Lexus ES300 (1997 year). Manual — part 441

BE3840

I00319

I00334

ON

SG(–)

TAM(+)

I00320

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–541

693

1997 LEXUS ES300 (RM511U)

INSPECTION PROCEDURE

1

Check voltage between terminals TAM and SG of air conditioning control assem-
bly connector.

PREPARATION:
(a)

Remove the A/C control assembly with connectors still
connected (See page

BO–79

).

(b)

Turn ignition switch ON.

CHECK:
Check voltage between terminals TAM and SG of A/C control
assembly connector at each temperature.
OK:

Voltage
at 25

°

C (77

°

F): 1.35 – 1.75 V

at 40

°

C (104

°F): 0.85 − 1.25 V

HINT:
As the temperature increases, the voltage decreases.

NG

Go to step 2.

OK

Proceed to the next circuit inspection shown on matrix chart (See page

DI–535

). However, if DTC

12 is displayed, check and replace A/C control assembly.

2

Check ambient temperature sensor.

PREPARATION:
Disconnect ambient temperature sensor connector.
CHECK:
Check resistance between terminals 1 and 2 of ambient tem-
perature sensor connector at each temperature.
OK:

Resistance
at 25

°

C (77

°

F): 1.6 – 1.8 k

Ω

at 40

°

C (104

°F): 0.5 − 0.7k

Ω

NG

Replace ambient temperature sensor.

OK

DI–542

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

694

1997 LEXUS ES300 (RM511U)

3

Check harness and connector between A/C control assembly and ambient tem-
perature sensor (See page

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace A/C control assembly.

I00321

A/C Control Assembly

5 V

TE

6

A14

1

A13

SG

L–W

Evaporator Temp.
Sensor

2

1

W–R

W–R

J20

J20

E

E

J/C

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–543

695

1997 LEXUS ES300 (RM511U)

DTC

13

Evaporator Temperature Sensor Circuit

CIRCUIT DESCRIPTION

This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the A/C
control assembly.

DTC No.

Detection Item

Trouble Area

13

Open or short in evaporator temperature sensor circuit.

Evaporator temperature sensor.

Harness or connector between evaporator temperature sen-

sor and A/C control assembly.

A/C control assembly.

WIRING DIAGRAM

DI0DA–01

I00322

BE3840

I00335

ON

SG(–)

TE(+)

AC0175

Thermometer

Ice

Ohmmeter

Thermistor

More

than

10 cm

(3.94 in.)

DI–544

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

696

1997 LEXUS ES300 (RM511U)

INSPECTION PROCEDURE

1

Check voltage between terminals TE and SG of A/C control assembly connector.

PREPARATION:
(a)

Remove A/C control assembly with connectors still con-
nected (See page

BO–79

).

(b)

Turn ignition switch ON.

CHECK:
Measure voltage between terminals TE and SG of A/C control
assembly connector at each temperature.
OK:

Voltage
at 0

°

C (32

°

F): 2.0 – 2.4 V

at 15

°

C (59

°

F): 1.4 – 1.8 V

HINT:
As the temperature increases, the voltage decreases.

NG

Go to step 2

OK

Proceed to next circuit inspection shown on matrix chart (See page

DI–535

). However, if DTC 13

is displayed, check and replace A/C control assembly.

2

Check evaporator temperature sensor.

PREPARATION:
Remove evaporator temperature sensor (See page

AC–88

).

CHECK:
Check resistance between terminals 1 and 2 of evaporator tem-
perature sensor connector at each temperature.
OK:

Resistance
at 0

°

C (32

°

F): 4.6 – 5.1 k

Ω

at 15

°

C (59

°

F): 2.1 – 2.6 k

Ω

HINT:
As the temperature increases, the voltage decreases.

NG

Replace evaporator temperature sensor.

OK