2000 LEXUS GS400 Service Repair Manual

I01387
Condition : Periodically cools and then fails to cool
I01388
Condition: Insufficient cooling
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±5
2690 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(2) Moisture present in refrigeration system.
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy
During operation, pressure on low
pressure side sometimes become
a vacuum and sometime normal
Moisture entered in refrigeration
system freezes at expansion valve
orifice and temporarily stops cycle,
but normal state is restored after a
time when the ice melts
Dryer in oversaturated state

Moisture in refrigeration system
freezes at expansion valve orifice
and blocks circulation of refriger-
ant(1) Replace dryer
(2) Remove moisture in cycle
through repeatedly evacuating air
(3) Charge proper amount of new
refrigerant
(3) Insufficient cooling
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure low on both low and
high pressure sides

Bubbles seen in sight glass con-
tinuously

Insufficient cooling performance
Gas leakage at some place in re-
frigeration system
Insufficient refrigerant in system

Refrigerant leaking
(1) Check for gas leakage with gas
leak detector and repair if neces-
sary
(2) Charge proper amount of re-
frigerant
(3) If indicated pressure value is
near 0 when connected to gauge,
create the vacuum after inspecting
and repairing the location of the
leak

I01389
Condition: Insufficient cooling
I01449
Condition: Does not cool (Cools from time to time in some cases) AC±6
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
2691 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(4) Poor circulation of refrigerant
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure low in both low and
high pressure sides

Frost on tube from condenser to
unit
Refrigerant flow obstructed by dirt
in condensercondenser cloggedReplace condenser
(5) Refrigerant does not circulate
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Vacuum indicated on low pres-
sure side, very low pressure indi-
cated on high pressure side

Frost or dew seen on piping be-
fore and after condenser/ dryer or
expansion valve
Refrigerant flow obstructed by
moisture or dirt in refrigeration sys-
tem

Refrigerant flow obstructed by
gas leakage from expansion valve
Refrigerant does not circulate
(1) Check expansion valve
(2) Clean out dirt in expansion
valve by blowing with air
(3) Replace condenser
(4) Evacuate air and charge new
refrigerant to proper amount
(5) For gas leakage from expan-
sion valve, replace expansion
valve

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

I01450
Condition: Insufficient cooling
I01393
Condition : Does not cool AC±8
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
2693 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(8) Expansion valve improperly
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure too high on both low
and high pressure sides

Frost or large amount of dew on
piping on low pressure side
Trouble in expansion valve

Excessive refrigerant in low
pressure piping

Expansion valve opened too
wide
Check expansion valve
Replace if defective
(9) Defective compression compressor
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure too high on low and
high pressure sides

Pressure too low on high pres-
sure side
Internal leak in compressor

Compression defective

Valve leaking or broken sliding
parts
Repair or replace compressor

± 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.

AC0WP±01
I02367
I02368
I02369
AC±30
± AIR CONDITIONINGBLOWER UNIT
2715 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REMOVAL
1. REMOVE INSTRUMENT PANEL AND REINFORCE-
MENT
(See page BO±91)
2. REMOVE AIR DUCT
(a) Disconnect the connector clamp.
(b) Remove the 3 screws and air duct.
3. DISCONNECT WIRE HARNESS
(a) Release the claw of the connector bracket and discon-
nect the connector bracket.
(b) Disconnect the wire harness set clamps.
(c) Disconnect the wire harness.
4. REMOVE BLOWER UNIT
(a) Disconnect the connectors.
(b) Remove the 2 bolts and bracket.
(c) Remove the bolt, screw and nut.
(d) Remove the blower unit.

AC0WQ±01
± AIR CONDITIONINGBLOWER UNIT
AC±31
2716 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
DISASSEMBLY
1. REMOVE AIR REFINER FILTER
(a) Release the 4 claws and remove the cover.
(b) Pull out the air refiner filter.
2. REMOVE AIR INLET SERVOMOTOR
Remove the 3 screws and servomotor.
3. REMOVE BLOWER MOTOR
Remove the 3 screws and blower motor.
4. REMOVE BRACKET
Remove the screw and bracket.

AC0WR±01
AC±32
± AIR CONDITIONINGBLOWER UNIT
2717 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REASSEMBLY
Reassembly is in the reverse order of disassembly (See page AC±26).