Subaru Legacy III (2000-2003 year). Service manual — part 871
AC-20
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
DIAGNOSTICS FOR A/C SYSTEM FAILURE (LHD MODEL)
7. Diagnostics for A/C System Failure (LHD 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-00318
A8
B2
B1
B12
i48
A:
i49
B:
AUTO A/C CONTROL MODULE
BATTERY
NO. 17
NO. 4
NO. 2
SBF-1
100A
SBF-4
i48
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16
i49
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
A:
B:
IGNITION
SWITCH
i28
AC-21
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
DIAGNOSTICS FOR A/C SYSTEM FAILURE (LHD 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-out.
Replace fuse.
2
CHECK FUSE.
1) Turn ignition switch to OFF.
2) Remove fuses No. 4 and No. 17 from fuse
& relay box.
3) Check condition of fuse.
Is the fuse blown-out?
Fuse is not blown-out.
Replace fuse.
3
CHECK A/C CONTROL MODULE POWER
CIRCUIT.
1) Disconnect A/C control module connector.
2) Measure voltage between A/C control mod-
ule connector terminal and chassis ground
when turning ignition switch to OFF.
Connector & terminal
(i49) No. 1 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the spec-
ified value?
10 V
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
(i49) No. 2 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the specified
value?
10 V
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. 8 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the specified
value?
10 V
Repair harness for
power supply line.
6
CHECK A/C CONTROL MODULE GROUND
CIRCUIT.
Measure resistance of harness between A/C
control module and chassis ground.
Connector & terminal
(i49) No. 12 — Chassis ground:
Is the measured value less than the specified
value?
1
Ω
Repair harness for
ground line.
7
CHECK POOR CONTACT.
Check poor contact in A/C control module con-
nector.
Is there poor contact in connector?
There is no poor contact.
Replace A/C con-
trol module.
Repair connector.
AC-22
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
DIAGNOSTICS FOR A/C SYSTEM FAILURE (LHD MODEL)
B: BLOWER MOTOR DOES NOT ROTATE
TROUBLE SYMPTOM:
• Blower motor does not rotate.
• Blower motor does not rotate in “HI”.
WIRING DIAGRAM:
AC-00319
A16
B11
B14
B50
B87
B86
B80
B36
i1
i20
BATTERY
NO. 1
NO. 2
NO. 17
SBF-3
SBF-1
SBF-4
i48
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16
i49
1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
A:
B:
2
1
4
2
1
3
4
1
2
BLOWER MOTOR
RESISTOR
BLOWER MOTOR
BLOWER MOTOR
RELAY
IGNITION
SWITCH
2
8
A6
B50
3 4
1 2
1 2 3 4
5 6 7 8
i20
B87
1
2
B86
3 4
1 2
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
i48
A:
i49
B:
AUTO A/C CONTROL MODULE
AC-23
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
DIAGNOSTICS FOR A/C SYSTEM FAILURE (LHD MODEL)
Step
Value
Yes
No
1
CHECK FUSE.
1) Remove No. 1, No. 2 and No. 17 fuses in
fuse & relay box.
2) Check condition of fuses.
Are any of the fuses blown-out?
Fuse is not blown-out.
Replace fuse.
2
CHECK POWER SUPPLY TO BLOWER FAN
MOTOR.
1) Turn ignition switch to ON.
2) Turn blower switch to ON.
3) Measure voltage between blower fan motor
and chassis ground.
Connector & terminal
(B87) No. 1 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the spec-
ified value?
10 V
Repair harness for
blower fan motor
power supply line.
3
CHECK BLOWER FAN MOTOR RELAY.
1) Turn ignition switch to OFF.
2) Remove blower fan motor relay.
3) Connect terminals as follows:
Positive terminal (+) of battery to terminal
No. 1 of blower fan motor relay
Negative terminal (
−
) of battery to terminal
No. 3 of blower fan motor relay
4) Measure resistance between No. 2 and No.
4 terminals.
Terminals
No. 2 — No. 4:
Is the measured value less than the speci-
fied value?
1
Ω
Replace blower
fan motor relay.
4
CHECK BLOWER FAN MOTOR.
1) Disconnect connector from blower fan
motor.
2) Connect terminals as follows:
Positive terminal (+) of battery to terminal
No. 1 of blower fan motor relay
Negative terminal (
−
) of battery to terminal
No. 2 of blower fan motor relay
3) Make sure that blower fan motor is oper-
ated.
Does the blower fan motor operate?
Blower fan motor operates.
Replace blower
fan motor.
5
CHECK POOR CONTACT.
Check poor contact in A/C control module con-
nector.
Is there poor contact in connector?
There no poor contact.
Replace A/C con-
trol module.
Repair connector.
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