2000 LEXUS GS400 Service Repair Manual

I03739
I03737
I03738
I03740
± AIR CONDITIONINGSENSOR
AC±73
2758 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. REMOVE AMBIENT TEMPERATURE SENSOR
(a) Disconnect the connector.
(b) Using a clip remover, pull out the sensor from bumper re-
inforcement.
4. REMOVE EVAPORATOR TEMPERATURE SENSOR
(a) Remove these parts:
(1) No.1 under cover
(2) No.1 safety pad
(See page BO±91)
(b) Remove the evaporator temperature sensor.
(1) Using a screwdriver, pull out the sensor with bracket
plate.
HINT:
Tape the screwdriver tip before use.
(2) Release the 2 claws and remove the sensor from
bracket plate.
5. REMOVE SMOG VENTILATION SENSOR
(a) Disconnect the connector.
(b) Remove the bolt and sensor.

AC0XL±01
AC±74
± AIR CONDITIONINGSENSOR
2759 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. INSPECT SOLAR SENSOR CIRCUIT
Driver Side: (See page DI±1093)
Passnger Side: (See page DI±1084)
2. INSPECT ROOM TEMPERATURE SENSOR CIRCUIT
(See page DI±1071)
3. INSPECT AMBIENT TEMPERATURE SENSOR CIRCUIT
(See page DI±1074)
4. INSPECT EVAPORATOR TEMPERATURE SENSOR
(See page DI±1078)
5. INSPECT SMOG VENTILATION SENSOR CIRCUIT
(See page DI±1093)

AC0XM±01
± AIR CONDITIONINGSENSOR
AC±75
2760 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSTALLATION
Installation is in the reverse order of removal (See page AC±72).

I03741
2 1
3
4
AC0XN±01
Z13470
Magnetic Clutch Control
Low Pressure Side
ON (Continuity)
181 kpa
(1.85 kgf´cm
2, 28 psi)
OFF (No Continuity)High Pressure Side
3,140 kpa
(32.0 kgf´cm2, 455 psi)
OFF (No Continuity)
Z13471
Cooling Fan Control
ON1,520 kpa
(15.5 kgf´cm
2, 220 psi)
(No Continuity) (Continuity)
OFF
1,230 kpa
(12.5 kgf´cm
2, 178 psi) AC±76
± AIR CONDITIONINGPRESSURE SWITCH
2761 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
PRESSURE SWITCH
ON±VEHICLE INSPECTION
1. SET ON MANIFOLD GAUGE SET
(See page AC±17)
2. DISCONNECT CONNECTOR FROM PRESSURE
SWITCH
3. RUN ENGINE AT APPROX. 1,500 RPM
4. Magnetic Clutch Control:
INSPECT PRESSURE SWITCH OPERATION
(a) Connect the positive (+) lead from the ohmmeter to termi-
nal 4 and the negative (±) lead to terminal 1.
(b) Check continuity between terminals when refrigerant
pressure is changed, as shown in the illustration.
If operation is not as specified, replace the pressure switch.
5. Cooling Fan Control:
INSPECT PRESSURE SWITCH OPERATION
(a) Connect the positive (+) lead from the ohmmeter to termi-
nal 2 and the negative (±) lead to terminal 3.
(b) Check continuity between terminals when refrigerant
pressure is changed, as shown in the illustration.
If operation is not as specified, replace the pressure switch.
6. STOP ENGINE AND SET OFF MANIFOLD GAUGE SET
7. CONNECT CONNECTOR TO PRESSURE SWITCH

AC0XO±01
I03742
± AIR CONDITIONINGPRESSURE SWITCH
AC±77
2762 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. REMOVE PRESSURE SWITCH FROM LIQUID TUBE
Disconnect the connector and remove the pressure switch.
Torque: 10 N´m (100 kgf´cm, 7 ft´lbf)
HINT:

Lock the switch mount on the tube with an open end
wrench, being careful not to deform the tube, and remove
the switch.

At the time of installation, please refer to the following
item.
Lubricate a new O±ring with compressor oil and install the
switch.

AC0XP±01
AC±78
± AIR CONDITIONINGPRESSURE SWITCH
2763 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSTALLATION
Installtion is in the reverse order of removal (See page AC±77).

Z19533
32 1
541
43 2
5AC0XQ±01
I050271 2
5
1235
3
N23635
3
2
15
4
± AIR CONDITIONINGRELAY
AC±79
2764 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
RELAY
INSPECTION
1. INSPECT HEATER MAIN RELAY
(Marking: HTR) CONTINUITY
ConditionTester connectionSpecified condition
Constant2 ± 4
1 ± 3Continuity
Apply B+ between
terminals 1 and 3.5 ± 4Continuity
If continuity is not as specified, replace the relay.
2. INSPECT MAGNETIC CLUTCH RELAY
(Marking: A/C COMP) CONTINUITY
ConditionTester connectionSpecified condition
Constant1 ± 2Continuity
Apply B+ between
terminals 1 and 2.3 ± 5Continuity
If continuity is not as specified, replace the relay.
3. INSPECT No.2 COOLING FAN RELAY
(Marking: FAN NO.2) CONTINUITY
ConditionTester connectionSpecified condition
Constant1 ± 2
3 ± 4Continuity
Apply B+ between
terminals 1 and 2.3 ± 5Continuity
If continuity is not as specified, replace the relay.
4. INSPECT No.3 COOLING FAN RELAY
(Marking: FAN NO.3) CONTINUITY
Check the relay in the same way as for ºMAGNETIC CLUTCH
RELAYº.

AC0Y2±01
I03743
1 2 AC±80
± AIR CONDITIONINGCONDENSER FAN
2765 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
CONDENSER FAN
ON±VEHICLE INSPECTION
1. INSPECT CONDENSER FAN OPERATION
Inspect the fan operation, as shown in the chart below.
Test conditions:

Ignition switch ON

Blower speed control switch position ºHIº

Temperature control dial at ºMAX. COOLº

Install manifold gauge setº

A/C switch ON
ConditionFan operation (Fan speed)
Engine coolant temperature
91°C (196 °F) or belowRotate (Low speed)
Engine coolant temperature
100°C (212 °F) or aboveRotate (High speed)
Refrigerant pressure is less than
1,520 kPa (15.5 kgf´cm2, 220 psi)Rotate (Low speed)
Refrigerant pressure is 1,520 kPa
(15.5 kgf´cm2, 220 psi) or aboveRotate (High speed)
If operation is not as specified, proceed to the next inspection.
2. INSPECT CONDENSER FAN MOTOR OPERATION
(a) Disconnect the fan connector.
(b) Connect the positive (+) lead from the battery to terminal
2 and negative (±) lead to terminal 1 then check that motor
operations smoothly.

If operation is not as specified, replace the fan mo-
tor.

If operation is as specified, check the pressure
switch, cooling fan relays and engine coolant temp.
switch.