GAUGE SET TO SERVICE VALVES See page AC±15
2. RECOVER REFRIGERANT FROM REFRIGERATION
SYSTEM
(a) Connect the center hose to recovery machine.
(b) Operate the recovery machine.
(c) Open both high and low hand valves of manifold gauge set.
3. STOP RECOVERY MACHINE WHEN RECOVERING HAS FINISHED
4. REMOVE MANIFOLD GAUGE SET FROM SERVICE VA LV E S
See page AC±15
AC±16
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AIR CONDITIONING SYSTEM Recovering of Refrigerant in Refrigerant System
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EVACUATING AIR IN
REFRIGERATION SYSTEM AND
CHARGING WITH REFRIGERANT
HINT: Before charging the system with refrigerant, be sure
carry out a complete evacuation of the system.
1. INSTALL MANIFOLD GAUGE SET TO SERVICE VALVES See page AC±15
2. EVACUATE AIR IN REFRIGERATION SYSTEM (a) Connect the center hose of the manifold gauge set to the vacuum pump.
(b) Open both the high and low hand valves and run the vacuum pump.
HINT: If opening the low pressure hand valve pulls the high
pressure gauge into the vacuum range, there is no blokage
in the system.
(c) After ten minutes or more, check that the low pressure gauge indicates 99.99 kPa (750 mmHg, 29.53 in.Hg) or
more of vacuum.
HINT: If the reading is not 99.99 kPa (750 mmHg, 29.53
in.Hg) or more of vacuum, close both the high and low hand
valves of the manifold gauge set and stop vaccum pump.
Then, check the system for leaks and repair as necessary.
(d) Close both the high and low hand valves and stop the
vacuum pump.
(e) Leave the system in this condition for five minutes or longer and check that there is no change in the gauge
indicator.
3. INSTALL CHARGING CYLINDER NOTICE: When handling the charging cylinder, always
follow the directions given in the instruction manual.
(a) Charge the proper amount of refrigerant in charging cylinder.
(b) Connect the center hose to charging cylinder. NOTICE: Do not open both high and low hand valves of
manifold guage set.
(c) Press on the schrader valve on the side of manifold gauge and expel the air inside of the center hose.
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AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with RefrigerantAC±17
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4. INSPECT REFRIGERATION SYSTEM FOR LEAKSHINT: After evacuating the air in system, check the system for
leakage.
(a) Open the high pressure hand valve to charge the system with refrigerant.
(b) When the low pressure g auge indicates 98 kPa (1
kgf/cm, 14 psi), close the high pressure hand valve.
(c) Using a gas leak tester, check the system for leakage. If leak is found, repair the faulty component or connection.
5. CHARGE EMPTY REFRIGERATION SYSTEM WITH REFRIGERANT (LIQUID)
HINT: This step is used to charge an empty system through
the high pressure side with refrigerant in a liquid state.
NOTICE:
wNever run the engine when charging the system
through the high pressure side with refrigerant in a
liquid stae.
w Do not open the low pressure hand valve when the
system is being charged with liquid refrigerant.
(a) Open the high pressure hand valve fully.
(b) Charge the system with specified amount of refrigerant, then close the high pressure hand valve.
HINT:
w A fully charged system is indicated by the sight glass
being free of any bubbles.
w If the low pressure gauge does not show a reading, the
system is clogged and must be repaired.
AC±18
±
AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with Refrigerant
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6. CHARGE PARTIALLY REFRIGERATION SYSTEM WITHREFRIGERANT (VAPOR)
HINT: This step is used to charge the system through the low
pressure side with refrigerant in a vapor state.
NOTICE: Do not open the high pressure hand valve when
running the engine.
(a) Run the engine at ideling speed and operate the air
conditioner.
(b) Open the low pressure hand valve. NOTICE: Adjust the hand valve so that the low pressure
gauge does not indicate over limited pressure of charg-
ing cylinder.
(c) Close the low pressure hand valve when the sight glass is free of any bubbles and stop the engine.
NOTICE: Be careful not to overcharge the system with re-
frigerant as it may cause of troubles.
7. REMOVE MANIFOLD GAUGE SET FROM SERVICE VA LV E S
See page AC±15
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AIR CONDITIONING SYSTEM Evacuation Air in Refrigeration
System and Charging with RefrigerantAC±19
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