Subaru Legacy 2003 Service Manual page 3508

DIAGNOSTICS FOR A/C SYSTEM FAILURE (RHD MODEL)
Step
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?
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?
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?
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?
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?
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?
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?
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Value
Fuse is not blown.
10 V
1 Ω
Approximately 0 V
10 V
Approx. 0 V
Approx. 0 V
AC-35
Yes
Go to step 2. Replace fuse.
Go to step 3. Go to step 7.
Go to step 4. Repair harness
between BPC and
chassis ground.
Go to step 5. Replace BPC.
Go to step 6. Replace BPC.
Go to step 7. Go to step 10.
Go to step 8. Go to step 10.
No