2003 LEXUS LS430 air condition

1.PERFORM ACTUATOR CHECK
a. Warm up the engine.
b. Set the actuator check mode (SEE ACTUATOR CHECK
).
c. Press the driver temperature up switch, and change to STEP operation.
d. Press the driver temperature up switch, and check the air flow by hand.
DISPLAY CODE - AIR FLOW POSITION
OK:
Cool air bypass damper changes in accordance with each display code.
NG: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
OK: Go to next step
2.INSPECT COOL AIR BYPASS SERVOMOTOR
a. Remove the cool air bypass servomotor.
b. Connect the positive (+) lead from the battery to terminal 4 and negative (-) lead to terminal 5, then
check that the lever turns to the "OPEN" position smoothly.
c. Connect the positive (+) lead from the battery to terminal 5 and negative (-) lead to terminal 4, then
check that the lever turns to the "SHUT" position smoothl
y.
Display codeAir flow position
0OPEN
1OPEN
2OPEN
3SHUT
4SHUT
5SHUT
6SHUT
7SHUT
8SHUT
9SHUT

Fig. 127: Inspecting Cool Air Bypass Servomotor
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE COOL AIR BYPASS SERVOMOTOR
OK: Go to next step
3.CHECK HARNESS AND CONNECTOR (COOL AIR BYPASS SERVOMOTOR - AIR
CONDITIONING AMPLIFIER) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
COOL AIR BYPASS SERVOMOTOR - AIR CONDITIONING AMPLIFIER RESISTANCE
Tester connectionConditionSpecified condition
A37-16 (ABODr) - C24-4 (MOPEN)AlwaysBelow 1 ohms
A37-17 (ABSDr) - C24-5 (MSNUT)AlwaysBelow 1 ohms
A36-11 (S5-5) - C24-1 (VZ)AlwaysBelow 1 ohms
A36-15 (SG-7) - C24-2 (GND)AlwaysBelow 1 ohms
C24-4 (MOPEN) - Body groundAlways10 kohms or higher
C24-5 (MSNUT) - Body groundAlways10 kohms or higher

Fig. 128: Checking Harness And Connector (Cool Air Bypass Servomotor - Air Conditioning

Amplifier)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
The cool air bypass servomotor is controlled by the A/C amplifier and moves the cool air bypass damper to the
desired position.
WIRING DIAGRAM

Fig. 129: Cool Air Bypass Damper Control Servomotor Circuit (Passenger Side)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.PERFORM ACTUATOR CHECK

a. Warm up the engine.
b. Set the actuator check mode (SEE ACTUATOR CHECK
).
c. Press the driver temperature up switch, and change to STEP operation.
d. Press the driver temperature up switch, and check the air flow by hand.
Display code Air flow position
DISPLAY CODE AIR FLOW POSITION
OK:
Cool air bypass damper changes in accordance with each display code.
NG: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
OK: Go to next step
2.INSPECT COOL AIR BYPASS SERVOMOTOR
a. Remove the cool air bypass servomotor.
b. Connect the positive (+) lead from the battery to terminal 4 and negative (-) lead to terminal 5, then
check that the lever turns to the "OPEN" position smoothly.
c. Connect the positive (+) lead from the battery to terminal 5 and negative (-) lead to terminal 4, then
check that the lever turns to the "SHUT" position smoothly.
Display codeAir flow lever position
0OPEN
1OPEN
2OPEN
3SHUT
4SHUT
5SHUT
6SHUT
7SHUT
8SHUT
9SHUT

Fig. 130: Inspecting Cool Air Bypass Servomotor
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPLACE COOL AIR BYPASS SERVOMOTOR
OK: Go to next step
3.CHECK HARNESS AND CONNECTOR (COOL AIR BYPASS SERVOMOTOR - AIR
CONDITIONING AMPLIFIER) (SEE ELECTRONIC CIRCUIT INSPECTION PROCEDURE
)
a. Measure the resistance according to the value (s) in the table below.
Standard:
COOL AIR BYPASS SERVOMOTOR - AIR CONDITIONING AMPLIFIER RESISTANCE
Tester connectionConditionSpecified condition
A37-8 (ABOPa) - C25-4 (MOPEN)AlwaysBelow 1 ohms
A37-9 (ABSPa) - C25-5 (MSNUT)AlwaysBelow 1 ohms
A37-18 (S5-3) - C25-1 (VZ)AlwaysBelow 1 ohms
A37-19 (SG) - C25-2 (GND)AlwaysBelow 1 ohms
C25-4 (MOPEN) - Body groundAlways10 kohms or higher

Fig. 131: Checking Harness And Connector (Cool Air Bypass Servomotor - Air Conditioning

Amplifier)
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE AIR CONDITIONING AMPLIFIER (SEE REPLACEMENT
)
CIRCUIT DESCRIPTION
This circuit controls the amount of the coolant flowing to the heater core by a signal from the A/C amplifier,
and adjusts the temperature at the air outlets.
WIRING DIAGRAM
Fig. 132: Water Valve Control Servomotor Circuit

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.