Subaru Impreza 2004 Service Manual page 26

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step
1 CHECK FUSE.
1)Remove the No. 17 fuse in fuse & relay box.
2)Check the condition of fuse.
2 CHECK SIGNAL VOLTAGE.
1)Change the air intake to RECIRC by pushing
FRESH/RECIRC switch.
2)Measure the voltage between A/C control
module and chassis ground.
Connector & terminal
(B282) No. 15 (+) — Chassis ground ( − − − − ):
3 CHECK SIGNAL VOLTAGE.
1)Change the air intake to FRESH with push-
ing FRESH/RECIRC switch.
2)Measure the voltage between A/C control
module and chassis ground.
Connector & terminal
(B282) No. 7 (+) — Chassis ground ( − − − − ):
4 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND FRESH/RE-
CIRC ACTUATOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from A/C control
module and intake door actuator.
3)Measure the resistance of harness between
A/C control module and intake door actuator.
Connector & terminal
(B282) No. 15 — (B91) No. 1:
5 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND FRESH/RE-
CIRC ACTUATOR.
Measure the resistance of harness between A/
C control module and intake door actuator.
Connector & terminal
(B282) No. 7 — (B91) No. 2:
6 CHECK POOR CONTACT.
Check poor contact in A/C control module con-
nector.
Diagnostic Procedure for Actuators
Is the fuse blown-out?
Is the voltage less than 1 V?
Is the voltage less than 1 V?
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in con-
nector?
AC(diag)-24
Check
Replace the fuse.
Go to step 3.
Go to step 4.
Go to step 5.
Go to step 6.
Repair the con-
nector.
Yes No
Go to step 2.
Repair the short
circuit in harness
for power supply
line.
Repair the short
circuit in harness
for power supply
line.
Repair the open
circuit in harness
between A/C con-
trol module and
intake door actua-
tor.
Repair the open
circuit in harness
between A/C con-
trol module and
intake door actua-
tor.
Replace the A/C
control module.