Lexus RX300 (MCU15). Service manual - part 404

I18284

LHD model:

RHD model:

REC

FRS

FRS

REC

DI–846

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

2

Check air inlet damper control servomotor.

PREPARATION:
(a)

Remove blower unit (See page AC–38).

(b)

Disconnect the air inlet damper control servomotor as-
sembly connector.

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

The lever moves smoothly to REC position.

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

The lever moves smoothly to FRS position.

NG

Replace air inlet damper control servomotor as-
sembly.

OK

3

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

NG

Repair or replace harness or connector.

OK

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

I05279

A/C ECU (Combina-
tion meter ECU)

6

LG–B

7

10

A26 
Air Outlet Damper
Control Servomotor

W

IF1

C10

1

R–W

6

5

AOF

AOD

IF1

LG–B

C10

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–847

LEXUS RX300   (RM785E)

DTC

B1443/43 Air Outlet Damper Control Servomotor Cir-

cuit

CIRCUIT DESCRIPTION

This circuit turns the servomotor and changes each mode damper position by the signals from the A/C ECU
(Combination meter ECU).  When the AUTO switch is on, the A/C ECU (Combination meter ECU) changes
the mode automatically between (FACE), (BI–LEVEL) and (FOOT) according to the temperature setting.

DTC No.

Detection Item

Trouble Area

S Air outlet damper control servomotor.

S Air outlet damper position sensor

B1443/43

Air outlet damper position sensor value does not change even

if A/C ECU (C

bi

ti

t

ECU)

t d i

tl t

S Air outlet damper position sensor.

S Harness or connector between air outlet damper control ser-

t

d A/C ECU (C

bi

ti

t

ECU)

B1443/43

if A/C ECU (Combination meter ECU) operated air outlet

damper control servomotor.

vomotor and A/C ECU (Combination meter ECU)

S Harness or connector between air outlet damper position

sensor and A/C ECU (Combination meter ECU)

S A/C ECU (Combination meter ECU).

WIRING DIAGRAM

DI3G5–02

Display Code

Air Flow

0 ∼ 4

5

6, 7

8

9

FACE

BI–LEVEL

FOOT

FOOT DEF

DEF

I18285

LHD model:

RHD model:

FACE

DEF

FACE

DEF

DI–848

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Actuator check.

PREPARATION:
(a)

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

(b)

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

CHECK:
Press the A/C switch and check the condition of air flow.
OK:

The mode changes with the change in the tempera-
ture display as shown in the table.

OK

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

NG

2

Check air outlet damper control servomotor.

PREPARATION:
(a)

Remove A/C unit. (See page AC–63).

(b)

Disconnect the air outlet damper control servomotor as-
sembly connector.

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

The lever moves smoothly to FACE position.

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

The lever moves smoothly to DEF position.

NG

Replace air outlet servomotor.

OK

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–849

LEXUS RX300   (RM785E)

3

Check for open and short in harness and connector between A/C ECU (Combina-
tion meter ECU) and outlet servomotor, outlet damper control servomotor and
battery, outlet damper control servomotor and body ground (See page IN–32).

NG

Repair or replace harness or connector.

OK

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