Subaru Impreza 2002 Service Manual page 3244

Step
1 CHECK AMBIENT SENSOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from ambient sen-
sor.
3)Measure the resistance between connector
terminals of ambient sensor.
Terminals:
No. 1 — No. 2
2 CHECK INPUT SIGNALS FOR AMBIENT
SENSOR.
1)Turn the ignition ON.
2)Measure the voltage between (F78) connec-
tor terminals.
Connector & terminal:
(F78) No. 1 — No. 2
3 CHECK OUTPUT SIGNALS FROM A/C CON-
TROL MODULE.
1)Turn the ignition switch to OFF.
2)Pull out the A/C control panel.
3)Disconnect the connector from ambient sen-
sor.
4)Turn the ignition switch to ON.
5)Measure the voltage between connector ter-
minals of A/C control module.
Connector & terminal:
(B283) No. 9 (+) — No. 17 ( − − − − )
4 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND AMBIENT
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 ambient sensor.
Connector & terminal
LHD model:
(F78) No. 1 — (B283) No. 9
RHD model:
(F78) No. 2 — (B283) No. 9
5 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND AMBIENT
SENSOR.
Measure the resistance of harness between
A/C control module and ambient sensor.
Connector & terminal
LHD model:
(F78) No. 2 — (B283) No. 17
RHD model:
(F78) No. 1 — (B283) No. 17
6 CHECK POOR CONTACT.
Check poor contact in A/C control module.
DIAGNOSTIC PROCEDURE FOR SENSORS
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Check
Is the resistance approx. 2.2
kΩ at 25°C (77°F)?
Is the voltage approx. 4.5 V?
Is the voltage approx. 4.5 V?
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in A/C
control module?
AC-39
Yes
Go to step 2. Replace the ambi-
ent sensor.
Go to step 6. Go to step 3.
Go to step 6. Go to step 4.
Go to step 5. Repair the open
circuit in harness
between A/C con-
trol module and
ambient sensor.
Go to step 6. Repair the open
circuit in harness
between A/C con-
trol module and
ambient sensor.
Repair the poor Contact with your
contact in A/C con- Subaru distributor
trol module. service.
No