Subaru Legacy 2005 Service Manual page 3526

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step
1 CHECK IN-VEHICLE SENSOR.
1) Turn the ignition switch to OFF.
2) Remove the driver's side lower cover.
3) Disconnect the connector from in-vehicle
sensor.
4) Measure the resistance between connector
terminals of in-vehicle sensor.
Terminals
No. 1 — No. 2:
2 CHECK INPUT SIGNAL FOR IN-VEHICLE
SENSOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between connector
(i55) terminals.
Connector & terminal
(i55) No. 2 (+) — No. 1 (
3 CHECK AUTO A/C CONTROL MODULE
OUTPUT SIGNAL.
1) Turn the ignition switch to OFF.
2) Remove the auto A/C control module.
3) Turn the ignition switch to ON.
4) Measure the voltage between connector
terminals of auto A/C control module.
Connector & terminal
(B282) No. 5 (+) — (B282) No. 15 (
4 CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND IN-VEHICLE SEN-
SOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from auto A/C
control module.
3) Measure the resistance in harness
between auto A/C control module and in-vehi-
cle sensor.
Connector & terminal
(i55) No. 2 — (B282) No. 5:
5 CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND IN-VEHICLE SEN-
SOR.
Measure the resistance in harness between
auto A/C control module and in-vehicle sensor.
Connector & terminal
(i55) No. 1 — (B282) No. 15:
6 CHECK POOR CONTACT.
Check poor contact in auto A/C control module
connector.
Diagnostic Procedure for Sensors
Is the resistance approx. 2.7
kΩ at 20°C (68°F)?
Is the voltage approx. 5 V?
−
):
Is the voltage approx. 5 V?
−
):
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in con-
nector?
AC(diag)-34
Check
Go to step 2.
Go to step 6.
Go to step 4.
Go to step 5.
Go to step 6.
Repair the con-
nector.
Yes No
Replace the in-
vehicle sensor.
Go to step 3.
Go to step 6.
Repair the har-
ness between auto
A/C control mod-
ule and in-vehicle
sensor.
Repair the har-
ness between auto
A/C control mod-
ule and in-vehicle
sensor.
Replace the auto
A/C control mod-
ule.