2004 SUBARU FORESTER replace disc

AC-15
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostics for A/C System Malfunction
Step Check Yes No
1 CHECK FUSE.
1) Remove the fuse No. 1, 2 and 17 from fuse
& relay box.
2) Check the condition of fuse.Is any fuse blown-out? Replace the fuse. Go to step 2.
2 CHECK POWER SUPPLY FOR BLOWER
MOTOR.
1) Turn the ignition switch to ON.
2) Turn the fan speed control dial clockwise.
3) Measure the voltage between blower motor
and chassis ground.
Connector & terminal
(B87) No. 1 (+) — Chassis ground (
−):Is the voltage more than 8 V (at
normal temperature)?Go to step 3.Repair the open
circuit of blower
motor power sup-
ply line harness.
3 CHECK BLOWER MOTOR RELAY.
1) Turn the ignition switch to OFF.
2) Remove the blower motor relay.
3) Connect the battery positive (+) terminal to
terminal No. 1 of blower motor relay, and nega-
tive (−) terminal to terminal No. 3.
4) Measure the resistance between terminals
No. 2 and 4.
Te r m i n a l s
No. 2 — No. 4:Is the resistance less than 1
Ω?Go to step 4.Replace the
blower motor relay.
4 CHECK BLOWER MOTOR.
1) Disconnect the connector from blower
motor.
2) Connect the battery positive (+) terminal to
terminal No. 1 of blower motor connector, and
negative (−) terminal to terminal No. 2 and No.
5.
3) Make sure the blower motor runs.Does the blower motor run? Go to step 5.Replace the
blower motor.
5 CHECK POOR CONTACT.
Check poor contact in auto A/C control module
connector.Is there poor contact in con-
nector?Repair the con-
nector.Replace the auto
A/C control mod-
ule.

AC-18
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostics for A/C System Malfunction
Step Check Yes No
1 CHECK FUSE.
1) Turn the ignition switch to OFF.
2) Remove the main fan fuse and sub fan fuse
in main fuse box.
3) Check the condition of fuse.Is the fuse blown out? Replace the fuse. Go to step 2.
2 CHECK THE POWER SUPPLY TO PRES-
SURE SWITCH.
1) Disconnect the connector from pressure
switch.
2) Turn the ignition switch to ON.
3) Measure the voltage between harness con-
nector and chassis ground.
Connector & terminal
(F79) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 3.Repair the har-
ness for pressure
switch power sup-
ply circuit.
3 CHECK THE HARNESS BETWEEN PRES-
SURE SWITCH AND A/C RELAY HARNESS.
1) Turn the ignition switch to OFF.
2) Remove the A/C relay in the main fuse box.
3) Measure the resistance between A/C relay
and pressure switch connector.
Connector & terminal
(F27) No. 17 — (F79) No. 2:Is the resistance less than 1
Ω?Go to step 4.Repair the har-
ness between A/C
relay and pres-
sure switch.
4 CHECK THE PRESSURE SWITCH.
Measure the resistance between pressure
switch terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance less than 1
Ω?Go to step 5.Replace the pres-
sure switch.
5 CHECK THE A/C CUT SIGNAL CIRCUIT.
1) Disconnect the connector from auto A/C
control module.
2) Measure the resistance between auto A/C
control module and pressure switch connector.
Connector & terminal
(i48) No. 10 — (F79) No. 2:Is the resistance less than 1
Ω?Go to step 6.Repair the har-
ness between auto
A/C control mod-
ule and pressure
switch.
6 CHECK THE A/C ON SIGNAL CIRCUIT.
1) Disconnect the connector from ECM.
2) Measure the resistance between ECM and
auto A/C control module connector.
Connector & terminal
Turbo model
(B137) No. 17 — (i49) No. 17:
Non-turbo model
(B136) No. 11 — (i49) No. 17:Is the resistance less than 1
Ω?Go to step 7.Repair the har-
ness between auto
A/C control mod-
ule and ECM.
7 CHECK A/C RELAY.
1) Remove the A/C relay in main fuse box.
2) Check the A/C relay. INSPECTION, Relay and Fuse.>Is the operation of the relay
OK?Go to step 8.Replace the A/C
relay.
8 CHECK POWER SUPPLY TO MAGNET
CLUTCH OF A/C COMPRESSOR.
1) Turn the ignition switch to OFF, and then
connect the A/C relay connector and all
removed connectors.
2) Start the engine, and turn A/C switch to
ON.
3) Set the temperature control dial to maxi-
mum cold position.
4) Measure the voltage between magnet
clutch harness connector and chassis ground.
Connector & terminal
(F24) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10.5 V
(at normal temperature)?Go to step 9.Repair the har-
ness for power
supply line of A/C
compressor.

AC-19
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostics for A/C System Malfunction
9 CHECK OPERATION OF MAIN FAN MOTOR.
1) Start the engine and turn the A/C switch to
ON.
2) Check the operation of main fan motor.Does the main fan motor oper-
ate normally?Go to step 14.Go to step 10.
10 CHECK POWER SUPPLY TO MAIN FAN MO-
TOR.
CAUTION:
Be careful not to overheat the engine during
repair.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from main fan
motor.
3) Start the engine, and warm it up until
engine coolant temperature increases over
100°C (212°F).
4) Stop the engine and turn ignition switch to
ON.
5) Measure the voltage between main fan
motor harness connector and chassis ground.
Connector & terminal
Except turbo AT model:
(F17) No. 2 (+) — Chassis ground (
−):
Turbo AT model:
(F17) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 11.Repair the har-
ness for main fan
motor power sup-
ply circuit.
11 CHECK GROUND CIRCUIT OF MAIN FAN
MOTOR.
Measure the resistance between main fan
motor harness connector and chassis ground.
Connector & terminal
Except turbo AT model:
(F17) No. 1 — Chassis ground:
Turbo AT model:
(F17) No. 2 — Chassis ground:Is the resistance less than 1
Ω?Go to step 12.Repair the har-
ness for main fan
motor ground cir-
cuit.
12 CHECK MAIN FAN MOTOR.
Connect the battery positive (+) terminal to ter-
minal No. 2, and ground (−) terminal to termi-
nal No. 1 of main fan motor connector to make
sure that main fan motor rotate.Does the main fan rotate? Go to step 13.Replace the main
fan motor.
13 CHECK POOR CONTACT IN MAIN FAN MO-
TOR CONNECTOR.
Check poor contact in main fan motor harness
connector.Is there poor contact in con-
nector?Go to step 14.Repair the poor
contact in main fan
motor connector.
14 CHECK OPERATION OF SUB FAN MOTOR.
1) Start the engine and turn the A/C switch to
ON.
2) Check the operation of sub fan motor.Does the sub fan motor oper-
ate normally?Go to step 19.Go to step 15. Step Check Yes No

AC-20
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostics for A/C System Malfunction
15 CHECK POWER SUPPLY TO SUB FAN MO-
TOR.
CAUTION:
Be careful not to overheat the engine during
repair.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from sub fan
motor.
3) Start the engine, and warm it up until
engine coolant temperature increases over
100°C (212°F).
4) Stop the engine and turn ignition switch to
ON.
5) Measure the voltage between sub fan
motor harness connector and chassis ground.
Connector & terminal
Except turbo AT model:
(F16) No. 2 (+) — Chassis ground (
−):
Turbo AT model:
(F16) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 16.Repair the har-
ness for sub fan
motor power sup-
ply circuit.
16 CHECK GROUND CIRCUIT OF SUB FAN
MOTOR.
Measure the resistance between sub fan motor
harness connector and chassis ground.
Connector & terminal
Except turbo AT model:
(F16) No. 1 — Chassis ground:
Turbo AT model:
(F16) No. 2 — Chassis ground:Is the resistance less than 1
Ω?Go to step 17.Repair the har-
ness for sub fan
motor ground cir-
cuit.
17 CHECK SUB FAN MOTOR.
Connect the battery positive (+) terminal to ter-
minal No. 2, and ground (−) terminal to termi-
nal No. 1 of sub fan motor connector to make
sure that sub fan motor rotate.Does the sub fan motor rotate? Go to step 18.Replace the sub
fan motor.
18 CHECK POOR CONTACT IN SUB FAN MO-
TOR CONNECTOR.
Check poor contact in sub fan motor connec-
tor.Is there poor contact in con-
nector?Go to step 19.Repair the poor
contact in sub fan
motor connector.
19 CHECK POOR CONTACT IN AUTO A/C
CONTROL MODULE CONNECTOR.
Check poor contact in auto A/C control module
connector.Is there poor contact in con-
nector?Replace the auto
A/C control mod-
ule.Repair the con-
nector. Step Check Yes No

AC-22
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Procedure for Actuators
Step Check Yes No
1 CHECK POWER SUPPLY FOR INTAKE
DOOR ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the intake door actuator con-
nector.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake door
actuator connector and chassis ground.
Connector & terminal
(B91) No. 4 (+) — Chassis ground (
−):Is the voltage 7 V (at normal
temperature)?Go to step 2.Check open or
short circuit in har-
ness between
intake door actua-
tor and fuse.
2 CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND INTAKE DOOR
ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the auto A/C control module
connector.
3) Measure the resistance between intake
door actuator connector and auto A/C control
module connector.
Connector & terminal
LHD model:
(i49) No. 18 — (B91) No. 2:
(i49) No. 19 — (B91) No. 3:
(i49) No. 20 — (B91) No. 1:
RHD model:
(i49) No. 18 — (B91) No. 1:
(i49) No. 19 — (B91) No. 3:
(i49) No. 20 — (B91) No. 2:Is the resistance less than 1
Ω?Go to step 3.Repair the har-
ness between auto
A/C control mod-
ule and intake
door actuator.
3 CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Connect the intake door actuator connec-
tor.
2) Ground the auto A/C control module con-
nector with a suitable wire.
3) Turn the ignition switch to ON, and check
the operation of intake door actuator.
Connector & terminal
(i49) No. 20 — Chassis ground:Does the actuator move to
FRESH side?Go to step 4.Replace the intake
door actuator.
4 CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Turn the ignition switch to OFF.
2) Ground the auto A/C control module con-
nector with a suitable wire.
3) Turn the ignition switch to ON, and check
the operation of intake door actuator.
Connector & terminal:
(i49) No. 18 — Chassis ground:Does the actuator move to
RECIRC side?Replace the auto
A/C control mod-
ule.Replace the intake
door actuator.

AC-24
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Procedure for Actuators
Step Check Yes No
1 CHECK POWER SUPPLY FOR AUTO A/C
CONTROL MODULE SIDE.
1) Turn the ignition switch to ON.
2) Turn the mode control dial to VENT posi-
tion.
3) Press the defroster switch and measure the
voltage between auto A/C control module and
chassis ground when VENT is changed to DEF
position.
Connector & terminal
(i49) No. 9 (+) — Chassis ground (
−):Is the voltage more than 12 V? Go to step 2.Replace the auto
A/C control mod-
ule.
2 CHECK POWER SUPPLY FOR ACTUATOR
SIDE.
1) Turn the mode control dial to VENT posi-
tion.
2) Press the defroster switch and measure the
voltage between mode door actuator harness
connector and chassis ground when VENT is
changed to DEF position.
Connector & terminal
(B77) No. 1 (+) — Chassis ground (
−):Is the voltage more than 7 V (at
normal temperature)?Go to step 3.Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.
3 CHECK POWER SUPPLY FOR AUTO A/C
CONTROL MODULE SIDE.
1) Press the defroster switch.
2) Turn the mode control dial to VENT position
and measure the voltage between auto A/C
control module and chassis ground when DEF
is changed to VENT position.
Connector & terminal
(i49) No. 8 (+) — Chassis ground (
−):Is the voltage more than 12 V? Go to step 4.Replace the auto
A/C control mod-
ule.
4 CHECK POWER SUPPLY FOR ACTUATOR
SIDE.
1) Press the defroster switch.
2) Turn the mode control dial to VENT position
and measure the voltage between mode door
actuator harness connector and chassis
ground when DEF is changed to VENT posi-
tion.
Connector & terminal
(B77) No. 2 (+) — Chassis ground (
−):Is the voltage more than 7 V (at
normal temperature)?Go to step 5.Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.
5 CHECK ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mode door
actuator.
3) Connect the battery positive (+) terminal to
terminal No. 1 and ground (−) terminal to termi-
nal No. 2 of mode door actuator to make sure
that actuator operates.
4) Connect the battery positive (+) terminal to
terminal No. 2 and ground (−) terminal to termi-
nal No. 1 of mode door actuator to make sure
that actuator operates.Does the motor operate nor-
mally?Go to step 6.Replace the mode
door actuator.

AC-25
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Procedure for Actuators
6 CHECK AUTO A/C CONTROL MODULE SIG-
NAL VOLTAGE.
1) Turn the ignition switch to ON.
2) Turn the mode control dial and measure
voltage between auto A/C control module har-
ness connector and chassis ground for each
mode.
Connector & terminal
(i48) No. 4 (+) — Chassis ground (
−):Is the voltage 5 V when HEAT,
D/H, DEF position and 0 V
when VENT, BI-LEVEL posi-
tion?Go to step 9.Go to step 7.
7 CHECK AUTO A/C CONTROL MODULE SIG-
NAL POWER SUPPLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mode door
actuator.
3) Turn the ignition switch to ON.
4) Measure the voltage between mode door
actuator harness connector and chassis
ground.
Connector & terminal
(B77) No. 5 (+) — Chassis ground (
−):Is the voltage 5 V? Go to step 9.Go to step 8.
8 CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND MODE DOOR AC-
TUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from auto A/C
control module and mode door actuator.
3) Measure the resistance of harness
between auto A/C control module and mode
door actuator.
Connector & terminal
(i48) No. 4 (+) — (B77) No. 5 (
−):Is the resistance less than 1
Ω?Replace the auto
A/C control mod-
ule.Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.
9 CHECK AUTO A/C CONTROL MODULE SIG-
NAL VOLTAGE.
1) Turn ignition switch to ON.
2) Turn the mode control dial and measure
voltage between auto A/C control module har-
ness connector and chassis ground for each
mode.
Connector & terminal
(i48) No. 12 (+) — Chassis ground (
−):Is the voltage 5 V when VENT,
D/H position and 0 V when BI-
LEVEL, HEAT, DEF position?Go to step 12.Go to step 10.
10 CHECK AUTO A/C CONTROL MODULE SIG-
NAL POWER SUPPLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mode door
actuator.
3) Turn the ignition switch to ON.
4) Measure the voltage between mode door
actuator harness connector and chassis
ground.
Connector & terminal
(B77) No. 6, 9 (+) — Chassis ground (
−):Is the voltage 5 V? Go to step 12.Go to step 11. Step Check Yes No

AC-26
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Procedure for Actuators
11 CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND MODE DOOR AC-
TUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from auto A/C
control module and mode door actuator.
3) Measure the resistance of harness
between auto A/C control module and mode
door actuator.
Connector & terminal
(i48) No. 12 — (B77) No. 6, 9:Is the resistance less than 1
Ω?Replace the auto
A/C control mod-
ule.Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.
12 CHECK AUTO A/C CONTROL MODULE SIG-
NAL VOLTAGE.
1) Turn ignition switch to ON.
2) Turn the mode control dial and measure
voltage between auto A/C control module har-
ness connector and chassis ground for each
mode.
Connector & terminal
(i48) No. 5 (+) — Chassis ground (
−):Is the voltage 5 V when BI-
LEVEL, DEF position and 0 V
when VENT, HEAT, D/H posi-
tion?Go to step 15.Go to step 13.
13 CHECK AUTO A/C CONTROL MODULE SIG-
NAL POWER SUPPLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mode door
actuator.
3) Turn the ignition switch to ON.
4) Measure the voltage between mode door
actuator harness connector and chassis
ground.
Connector & terminal
(B77) No. 4, 7 (+) — Chassis ground (
−):Is the voltage 5 V? Go to step 15.Go to step 14.
14 CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND MODE DOOR AC-
TUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from auto A/C
control module and mode door actuator.
3) Measure the resistance of harness
between auto A/C control module and mode
door actuator.
Connector & terminal
(i48) No. 5 — (B77) No. 4, 7:Is the resistance less than 1
Ω?Replace the auto
A/C control mod-
ule.Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.
15 CHECK AUTO A/C CONTROL MODULE SIG-
NAL VOLTAGE.
1) Turn ignition switch to ON.
2) Turn the mode control dial and measure
voltage between auto A/C control module har-
ness connector and chassis ground for each
mode.
Connector & terminal
(i48) No. 13 (+) — Chassis ground (
−):Is the voltage 5 V when VENT,
BI-LEVEL, HEAT position and
0 V when D/H, DEF position?Go to step 19.Go to step 16. Step Check Yes No