Subaru Impreza 2002 Service Manual page 3248

Step
1 CHECK EVAPORATOR SENSOR.
1)Turn the ignition switch to OFF.
2)Remove the glove box.
3)Disconnect the connector from evaporator
sensor.
4)Measure the resistance between connector
terminals of evaporator sensor.
Terminals:
No. 1 — No. 2
2 CHECK INPUT SIGNALS FOR EVAPORA-
TOR SENSOR.
1)Turn the ignition switch to "ON".
2)Measure the voltage between (B88) connec-
tor terminal and chassis ground.
Connector & terminal
(B256) No. 2 (+) — Chassis ground ( − − − − ):
3 CHECK OUTPUT SIGNALS FROM A/C CON-
TROL MODULE.
1)Turn the ignition switch to OFF.
2)Pull out the A/C control module.
3)Turn the ignition switch to "ON".
4)Measure the voltage between A/C control
module connector terminals.
Connector & terminal:
(B283) No. 7 (+) — No. 17 ( − − − − )
4 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND EVAPORA-
TOR 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 evaporator sensor.
Connector & terminal:
(B256) No. 2 — (B283) No. 7
5 CHECK HARNESS CONNECTOR BETWEEN
A/C CONTROL MODULE AND EVAPORA-
TOR SENSOR.
Measure the resistance of harness between
A/C control module and evaporator sensor.
Connector & terminal:
(B256) 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. 3.3
kΩ at 20°C (68°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-43
Yes
Go to step 2. Replace the evap-
orator sensor.
Go to step 3. Replace the evap-
orator sensor.
Go to step 4. Go to step 6.
Go to step 5. Repair the open
circuit in harness
between A/C con-
trol module and
evaporator sensor.
Go to step 6. Repair the open
circuit in harness
between A/C con-
trol module and
evaporator sensor.
Repair the poor Contact with your
contact in A/C con- Subaru distributor
trol module. service.
No