Lexus ES300 (2002 year). Manual - part 323

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DIAGNOSTICS

AIR CONDITIONING SYSTEM

05-469

622

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

No air outlet control

1. Air outlet damper position sensor circuit

2. Air outlet control servomotor circuit

3. Heater control housing sub-assy (A/C amplifier)

05-512

05-498

01-31

Engine idle up does not occur, or is continuous

1. Compressor circuit

2. Heater control housing sub-assy (A/C amplifier)

05-536

01-31

Set temperature value displayed does not much up with operation
of temperature control switch.

1. Heater control housing sub-assy (A/C amplifier)

01-31

Brightness does not changes when rheostat volume or light con-
trol switch it turned.

1. Illumination light system

2. Heater control housing sub-assy (A/C amplifier)

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01-31

Unable to access the diagnosis mode.

1. Heater control housing sub-assy (A/C amplifier)

01-31

DTC not recorded. Set mode is cleared when IG switch is turned
off.

1. Back-up power source circuit

2. Heater control housing sub-assy (A/C amplifier)

05-528

01-31

Seat heater does not operate.

1. Seat heater circuit

(Driver side)

(Passenger side)

2. Heater control housing sub-assy (A/C amplifier)

05-520

05-523

01-31

I18376

Heater Control Housing Sub-assy
(A/C Amplifier)

SG-5

TR

A15

A15

38

24

LG-B

B

A17
Room Temp. Sensor

1

2

05-470

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DIAGNOSTICS

AIR CONDITIONING SYSTEM

623

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

DTC

11

ROOM TEMPERATURE SENSOR CIRCUIT

CIRCUIT DESCRIPTION

This sensor detects the temperature inside the cabin and sends the appropriate signals to the A/C amplifier.

DTC No.

Detection item

Trouble Area

11

Open or short in room temperature sensor circuit

Room temperature sensor

Harness or connector between room temperature sensor and
A/C amplifier

A/C amplifier

WIRING DIAGRAM

056CL-01

E58224

SG-5

TR

A15

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DIAGNOSTICS

AIR CONDITIONING SYSTEM

05-471

624

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

INSPECTION PROCEDURE

1

INSPECT HEATER CONTROL HOUSING SUB-ASSY(TR, SG-5)

(a)

Remove A/C amplifier with connectors still connected.

(b)

Turn ignition switch ON.

(c)

Measure voltage between terminals TR and SG-5 of A/C
amplifier connector at each temperature.
Voltage: 
at 25  



C (77 



F) : 1.8 - 2.2 V

at 40 



C (104 



F) : 1.2 - 1.6 V

HINT:
As the temperature increases, the voltage decreases.

A

NG

B

OK
(when checking from the PROBLEM SYMPTOM TABLE)

C

OK (Checking from the DTC)

B

PROCEED TO NEXT CIRCUIT INSPECTION
SHOWN ON PROBLEM SYMPTOM TABLE

C

CHECK AND REPLACE HEATER CONTROL
HOUSING SUB-ASSY

A

I30111

I30156

Resistance (k

Ω

)

Temperature (



C)

05-472

-

DIAGNOSTICS

AIR CONDITIONING SYSTEM

625

2002 LEXUS ES300 REPAIR MANUAL   (RM911U)

2

INSPECT COOLER (ROOM TEMP. SENSOR) THERMISTOR

(a)

Remove cooler (room tem. sensor) thermistor.

(b)

Measure resistance between terminals 1 and 2 of cooler
(room temp. sensor) connector at each temperature.
Resistance: 1700 

85 

Ω

HINT:
As the temperature increases, the resistance decreases.

NG

REPLACE COOLER (ROOM TEMP. SENSOR)
THERMISTOR

OK

3

CHECK HARNESS AND CONNECTOR(BETWEEN COOLER (ROOM TEMP.
SENSOR) THERMISTOR AND HEATER CONTROL HOUSING)

NG

REPAIR OR REPLACE HARNESS OR
CONNECTOR

OK

CHECK AND REPLACE HEATER  CONTROL  HOUSING  SUB-ASSY