Subaru Legacy III (2000-2003 year). Service 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.
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.
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
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
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
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
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.
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
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
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
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
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
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
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