Subaru Impreza 2004 Service Manual page 17

Step
1 CHECK FUSE.
1)Remove the No.1, No. 2 and No. 17 fuses in
fuse & relay box.
2)Check the condition of fuses.
2 CHECK POWER SUPPLY TO BLOWER FAN
MOTOR.
1)Turn the ignition switch to ON.
2)Turn the blower switch to ON.
3)Measure the voltage between blower fan
motor and chassis ground.
Connector & terminal
(B87) No. 1 (+) — Chassis ground ( − − − − ):
3 CHECK BLOWER FAN MOTOR RELAY.
1)Turn the ignition switch to OFF.
2)Remove the blower fan motor relay.
3)Connect the battery positive (+) terminal to
No. 1 terminal and negative (−) terminal to No.
3 terminal of blower fan motor connector.
4)Measure the resistance between No. 2 and
No. 4 terminals.
Terminals
No. 2 — No. 4:
4 CHECK BLOWER FAN MOTOR.
1)Disconnect the connector from blower fan
motor.
2)Connect the battery positive (+) terminal to
No.1 terminal and negative (−) terminal to No.2
terminal of blower fan motor connector.
3)Make sure that the blower fan motor is oper-
ated.
5 CHECK POOR CONTACT.
Check poor contact in A/C control module con-
nector.
Diagnostics for A/C System Malfunction
Are any of the fuses blown-
out?
Is the voltage more than 10 V? Go to step 3.
Is the resistance less than 1
Ω?
Does the blower fan motor
operate?
Is there poor contact in con-
nector?
AC(diag)-15
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Check
Replace the fuse.
Go to step 4.
Go to step 5.
Repair the con-
nector.
Yes No
Go to step 2.
Repair the open
circuit in harness
for blower fan
motor power sup-
ply line.
Replace the
blower fan motor
relay.
Replace the
blower fan motor.
Replace the A/C
control module.