Subaru Legacy III (2000-2003 year). Manual — part 874

AC-32

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

DIAGNOSTICS FOR A/C SYSTEM FAILURE (RHD MODEL)

8. Diagnostics for A/C System Failure (RHD Model)

A: A/C AND/OR SELF-DIAGNOSIS SYSTEMS DO NOT OPERATE

TROUBLE SYMPTOM:
• “Set” temperature is not indicated on display, switch LEDs are faulty and switches do not operate.
• Self-diagnosis system does not operate.
WIRING DIAGRAM:

AC-00366

A2

A3

A1

A9

i48

A:

i49

B:

AUTO A/C CONTROL MODULE

BATTERY

NO. 17

NO. 4

NO. 2

SBF-1 100A

SBF-4

i48

i28

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

A:

IGNITION

SWITCH

AC-33

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

DIAGNOSTICS FOR A/C SYSTEM FAILURE (RHD MODEL)

Step

Value

Yes

No

1

CHECK FUSE.
1) Turn ignition switch to OFF.
2) Remove fuse No. 2 from main fuse box.
3) Check condition of fuse.

Is the fuse blown-out?

Fuse is not blown.

Go to step 2.

Replace fuse.

2

CHECK FUSE.
1) Remove fuse No. 4 and No. 17 from fuse &

relay box.

2) Check condition of fuse.

Is the fuse blown-out?

Fuse is not blown.

Go to step 3.

Replace fuse.

3

CHECK A/C CONTROL MODULE POWER
CIRCUIT.
1) Disconnect A/C control module.
2) Measure voltage between A/C control mod-

ule connector terminal and chassis ground
when turning ignition switch to OFF.

Connector & terminal

(i48) No. 1 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 4.

Repair harness for
power supply line.

4

CHECK A/C CONTROL MODULE POWER
CIRCUIT.
Measure voltage between A/C control module
connector terminal and chassis ground when
turning ignition switch to ACC.

Connector & terminal

(i48) No. 3 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Go to step 5.

Repair harness for
power supply line.

5

CHECK A/C CONTROL MODULE POWER
CIRCUIT.
Measure voltage between A/C control module
connector terminal and chassis ground when
turning ignition switch to ON.

Connector & terminal

(i48) No. 2 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Go to step 6.

Repair harness for
power supply line.

6

CHECK A/C CONTROL MODULE CIRCUIT.
Measure resistance of harness between A/C
control module and chassis ground.

Connector & terminal

(i48) No. 9 (+) — Chassis ground (

−−−−

):

Is the measured value less than the specified
value?

10 V

Go to step 7.

Repair harness
ground line.

7

CHECK POOR CONTACT.
Check poor contact in A/C control module con-
nector.
Is there poor contact in A/C control module?

There is no poor contact.

Replace A/C con-
trol module.

Repair connector.

AC-34

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

DIAGNOSTICS FOR A/C SYSTEM FAILURE (RHD MODEL)

B: BLOWER MOTOR DOES NOT ROTATE

TROUBLE SYMPTOM:
• Blower motor does not rotate.
• Blower motor does not rotate in “HI”.
WIRING DIAGRAM:

AC-00367

BATTERY

NO. 1

NO. 2

NO. 17

SBF-1

SBF-3

SFB-4

A15

B5

B3

A6

B36

i1

AUTO A/C

CONTROL

MODULE

A:

i49

i48

B:

i52

B1

3

2

1

BPC

7

3

2

12

B2

1

2

i52

1 2

3 4

5 6

7

8 9

10 11 12 13 14

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

B:

i49

3
4

1

2

i28

B80

B50

i20

B36

B4 B5 B6

A4 A5 A6

C5 C6

F6

D4 D5 D6

F1

H1

C4

G6

G1

C2

K1

M1 M2

K6

L1

D1 D2

A1 A2
B1 B2

I6

J6

L2

I1

J1

H6

M4 M5 M6

L4 L5 L6

N5 N6

O4 O5 O6

N4

P4 P5

N2

O1 O2

P1 P2

N3

O3

P3

P6

A3

B3

C3

E4 E5 E6

E1 E2

BLOWER MOTOR
RELAY

B50

3 4

1 2

1 2 3 4
5 6 7 8

i20

2 3

1

B1

i48

A:

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

IGNITION

SWITCH

B2

1 2

B3

1
2

1
2

1

B3

BLOWER
MOTOR

2

1

BLOWER MODULE

AC-35

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)

DIAGNOSTICS FOR A/C SYSTEM FAILURE (RHD MODEL)

Step

Value

Yes

No

1

CHECK FUSE.
1) Turn ignition switch to OFF.
2) Remove No. 1, No. 2 and No. 17 fuses in

fuse & relay box.

3) Check condition of each fuse.

Are any of the fuses blown-out?

Fuse is not blown.

Go to step 2.

Replace fuse.

2

CHECK POWER SUPPLY TO BLOWER FAN
MOTOR.
1) Turn ignition switch to ON.
2) Turn blower switch to ON (Hi).
3) Measure voltage between blower fan motor

and chassis ground.

Connector & terminal

(B1) No. 3 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 3.

Go to step 7.

3

CHECK RESISTANCE BETWEEN BPC AND
CHASSIS GROUND.
Measure resistance between BPC connector
and chassis ground.

Connector & terminal

(B1) No. 1 — Chassis ground:

Is the measured value less than the specified
value?

1

Ω

Go to step 4.

Repair harness
between BPC and
chassis ground.

4

CHECK BPC.
Measure voltage between BPC connector and
chassis ground.

Connector & terminal

(B1) No. 2 (+) — Chassis ground (

−−−−

):

Is the measured value same as the specified
value?

Approximately 0 V

Go to step 5.

Replace BPC.

5

CHECK BPC.
Measure voltage between BPC connector.

Connector & terminal

(B2) No. 1 (+) — (B2) No. 2 (

−−−−

):

Does the measured value exceed as the spec-
ified value?

10 V

Go to step 6.

Replace BPC.

6

CHECK A/C CONTROL MODULE.
Measure voltage between A/C control module
connector and chassis ground.

Connector & terminal

(i49) No. 5 (+) — Chassis ground (-):

Is the measured value same as the specified
value?

Approx. 0 V

Go to step 7.

Go to step 10.

7

CHECK A/C CONTROL MODULE.
Measure voltage between A/C control module
connector and chassis ground.

Connector & terminal

(i49) No. 3 (+) — Chassis ground (-):

Is the measured value same as the specified
value?

Approx. 0 V

Go to step 8.

Go to step 10.