2000 LEXUS GS400 engine

AC2810
AC0W6±01
AC2811
N11084
Wrong Okay
HI LO HILO
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±1
2686 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
AIR CONDITIONING SYSTEM
PRECAUTION
1. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED
AREA OR NEAR AN OPEN FLAME
2. ALWAYS WEAR EYE PROTECTION
3. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN
YOUR EYES OR ON YOUR SKIN
If liquid refrigerant gets in your eyes or on your skin.
(a) Wash the area with lots of cool water.
CAUTION:
Do not rub your eyes or skin.
(b) Apply clean petroleum jelly to the skin.
(c) Go immediately to a physician or hospital for professional
treatment.
4. NEVER HEAT CONTAINER OR EXPOSE IT TO NAKED
FLAME
5. BE CAREFUL NOT TO DROP CONTAINER AND NOT
TO APPLY PHYSICAL SHOCKS TO IT
6. DO NOT OPERATE COMPRESSOR WITHOUT
ENOUGH REFRIGERANT IN REFRIGERANT SYSTEM
If there is not enough refrigerant in the refrigerant system oil lu-
brication will be insufficient and compressor burnout may occur,
so take care to avoid this, necessary care should be taken.
7. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE
WHILE COMPRESSOR IS OPERATING
If the high pressure valves opened, refrigerant flows in the re-
verse direction and could cause the charging cylinder to rup-
ture, so open and close the only low pressure valve.
8. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as insuffi-
cient cooling, poor fuel economy, engine overheating etc.

AC0WA±01
I03811
Smog Ventilation
Sensor
No. 2 Cooling Fan Relay
(Marking: FAN NO.2) No. 3 Cooling Fan Relay
(Marking: FAN NO.3)
CompressorMagnetic Clutch Relay
(Marking A/C COMP)
Condenser
Ambient Temperature Sensor Condenser Fan
Engine Coolant Temperature
(ECT) Switch
Air Inlet Servomotor
Blower Motor
Air Outlet Servomotor A/C Amplifier
EvaporatorSolar Sensor A/C Control Assembly
Electrical Multi Vision
(Built in A/C Control Assembly)
Expansion Valve
Air Refiner Filter
Blower Motor Control
Relay Evaporator Temperature
Sensor
Heater Radiator
Air Mix Servomotor
(Driver Side) Air Mix Servomotor
(Passenger Side)Room Temperature
Sensor
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±13
2698 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
LOCATION

AC0WK±01
I02360
I02361
AC±24
± AIR CONDITIONINGAIR CONDITIONING UNIT
2709 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REMOVAL
1. DISCHARGE REFRIGERANT FROM REFRIGERATION
SYSTEM
HINT:
At the time of installation, please refer to the following item.
Evacuate air from refrigeration system.
Charge system with refrigerant and inspect for leakage of refrig-
erant.
Specified amount: 600 ± 50 g (21.16 ± 1.76 oz.)
2. DRAIN ENGINE COOLANT FROM RADIATOR
HINT:
It is not necessary to drain out all coolant.
3. DISCONNECT LIQUID TUBE AND SUCTION HOSE
FROM A/C UNIT
Remove the bolt and slide the plate, then disconnect the both
tubes.
Torque: 10 N´m (100 kgf´cm, 7 ft´lbf)
NOTICE:
Cap the open fittings immediately to keep moisture or dirt
out of the system.
HINT:
At the time of installation, please refer to the following item.
Lubricate 2 new O±rings with compressor oil and install them
to the tubes.
4. DISCONNECT WATER HOSES FROM HEATER RA-
DIATOR PIPES
(a) Grips the claws of the hose clip and slide the hose clip
along the hose.
(b) Disconnect the water hose.

AC0W7±02
I02352
Sight Glass
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±3
2688 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ON±VEHICLE INSPECTION
1. INSPECT REFRIGERANT VOLUME
Observe the sight glass on the liquid tube.
Test conditions:

Running engine at 1,500 rpm

Blower speed control switch at ºHIº position

A/C switch ON

Temperature control dial at ºCOOLº position

Fully open the doors
ItemSymptomAmount of refrigerantRemedy
1Bubbles present in sight glassInsufficient*
(1) Check for gas leakage with gas leak de-
tector and repair if necessary
(2) Add refrigerant until bubbles disappear
2No bubbles present in sight glassNone, sufficient or too muchRefer item 3 and 4
3No temperature difference between com-
pressor inlet and outletEmpty or nearly empty
(1) Check for gas leakage with gas leak de-
tector and repair if necessary
(2) Add refrigerant until bubbles disappear
4Temperature between compressor inlet and
outlet is noticeably differentCorrect or too muchRefer to items 5 and 6
5Immediately after air conditioning is turned
off, refrigerant in sight glass stays clearToo much
(1) Discharge refrigerant
(2) Evacuate air and charge proper amount
of purified refrigerant
6When air conditioning is turned off, refriger-
ant foams and then stays clearCorrect±
*: Bubbles in the sight glass with ambient temperatures higher than usual can be considered normal if cooling
is sufficient.

I01386
AC±4
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
2689 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
2. INSPECT REFRIGERANT PRESSURE WITH MAN-
IFOLD GAUGE SET
This is a method in which the trouble is located by using a man-
ifold gauge set. Read the manifold gauge pressure when these
conditions are established.
Test conditions:

Temperature at the air inlet with the switch set
at RECIRC is 30 ± 35 °C (86 ± 95 °F)

Engine running at 2,000 rpm

Blower speed control switch at ºHIº position

Temperature control dial on ºCOOLº position
HINT:
It should be noted that the gauge indications may vary slightly
due to ambient temperature conditions.
(1) Normally functioning refrigeration system.
Gauge reading:
Low pressure side:
0.15 ± 0.25 MPa (1.5 ± 2.5 kgf/cm
2)
High pressure side:
1.37 ± 1.57 MPa (14 ± 15 kgf/cm
2)

I01390
Condition: Insufficient cooling
I01392
Condition: Insufficient cooling
NOTE : These gauge indica-
tions are shown when the
refrigeration system has
been opened and the refrig-
erant charged without vacu-
um purging.
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±7
2692 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(6) Refrigerant overcharged or insufficient cooling of
condenser
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure too high on both low
and high pressure sides

No air bubbles seen through the
sight glass even when the engine
rpm is lowered
Unable to develop sufficient per-
formance due to excessive refrig-
eration system

Insufficient cooling of condenser
Excessive refrigerant in
cycle " refrigerant over charged

Condenser cooling " condenser
fins clogged of condenser fan
faulty
(1) Clean condenser
(2) Check condenser fan motor
operation
(3) If (1) and (2) are in normal
state, check amount of refrigerant
Charge proper amount of refriger-
ant
(7) Air present in refrigeration system
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure too high on both low
and high pressure sides

The low pressure piping hot to
touch

Bubbles seen in sight glass
Air entered in refrigeration system

Air present in refrigeration sys-
tem

Insufficient vacuum purging
(1) Check compressor oil to see if
it is dirty or insufficient
(2) Evacuate air and charge new
refrigerant

± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±9
2694 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. INSPECT IDLE±UP SPEED
(a) Warm up engine
(b) Inspect idle±up speed when the these conditions are es-
tablished.
Test conditions:

Blower speed control switch at ºHIº position

Temperature control dial at ºCOOLº position

A/C switch ON

Put gear shift in neutral
GS300:
Magnetic clutch conditionIdle±up speed
Magnetic clutch not engaged700 ± 50 rpm
Magnetic clutch engaged800 ± 50 rpm
If idle speed is not as specified, check the idle control system.
GS400:
Magnetic clutch conditionIdle±up speed
Magnetic clutch not engaged750 ± 50 rpm
Magnetic clutch engaged800 ± 50 rpm
If idle speed is not as specified, check the idle control system.
4. INSPECT FOR LEAKAGE OF REFRIGERANT
(a) Perform in these conditions.

Stop engine

Secure good ventilation (If the gas leak detector
may not react volatile gases which are not refriger-
ant, such as evaporated gasoline and exhaust gas)

Repeat the test 2 or 3 times

Make sure that there is some refrigerant remaining
in the refrigeration system.
When compressor is OFF: approx. 392 ± 588 kPa
(4 ± 6 kgf´cm
2, 57 ± 85 psi)
(b) Bring the gas leak detector close to the drain hose before
performing the test.
HINT:

After the blower motor has stopped, leave the cooling for
more than 15 minutes.

Expose the gas leak detector sensor under the drain
hose.

When bring the gas leak detector close to the drain hose,
make sure that the gas leak detector does not react to the
volatile gases.
If such reaction is unavoidable, the vehicle must be lifted up.
(c) If gas leak is not detected on the drain hose, remove the
blower resistor from the cooling unit. Then insert the gas
leak detector sensor into the unit and perform the test.
(d) Disconnect the connector and leave the pressure switch
for approx. 20 minutes. Then bring the gas leak detector
close to the pressure switch and perform the test.
(e) Bring the gas leak detector close to the refrigerant lines.

I02376
GS300:
3
I02375
GS400:
3
± AIR CONDITIONINGCOMPRESSOR AND MAGNETIC CLUTCH
AC±35
2720 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
5. MAKE THESE VISUAL CHECKS:
(a) Leakage of grease from the clutch bearing.
(b) Signs of oil on the pressure plate or rotor.
6. INSPECT MAGNETIC CLUTCH BEARING FOR NOISE
(a) Start engine.
(b) Check for abnormal noise from the compressor when the
A/C switch is OFF.
If abnormal noise is being emitted, replace the rotor of magnetic
clutch.
7. INSPECT MAGNETIC CLUTCH OPERATION
(a) Disconnect the connector.
(b) Connect the positive (+) lead from the battery to terminal
3 and the negative (±) lead to the body ground.
(c) Check that the magnetic clutch is energized.
If operation is not as specified, replace the magnetic clutch.