Subaru Legacy III (2000-2003 year). Manual — part 279

CO(H6DO)-14

COOLING

RADIATOR SUB FAN SYSTEM

3. Radiator Sub Fan System

A: SCHEMATIC

CO-00167

2

1

4

3

28

27

25

29

8

7

5

9

31

32

34

30

21

22

24

20

30A

30A

SUB FAN

RELAY-1

AIR CONDITIONING RELAY HOLDER

SUB FAN

MOTOR

MAIN FAN

MOTOR

MAIN FAN

RELAY-1

F28

F16

F66

SUB FAN

RELAY-2

MAIN FAN

RELAY-2

F29

F30

F27

F17

B100

F2

B72

NO. 18

NO. 17

SBF-4

SBF-1

IGNITION
SWITCH

RELAY HOLDER (BLACK)

B72

F16

B253

F17

F46

3 4

1 2

B137

BATTERY

17

24

28

B137

ENG

INE C

O

NTR

O

L

M

O

DU

LE

B253

FAN RELAY

5
1
3
4

3

3

4

4

1

1

2

2

1

2

7

8

9

5

6

3

4

10 11 12

19 20 21
29 30 31

13 14 15 16 17

27 28

18

22 23 24 25 26

3 4

1 2

1

3

4

5

2

1

F46

B108

1

F44

B61

LHD

LHD

RHD

RHD

1

*

2

*

1

*

2

*

LHD : 7

LHD : 6

RHD : 5

RHD : 6

1 2 3 4
5 6 7 8

F44

F2

3 4

1 2

8 9 10 11

12 13 14 15 16 17 18 19 20 21 22 23 24

5 6

7

1

2

5 6

8
9

7

3

4

25 26 27

28
29

30
31

32 33 34

10
11

12 13 14

15 16 17

18
19

20
21

22 23 24

35

36

F30

F28

F29

F66

F27

CO(H6DO)-15

COOLING

RADIATOR SUB FAN SYSTEM

B: INSPECTION

TROUBLE SYMPTOM:
• Radiator sub fan does not rotate in low speed under the following conditions:

(1) Coolant temperature 98 — 101

°

C (208 — 214

°

F).

(2) A/C switch set to OFF.

• Radiator sub fan does not rotate in middle speed under the following conditions:

(1) Coolant temperature 97

°

C (207

°

F) or less.

(2) A/C switch set to ON and A/C temperature at the lowest position.

• Radiator sub fan does not rotate in high speed under the following conditions:

(1) Coolant temperature 98 — 101

°

C (208 — 214

°

F).

(2) A/C switch set to ON and A/C temperature at the lowest position.

Step

Value

Yes

No

1

CHECK OPERATION OF RADIATOR FAN.
1) Run the engine at idle (Vehicle stationary)
2) Turn the A/C switch to ON, set temperature

at the lowest position.

3) Inspect while coolant temperature is 97

°

C

(207

°

F) or less.

When A/C compressor is operating, does
the radiator sub fan rotate in middle speed?

Rotates in middle speed.

Go to step 2.

Go to step 4.

2

CHECK OPERATION OF RADIATOR FAN.
1) Turn the A/C switch to OFF.
2) Perform checking procedure during coolant

temperature is 98 — 101

°

C (208 — 214

°

F).

When A/C compressor is operating, does
the radiator sub fan rotate in low speed?

Rotates in low speed.

Go to step 3.

Go to step 18.

3

CHECK OPERATION OF RADIATOR FAN.
1) Turn the A/C switch to ON, set temperature

at the lowest position.

2) Perform checking procedure during coolant

temperature is 98 — 101

°

C (208 — 214

°

F).

When A/C compressor is operating, does
the radiator sub fan rotate in high speed?

Rotates in high speed.

Radiator sub fan
system is okay.

Go to step 31.

4

CHECK POWER SUPPLY TO SUB FAN MO-
TOR.

CAUTION:

Be careful not to overheat engine during re-
pair.

1) Turn ignition switch to OFF.
2) Disconnect connector from sub fan motor.
3) Start the engine, keep coolant temperature

below 97

°

C (207

°

F).

4) Turn the A/C switch to ON, set temperature

at the lowest position.

5) Measure voltage while A/C compressor is

rotating.

6) Measure voltage between sub fan motor

connector and chassis ground.

Connector & terminal

(F16) No. 1 (+) — Chassis ground (

−−−−

):

(F16) No. 2 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 5.

Go to step 8.

CO(H6DO)-16

COOLING

RADIATOR SUB FAN SYSTEM

5

CHECK GROUND CIRCUIT OF SUB FAN
MOTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between sub fan motor

connector and chassis ground.

Connector & terminal

(F16) No. 4 — Chassis ground:

Is the measured value less than the speci-
fied value?

5

Ω

Go to step 6.

Repair open circuit
in harness
between sub fan
motor connector
and chassis
ground.

6

CHECK POOR CONTACT.
Check poor contact in sub fan motor connec-
tor.
Is there poor contact in sub fan motor connec-
tor?

There is poor contact.

Repair poor con-
tact in sub fan
motor connector.

Go to step 7.

7

CHECK SUB FAN MOTOR.
Connect battery positive (+) terminal to termi-
nals No. 1 and No. 2 and negative (

−

) terminal

to terminal No. 4 of sub fan motor connector.
Does the sub fan rotate?

Rotates.

Repair poor con-
tact in sub fan
motor connector.

Replace sub fan
motor with a new
one.

8

CHECK POWER SUPPLY TO SUB FAN RE-
LAYS 1 AND 2.
1) Remove sub fan relays 1 and 2 from A/C

relay holder.

2) Turn ignition switch to ON.
3) Measure voltage between sub fan relays 1

and 2 terminal and chassis ground.

Connector & terminal

(F28) No. 28 (+) — Chassis ground (

−−−−

):

(F29) No. 31 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 9.

Go to step 10.

9

CHECK POWER SUPPLY TO SUB FAN RE-
LAYS 1 AND 2.
Measure voltage between sub fan relays 1 and
2 terminal and chassis ground.

Connector & terminal

(F28) No. 25 (+) — Chassis ground (

−−−−

):

(F29) No. 34 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Go to step 13.

Go to step 12.

10

CHECK 30 A FUSE.
1) Remove 30 A fuse from A/C relay holder.
2) Check condition of fuse.

Is the fuse blown-out?

Fuse is blown-out.

Replace fuse.

Go to step 11.

11

CHECK POWER SUPPLY TO A/C RELAY
HOLDER 30 A FUSE TERMINAL.
Measure voltage of harness between A/C relay
holder 30 A fuse terminal and chassis ground.

Connector & terminal

(F27) No. 3 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the specified
value?

10 V

Repair open circuit
in harness
between 30 A fuse
and sub fan relays
1 and 2 terminal.

Repair open circuit
in harness
between main fuse
box connector and
30 A fuse terminal.

12

CHECK FUSE.
1) Turn ignition switch to OFF.
2) Remove fuse No. 17 from joint box.
3) Check condition of fuse.

Is the fuse blown-out?

Fuse is blown-out.

Replace fuse.

Repair open circuit
in harness
between sub fan
relays 1 and 2 and
ignition switch.

Step

Value

Yes

No

CO(H6DO)-17

COOLING

RADIATOR SUB FAN SYSTEM

13

CHECK SUB FAN RELAYS 1 AND 2.
1) Turn ignition switch to OFF.
2) Remove sub fan relays 1 and 2.
3) Measure resistance of sub fan relays 1 and

2.

Terminal

No. 28 — No. 29:
No. 30 — No. 31:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 14.

Replace sub fan
relays 1 and 2.

14

CHECK SUB FAN RELAYS 1 AND 2.
1) Connect battery to terminals No. 25 and

No. 27 of sub fan relay 1 or to terminals No.
32 and No. 34 of sub fan relay 2.

2) Measure resistance of sub fan relays 1 and

2.

Terminal

No. 28 — No. 29:
No. 30 — No. 31:

Is the measured value less than the speci-
fied value?

1

Ω

Go to step 15.

Replace sub fan
relays 1 and 2.

15

CHECK HARNESS BETWEEN SUB FAN RE-
LAYS 1 AND 2 TERMINAL AND SUB FAN
MOTOR CONNECTOR.
Measure resistance of harness between sub
fan motor connector and sub fan relays 1 and
2 terminal.

Connector & terminal

(F16) No. 1 — (F28) No. 29:
(F16) No. 2 — (F29) No. 30:

Is the measured value less than the specified
value?

1

Ω

Go to step 16.

Repair open circuit
in harness
between sub fan
motor connector
and sub fan relays
1 and 2 terminal.

16

CHECK HARNESS BETWEEN SUB FAN RE-
LAYS 1 AND 2 AND ECM.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between

sub fan relays 1 and 2 connector and ECM
connector.

Connector & terminal

(F28) No. 27 — (B137) No. 28:
(F29) No. 32 — (B137) No. 17:

Is the measured value less than the speci-
fied value?

1

Ω

Go to step 17.

Repair open circuit
in harness
between sub fan
relays 1 and 2 and
ECM.

17

CHECK POOR CONTACT.
Check poor contact in connector between sub
fan and ECM.
Is there poor contact in connector between sub
fan motor and ECM.

There is poor contact.

Repair poor con-
tact connector.

Contact SUBARU
distributor service.

Step

Value

Yes

No