Subaru Legacy 2002 Service Manual page 3199

DIAGNOSTICS FOR A/C SYSTEM FAILURE (RHD MODEL)
HVAC System (Auto A/C) (Diagnostics)
No.
1 CHECK FUSE.
1) Turn ignition switch to OFF.
2) Remove No. 2 fuse in main fuse.
3) Check condition of fuse.
2 CHECK POWER SUPPLY TO MAGNET
CLUTCH OF A/C COMPRESSOR.
1) Start the engine, and turn A/C switch to
ON.
2) Set the compartment temperature at 18°C
(65°F) (MAX COOL).
3) Measure voltage between magnet clutch
connector and chassis ground.
Connector & terminal
(F82) No. 1 (+) — Chassis ground (−):
3 CHECK SIGNAL VOLTAGE TO A/C RELAY.
1) Turn ignition switch to ON.
2) Turn A/C switch to ON.
3) Measure signal voltage to A/C relay.
Connector & terminal
(F31) No. 9 (+) — Chassis ground (−):
4 CHECK A/C RELAY.
1) Remove A/C relay in main fuse box.
2) Check A/C relay. <Ref. to AC-44,
INSPECTION, Relay and Fuse.>
5 CHECK OPERATION OF MAIN FAN
MOTOR.
1) Start the engine.
2) Turn A/C switch to ON.
3) Check operation of main fan motor.
6 CHECK POWER SUPPLY TO MAIN FAN
MOTOR.
CAUTION:
Be careful not to overheat engine during
repair.
1) Turn ignition switch to OFF.
2) Disconnect connector from main fan motor.
3) Start the engine, and warm it up until
engine coolant temperature increases over
95°C (203°F).
4) Stop the engine and turn ignition switch to
ON.
5) Measure voltage between main fan motor
connector and chassis ground.
Connector & terminal
4 CYLINDER ENGINE MODEL
(F17) No. 2 (+) — Chassis ground (−):
6 CYLINDER ENGINE MODEL
(F17) No. 1, 2, 3 (+) — Chassis ground
(−):
7 CHECK GROUND CIRCUIT OF MAIN FAN
MOTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between main fan
motor connector and chassis ground.
Connector & terminal
4 CYLINDER ENGINE MODEL
(F17) No. 1 — Chassis ground:
6 CYLINDER ENGINE MODEL
(F17) No. 4 — Chassis ground:
Step
Is the fuse blown-out?
Is the voltage more than 10
V?
Is the voltage more than 10
V?
Is the operation of each
relay OK?
Does the radiator main fan
operate?
Is the voltage more than 10
V?
Is the resistance less than
1 Ω?
AC-56
Check Yes
Replace fuse.
Go to step 3.
Go to step 4.
Go to step 5.
Go to step 10.
Go to step 7.
Go to step 8.
No
Go to step 2.
Repair open cir-
cuit in harness for
power supply line
of the A/C com-
pressor.
Repair open cir-
cuit in harness for
power supply line.
Replace A/C relay.
Go to step 6.
Repair open cir-
cuit in harness for
power supply cir-
cuit. <Ref. to
CO-7,
SCHEMATIC,
Radiator Main
Fan System.>
Repair open cir-
cuit in harness
between main fan
motor connector
and chassis
ground. <Ref. to
CO-7,
SCHEMATIC,
Radiator Main
Fan System.>