Subaru Impreza 2004 Service Manual page 36

HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step
1 CHECK INPUT VOLTAGE TO SUNLOAD
SENSOR.
1)Turn the ignition switch to ON.
2)Measure the input voltage to sunload sensor.
Connector & terminal
(i51) No. 2 (+) — Chassis ground ( − − − − ):
2 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND SUNLOAD
SENSOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connectors from A/C control
module.
3)Measure the resistance of harness between
A/C control module and sunload sensor.
Connector & terminal
(i51) No. 2 — (B283) No. 16:
3 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND SUNLOAD
SENSOR.
Measure the resistance of harness between A/
C control module and sunload sensor.
Connector & terminal
(i51) No. 1 — (B283) No. 17:
4 CHECK THE INPUT VOLTAGE TO A/C CON-
TROL MODULE.
1)Connect the A/C control module connector.
2)Turn the ignition switch to ON.
3)Measure the voltage between A/C control
module connector terminals.
Connector & terminal
(B283) No. 16 (+) — (B283) No. 17 ( − − − − ):
5 CHECK POOR CONTACT.
Check poor contact in A/C control module con-
nector.
Diagnostic Procedure for Sensors
Is the voltage approx. 5 V?
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is the voltage approx. 2.5 V?
Is there poor contact in con-
nector?
AC(diag)-34
Check
Go to step 3.
Go to step 3.
Go to step 4.
Go to step 5.
Repair the con-
nector.
Yes No
Go to step 2.
Repair the har-
ness between A/C
control module
and sunload sen-
sor.
Repair the har-
ness between A/C
control module
and sunload sen-
sor.
Replace the sun-
load sensor.
Replace the A/C
control module.