Lexus RX300 (MCU15). Manual - part 403

I18283

Hot

Cool

Hot

Cool

LHD model:

RHD model:

DI–842

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Actuator check.

PREPARATION:
(a)

Warm up the engine.

(b)

Set to the actuator check mode (See page DI–805).

(c)

Press the A/C switch and change it to step operation.

CHECK:
Press the A/C switch and check the operation of the air mix
damper and the condition of the blower.
OK:

Display Code

Air Mix Damper

Condition

0 – 3

4 – 5

6 – 9

0% (Fully closed)

50%

100% (Fully opened)

Cool air comes out

Warm air comes out

OK

Proceed to next circuit inspection shown on
problem symptoms table (See page DI–812).

NG

2

Check air mix damper control servomotor.

PREPARATION:
Remove air mix damper control servomotor
(See page AC–62).
CHECK:
Connect positive (+) lead to terminal 7 and negative (–) lead to
terminal 6.
OK:

The lever turns smoothly to Hot side.

CHECK:
Connect positive (+) lead to terminal 6 and negative (–) lead to
terminal 7.
OK:

The lever turns smoothly to Cool side.

NG

Replace air mix damper control servomotor as-
sembly.

OK

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–843

LEXUS RX300   (RM785E)

3

Check harness and connector between A/C ECU (Combination meter ECU) and
air mix damper control servomotor assembly (See page IN–32).

NG

Repair or replace harness or connector.

OK

Check and replace A/C ECU (Combination
meter ECU).

I05277

A/C ECU (Combina-
tion meter ECU)

AIF

R

13

6

BR–Y

A24 
Air Inlet Damper
Servomotor

7

12

AIR

C11

C11

DI–844

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

DTC

B1442/42 Air Inlet Damper Control Servomotor Circuit

CIRCUIT DESCRIPTION

The air inlet damper control servomotor is controlled by the A/C ECU (Combination meter ECU) and moves
the air inlet damper to the desired position.

DTC No.

Detection item

Trouble Area

Air inlet damper position sensor value does not change even if

S Air inlet damper position sensor.

B1442/42

Air inlet damper position sensor value does not change even if

A/C ECU (Combination meter ECU) operated air inlet damper

S Harness or connector between air inlet damper control servo-

motor assembly and A/C ECU (Combination meter ECU)

(

)

control servomotor.

motor assembly and A/C ECU (Combination meter ECU).

S A/C ECU (Combination meter ECU).

WIRING DIAGRAM

DI3G4–02

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–845

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Actuator check.

PREPARATION:
(a)

Remove glove box to see and check the air inlet damper
operation.

(b)

Set to the actuator check mode (See page DI–805).

(c)

Press the A/C switch and change it to step operation.

CHECK:
Press the A/C switch in order and check the operation of air inlet
damper.
OK:

Display Code

Air Inlet Damper

0 – 1

FRS

2

F/R

3 – 5

REC

6 – 9

FRS

OK

Proceed to next circuit inspection shown on
problem symptoms table (See page DI–812).

NG