Lexus ES300 (1997 year). Manual - part 443

Weak

Strong

High

Low

Strength of solar radiation

Resistance o

f 

photodiode

I00323

A/C Control Assembly

5 V

S5

TS

A13

L

11

5

A14

J19

J18

C

A

J/C

IG1

9

W

IG1

8

W

L

Solar Sensor

L

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–549

701

1997 LEXUS ES300   (RM511U)

DTC

   21

Solar Sensor Circuit

CIRCUIT DESCRIPTION

A photo diode in the solar sensor detects solar radiation and
sends signals to the A/C control assembly.

DTC No.

Detection Item

Trouble Area

21

Open or short in solar sensor circuit.

(Please note that display of DTC 21 is not abnormal when the

sensor is not receiving solar radiation.)

Solar sensor

Harness or connector between solar sensor and A/C control

assembly

A/C control assembly

WIRING DIAGRAM

DI0DC–01

BE3840

I00324

I00336

ON

S5(–)

TS(+)

DI–550

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

702

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

1

Check voltage between terminals S5 and TS 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 S5 and TS of A/C control
assembly connector when the solar sensor is subjected to an
electric light, and when the sensor is covered by a cloth.
OK:

Condition

Voltage

Sensor subjected to electric light

Below 4.0 V

Sensor covered by a cloth

4.0 – 4.5 V

HINT:
As the inspection light is gradually moved away from the sen-
sor, the voltage increases.

NG

Go to step 2

NG

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

DI–535

). However, if DTC 21

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

I00325

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–551

703

1997 LEXUS ES300   (RM511U)

2

Check solar sensor.

PREPARATION:
(a)

Remove instrument panel (See page 

BO–79

).

(b)

Disconnect solar sensor connector.

CHECK:
(a)

Cover the sensor by a cloth.

(b)

Measure resistance between terminals 1 and 2 of solar
sensor connector.

HINT:
Connect positive (+) lead of ohmmeter to terminal 2 and nega-
tive (–) lead to terminal 1 of the solar sensor.
OK:

Resistance: 

∞Ω

(No continuity)

PREPARATION:
Remove the cloth from the solar sensor and subject the sensor
to electric light.
CHECK:
Measure resistance.
OK:

Resistance: Below 10 k

Ω

 (Continuity)

HINT:
As the electric light is moved gradually away from the sensor,
the resistance increases.

NG

Replace solar sensor.

OK

3

Check harness and connector between A/C control assembly and solar sensor
(See page 

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace A/C control assembly.

I00326

A/C Control Assembly

LOCK

SG

A/C Compressor
Lock Sensor

W–L

W–L

W–R

3

1

A13

J20

J20

E

E

J/C

IM2

10

IM2

9

A13

W–R

W–R

DI–552

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

704

1997 LEXUS ES300   (RM511U)

DTC

   22

Compressor Lock Sensor Circuit

CIRCUIT DESCRIPTION

This sensor sends 4 pulses par engine revolution to the A/C control assembly. If the number ratio of the com-
pressor speed divided by the engine speed is smaller than a predetermined value, the A/C control assembly
turns the compressor off. And, the indicator flashes at about 1 second intervals.

DTC No.

Detection Item

Trouble Area

22

All conditions below are detected for 3 secs. or more.

(a) Engine speed: 450 rpm or more

(b) Ratio between engine and compressor speed deviates

      20 % or more in comparison to normal operation.

Compressor

Compressor drive belt

Compressor lock sensor

Harness and connector between compressor and A/C control

assembly

A/C control assembly

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check compressor.

PREPARATION:
(a)

Check compressor drive belt tension (See page 

AC–14

).

(b)

Check if the compressor does not lock during operation with engine started and blower switch and A/C
switch ON.

NG

Adjust drive belt tension or repair compressor.

OK

DI0DD–01