Subaru Legacy IV (2008 year). Manual — part 992

AC(diag)-20

Diagnostics for A/C System Malfunction

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

7

CHECK A/C ON SIGNAL.
1) Turn the ignition switch to OFF.
2) Connect the A/C relay and all disconnected
connectors.
3) Start the engine and turn the AUTO switch
to ON.
4) Turn the temperature control dial at maxi-
mum cool position.
5) Measure the voltage between auto A/C con-
trol module harness connector terminal and
chassis ground.

Connector & terminal

(B282) No. 15 (+) — Chassis ground (–):

Is the voltage 5.5 V or more?

Go to step 9.

Go to step 8.

8

CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the harness connector of auto
A/C control module and ECM.
3) Measure the resistance of harness between
auto A/C control module connector and ECM
connector.

Connector & terminal

(B282) No. 15 — (B136) No. 24:

Is the resistance less than 1

:? Replace the auto

A/C control mod-
ule.

Repair the har-
ness.

9

CHECK MAGNET CLUTCH ON SIGNAL.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor terminal and chassis ground.

Connector & terminal

(B136) No. 9 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 10.

Check for open or
short circuit in the
harness between
A/C relay and
ECM.

10

CHECK MAGNET CLUTCH ON SIGNAL.
1) Start the engine and turn the AUTO switch
to ON.
2) Turn the temperature control dial at maxi-
mum cool position.
3) Measure the voltage between ECM connec-
tor terminal and chassis ground.

Connector & terminal

(B136) No. 9 (+) — Chassis ground (–):

Is the voltage 0 V?

Go to step 11.

Replace the ECM.

11

CHECK POWER SUPPLY FOR MAGNET
CLUTCH.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Disconnect the harness connector of mag-
net clutch.
3) Start the engine and turn the AUTO switch
to ON.
4) Turn the temperature control dial at maxi-
mum cool position.
5) Measure the voltage between magnet
clutch harness connector terminal and chassis
ground.

Connector & terminal

(F24) No. 1 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 12.

Check for open or
short circuit in the
harness between
A/C relay and mag-
net clutch.

Step

Check

Yes

No

AC(diag)-21

Diagnostics for A/C System Malfunction

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

12

CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND ECM.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Measure the resistance between magnet
clutch harness connector terminal and chassis
ground.

Connector & terminal

(F24) No. 2 — Chassis ground:

Is the resistance less than 1

:? Inspect the com-

pressor. <Ref. to
AC-36, INSPEC-
TION, Compres-
sor.>

Repair the har-
ness.

Step

Check

Yes

No

AC(diag)-22

Diagnostic Procedure for Actuators

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

7. Diagnostic Procedure for Actuators

A: INTAKE DOOR ACTUATOR

TROUBLE SYMPTOM:
FRESH/RECIRC mode is not changed.
WIRING DIAGRAM:

AC-01646

B91

MAIN SBF

SBF-6

F/B No.22

7

3

1

B282

40

20

B91

B282

1 2 3 4 5 6 7

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

BATTERY

IGNITION
SWITCH

INTAKE DOOR

ACTUATOR

AUTO A/C

CONTROL MODULE

AC(diag)-23

Diagnostic Procedure for Actuators

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

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 for open or
short circuit in the
harness 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

(B282) No. 20 — (B91) No. 3:
(B282) No. 40 — (B91) No. 1:

Is the resistance less than 1

:? Go to step 3.

Repair the harness
between auto A/C
control module and
intake door actua-
tor.

3

CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Connect the intake door actuator connector.
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

(B282) No. 20 — 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

(B282) No. 40 — Chassis ground:

Does the actuator move to the
RECIRC side?

Replace the auto
A/C control mod-
ule.

Replace the intake
door actuator.