Subaru Legacy (2005 year). Service manual — part 877

AC(diag)-25

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

Diagnostic Procedure for Actuators

Step

Check

Yes

No

1

CHECK POWER SUPPLY FOR INTAKE
DOOR ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the intake door actuator con-
nector.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake door
actuator connector and chassis ground.

Connector & terminal

(B91) No. 7 (+) — Chassis ground (

−

):

Is the voltage 7 V (at normal
temperature)?

Go to step 2.

Check the harness
for open or short
circuit between
intake door actua-
tor and fuse.

2

CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND INTAKE DOOR
ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the auto A/C control module
connector.
3) Measure the resistance between intake
door actuator connector and auto A/C control
module connector.

Connector & terminal

(B283) No. 10 — (B91) No. 3:
(B283) No. 20 — (B91) No. 1:

Is the resistance less than 1
Ω?

Go to step 3.

Repair the har-
ness between auto
A/C control mod-
ule and intake
door actuator.

3

CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Connect the intake door actuator connec-
tor.
2) Ground the auto A/C control module con-
nector with a suitable wire.
3) Turn the ignition switch to ON, and check
the operation of intake door actuator.

Connector & terminal

(B283) No. 10 — Chassis ground:

Does the actuator move to the
FRESH side?

Go to step 4.

Replace the intake
door actuator.

4

CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Turn the ignition switch to OFF.
2) Ground the auto A/C control module con-
nector with a suitable wire.
3) Turn the ignition switch to ON, and check
the operation of intake door actuator.

Connector & terminal:

(B283) No. 20 — Chassis ground:

Does the actuator move to the
RECIRC side?

Replace the auto
A/C control mod-
ule.

Replace the intake
door actuator.

AC(diag)-26

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

Diagnostic Procedure for Actuators

B: MODE DOOR ACTUATOR

TROUBLE SYMPTOM:
Air flow outlet is not changed.
WIRING DIAGRAM:

AC-00827

3 4

1 2

8 9 10

11 12 13 14 15 16 17 18 19 20

5 6 7

B77

B283

B:

3 4

1 2

8

9 10 11 12 13 14 15 16

5 6 7

B282

A:

B283

B282

B77

B17

AUTO A/C

CONTROL MODULE

MODE DOOR ACTUATOR

1

5

4

A15

B7

B:

A:

3

2

A8

A3

1 2 3 4 5

AC(diag)-27

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

Diagnostic Procedure for Actuators

Step

Check

Yes

No

1

CHECK POWER SUPPLY FOR MODE DOOR
ACTUATOR POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the mode door actuator con-
nector.
3) Turn the ignition switch and AUTO switch to
ON.
4) Measure the voltage between auto A/C
control module connector terminals.

Connector & terminal

(B282) No. 8 (+) — (B282) No. 15 (

−

):

Is the voltage approx. 5 V?

Go to step 2.

Replace the auto
A/C control mod-
ule.

2

CHECK POWER SUPPLY FOR MODE DOOR
ACTUATOR.
Measure the voltage between auto A/C control
module connector and chassis ground after
turning the air flow control switch to FACE posi-
tion.

Connector & terminal

(B283) No. 7 (+) — Chassis ground (

−

):

Is the voltage 7 V (at normal
temperature)?

Go to step 3.

Replace the auto
A/C control mod-
ule.

3

CHECK POWER SUPPLY FOR MODE DOOR
ACTUATOR.
Measure the voltage between auto A/C control
module connector and chassis ground after
turning the air flow control switch to DEF posi-
tion.

Connector & terminal

(B283) No. 17 (+) — Chassis ground (

−

):

Is the voltage 7 V (at normal
temperature)?

Go to step 4.

Replace the auto
A/C control mod-
ule.

4

CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND MODE DOOR AC-
TUATOR.
1) Turn the A/C and ignition switch to OFF.
2) Disconnect the auto A/C control module
connector.
3) Measure the resistance between auto A/C
control module and mode door actuator con-
nector.

Connector & terminal

(B77) No. 1 — (B282) No. 15:
(B77) No. 2 — (B282) No. 8:
(B77) No. 3 — (B282) No. 3:
(B77) No. 4 — (B283) No. 17:
(B77) No. 5 — (B283) No. 7:

Is the resistance less than 1
Ω?

Go to step 5.

Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.

5

CHECK MODE DOOR ACTUATOR POSI-
TION SWITCH SIGNAL.
1) Connect the connector of auto A/C control
module and mode door actuator.
2) Turn the ignition switch and AUTO switch to
ON.
3) Check the voltage between auto A/C con-
trol module connector terminals while chang-
ing the mode between DEF and FACE.

Connector & terminal

(B282) No. 3 (+) — (B282) No. 15 (

−

):

Does the voltage change
between 1 (DEF) — 4 (FACE)
V?

Go to step 6.

Replace the mode
door actuator.

6

CHECK POOR CONTACT.
Check poor contact in auto A/C control module
and connector.

Is there poor contact in con-
nector?

Repair connector.

Replace the auto
A/C control mod-
ule.

AC(diag)-28

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

Diagnostic Procedure for Actuators

C: AIR MIX DOOR ACTUATOR

TROUBLE SYMPTOM:
Outlet air temperature does not change.
WIRING DIAGRAM:

AC-00828

3 4

1 2

8 9 10

11 12 13 14 15 16 17 18 19 20

5 6 7

B235

B283

B:

3 4

1 2

8

9 10 11 12 13 14 15 16

5 6 7

B282

A:

B283

B282

B235

B8

3

7

6

A15

B18

B:

A:

5

1

A8

A4

1

3 4 5

7

2

6

AUTO A/C

CONTROL MODULE

AIR MIX DOOR ACTUATOR