2004 SUBARU FORESTER sensor

AC-3
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
General Description
2. General Description
A: CAUTION
1) Never connect the battery in reverse polarity.
Auto A/C control module may be destroyed instant-
ly.
2) Do not disconnect the battery terminals while the
engine is running.
A large counter electromotive force will be generat-
ed in the generator, and this voltage may damage
electronic parts such as auto A/C control module,
etc.
3) Before disconnecting the connectors of each
sensor and the auto A/C control module, be sure to
turn off the ignition switch.
Auto A/C control module may be damaged.
4) Every A/C-related part is a precision part. Do not
drop them.
5) Airbag system wiring harness is routed near the
A/C control panel (auto A/C control module) and
junction box.
CAUTION:
 For airbag system, yellow-colored wiring har-
ness and connectors are all used. Do not use
the electrical test equipment on these circuits.
 Be careful not to damage the airbag system
wiring harness when servicing the A/C control
panel (auto A/C control module) and junction
box.
B: INSPECTION
Before performing the diagnosis, check the follow-
ing items which might affect A/C system problems.
1. BATTERY
1) Measure battery voltage and specific gravity of
electrolyte.
Standard voltage: 12 V
Specific gravity: More than 1.260
2) Check the condition of the fuses for A/C system
power supply and other fuses.
3) Check the condition of harness and harness
connector connections.
2. ASPIRATOR HOSE
1) Turn the ignition switch to ON, and press the A/
C switch.
2) Turn the temperature control dial at maximum
hot position.
3) Press the defroster switch.
4) Turn the fan speed control dial to 4th position.5) Approach a strip of paper (b) in front of the in-ve-
hicle sensor suction port (a) located in the instru-
ment lower cover, and check that air is being
sucked into the port by seeing the paper moving to-
wards port.
NOTE:
Be careful not to let the paper get sucked into port.
6) If the paper does not move at all, remove the in-
strument panel lower cover MOVAL, Instrument Panel Assembly.> and check
for improper connection of the aspirator hose (a),
in-vehicle sensor and heater unit, and repair them if
necessary.
3. A/C LINE
Check the connection for A/C line (A) and lower
side high-pressure pipe.
4. CONTROL LINKAGE
1) Check the state of mode door linkage.
2) Check the state of air mix door linkage.
3) Check the state of intake door linkage.
AC-00094
(a)
(a)
(b)
AC-00065
(a)
AC-00096
(A)

AC-5
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Electrical Component Location
3. Electrical Component Location
A: LOCATION
1. ENGINE COMPARTMENT
(1) A/C compressor (3) Pressure switch (4) Ambient sensor
(2) A/C relay
AC-00097 (1)
(2)
(4)
(1)
(3)
(2)
(3)

AC-6
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Electrical Component Location
2. PASSENGER COMPARTMENT
(1) Mode door actuator (4) Intake door actuator (7) Air mix door actuator
(2) In-vehicle sensor (5) Blower motor
(3) Sunload sensor (6) Evaporator sensor
AC-00098
(1) (6)(4)
(5) (7)(7)(6)(5) (4) (3)
(1) (2)
(3)

AC-7
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Auto A/C Control Module I/O Signal
4. Auto A/C Control Module I/O Signal
A: ELECTRICAL SPECIFICATION
Terminal No. Content Measuring conditionSpecified
value
B9
Mode door actuator power supplyChanges outlet from VENT to DEF.
*2
B8 Changes outlet from DEF to VENT.
B7
Air mix door actuator power supplyChanges air mix door from COOL to HOT.
*1
B6 Changes air mix door from HOT to COOL.
B5 IGN power supply Ignition switch: ON Battery voltage
B4 Battery power supply Ignition switch: OFF, ACC, ON Battery voltage
B3 Sunload sensorIgnition switch: ON and under normal sunload
(without sunload: 5 V)3 V
B2 Evaporator sensor Ignition switch: ON 5 V or less
B1 Air mix door actuator P.B.R. signalAir mix door: COOL position 0.5 V
Air mix door: HOT position 4.5 V
B20
Intake door actuator signalAir inlet: FRESH (other positions: 12 V) 0 V
B19 Air inlet: MIX (other positions: 12 V) 0 V
B18 Air inlet: RECIRC (other positions: 12 V) 0 V
B17 A/C ON signal A/C: ON (A/C OFF: 0 V) 8 — 10 V
B16 Blower motor control *3 *3
B15 Blower fan ON signalWhen blower fan running (when blower fan not
running: 12 V)0 V
B13 Engine coolant temperature sensor When the engine coolant is at 49°C (120°F) 8.9 V
B12 In-vehicle sensor — —
B11 Ground When there is continuity to chassis ground 0 Ω
A7 Air mix door actuator P.B.R. reference voltage Ignition switch: ON 5 V
A5 Mode door actuator position detection signal OutletBI-LEVEL, DEF 5 V
VENT, HEAT, DEF/HEAT 0 V
A4 Mode door actuator position detection signal OutletHEAT, DEF/HEAT, DEF 5 V
VENT, BI-LEVEL 0 V
A1 Illumination power supplyIgnition switch: ON, light switch: ON Battery voltage
Ignition switch: ON, light switch: OFF 0 V
A16 Sensor ground When there is continuity to chassis ground 0 Ω
AC-00099
1 2 3 4 5 6 7 8 910
11 12 13 14 15 16 17 18 19 201 2 3 4 5 6 7 8
9
10 11 12 13 14 15 16
i48B: To A:To
i49

AC-9
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Chart for Self-Diagnosis
5. Diagnostic Chart for Self-Diagnosis
A: OPERATION
(1) Temperature control dial (4) A/C switch (7) Rear window defogger switch
(2) OFF/BRIGHT switch (5) Defroster switch (8) FRESH/RECIRC switch
(3) AUTO switch (6) Air flow control switch (9) Fan speed control dial
(1) Normal Operation (6) After the LED display (Approx. 20
sec.)(9) Output Equipment Operation
(Sequential Operation)
(2) Switch
(3) IG OFF → ON with pressing (7) Sensor Check (Sequential Opera-
tion)(10) Output Equipment Operation
(Phased Operation)
(4) Self-Diagnosis Mode
(5) LED Display Check (8) Sensor Check (Phased Operation)
AC-00250
(5)
(6)(7)
(8) (9) (4)
(3)
(2)
(1)
AC-00242
OFF
AUTO
AUTO
AUTO
AUTOAUTO
(5)(4) (3)
DEF A / C+
A / CA / C
A / C A / C
(6)
(7)
(8)(9)
(10)
FRESH / RECIRCFRESH / RECIRCFRESH / RECIRC
FRESH / RECIRC:
(2)
(1)

AC-10
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Chart for Self-Diagnosis
Step Check Yes No
1 SELECT CONTROL PANEL TO SELF-DIAG-
NOSIS MODE.
1) Turn the ignition switch to OFF.
2) Start the engine while pressing defroster
switch and A/C switch.
N
OTE:
Self-diagnosis can also be performed with the
ignition switch ON, but start the engine be-
cause telling the magnet clutch operation is dif-
ficult.
3) The LED in A/C control panel blinks.Does the self-diagnosis mode
operate?Go to step 2. C OR SELF-DIAG-
NOSIS SYS-
TEMS DO NOT
OPERATE, Diag-
nostics for A/C
System Malfunc-
tion.>
2 CHECK LED ILLUMINATION.
Make sure that three LED blink in turn on A/C
control panel (5 patterns are repeated 2 times).Do all LED blink? Go to step 3.Go to step 5.
3 CHECK SENSORS MALFUNCTION.
1) After completing the LED check or when
AUTO switch is pressed, the A/C switch LED
illuminates, and then the sensor check is
started.
2) Check the input signal of each sensor in
turn. If there are any trouble for each sensor,
DEF, MODE and fan speed LEDs are blinked.
Also check for each sensor is possible respec-
tively every time AUTO switch is pressed. (At
this time, the AUTO switch LED illuminates.)
3) If there is no trouble, DEF, MODE and fan
speed LEDs are turned off.
N
OTE:
Rear window defogger LED illuminates in case
of stored malfunction but does not illuminate in
case of present malfunction.Does each DEF, MODE and
fan speed LED turn off?Go to step 4.Confirm the com-
bination of illumi-
nating LEDs by
using Sensor
Check Table, and
identify the mal-
functioning sensor
before repairing.
SENSOR CHECK
TABLE, OPERA-
TION, Diagnostic
Chart for Self-
Diagnosis.>
4 CHECK OPERATION OF EACH ACTUATOR,
COMPRESSOR AND FAN MOTOR.
1) Press the FRESH/RECIRC switch
(FRESH/RECIRC switch LED illuminates at
this time.).
2) Refer to OPERATING MODE TABLE to
check the operation of each actuator, compres-
sor and fan motor. ING MODE TABLE, OPERATION, Diagnostic
Chart for Self-Diagnosis.>
Also check for each step is possible respec-
tively every time AUTO switch pressed. (At this
time, the AUTO switch LED illuminates.)Does each actuator, compres-
sor and fan motor operate
according to operating mode
table?Press the OFF
switch or turn the
ignition switch to
OFF and finish the
self-diagnosis
mode.Refer to each
diagnostics chart
for actuator, com-
pressor and fan
motor, and repair
the malfunctioning
par t as necessary.
Diagnostics for A/
C System Mal-
function.> AC-21, Diagnostic
Procedure for
Actuators.>
5 CHECK POOR CONTACT.
Check the auto A/C control module connector
for poor contact.Is there a poor contact in con-
nector?Replace the auto
A/C control mod-
ule.Repair the con-
nector.

AC-11
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Chart for Self-Diagnosis
1. SENSOR CHECK TABLE
NOTE:
When the sunload sensor is checked indoors or in the shade, open circuit might be indicated. Always check
the sunload sensor at a place where sun shines directly on it.
*1: Only present malfunction is indicated for open circuit of sunload sensor. (However, stored malfunction can be indicated for
short circuit of sunload sensor.)
2. OPERATING MODE TABLE
Diag-
nostic
stepsChecked sensorOpen circuit Short circuitPresent
malfunctionStored
malfunction
DEF LEDMODE/FAN
LEDDEF LEDMODE/FAN
LEDREAR WINDOW
DEFOGGER LED
1 In-vehicle sensor
Tu r n o f fVENT
LED blinks
IlluminateVENT
LED blinks
Turn off Illuminate 2 Ambient sensorBI-LEVEL
LED blinksBI-LEVEL
LED blinks
3 Evaporator sensorHEAT
LED blinksHEAT
LED blinks
4 Sunload sensor*1DEF/HEAT
LED blinksDEF/HEAT
LED blinks
5 Air mix door actuator P.B.R.Fan speed
1st
LED blinksFan speed
1st
LED blinks
6Combination meter commu-
nication (Ambient sensor)Fan speed
2nd
LED blinksFan speed
2nd
LED blinks
When all parts are in good condition Turn off
Step 12345678
Illuminating LEDVENT
LEDBI-LEVEL
VENTHEAT LEDDEF/HEAT
LEDFan speed
1st LEDFan speed
2nd LEDFan speed
3rd LEDFan speed
4th LED
Fan speed LO LO ML ML ML MH MH HI
Mode actuator VENT VENT VENT BI-LEVEL HEAT HEAT DEF/HEAT DEF
Intake actuator FRESH RECIRC RECIRC FRESH FRESH FRESH FRESH FRESH
Air mix door actuatorFULL
COOL
(0%)FULL
COOL
(0%)FULL
COOL
(0%)MEDIUM
(50%)MEDIUM
(50%)FULL HOT
(100%)FULL HOT
(100%)FULL HOT
(100%)
Compressor
(magnet clutch)OFFONONONONONONON

AC-32
HVAC SYSTEM (AUTO A/C)(DIAGNOSTIC)
Diagnostic Procedure for Sensors
8. Diagnostic Procedure for Sensors
A: AMBIENT SENSOR
TROUBLE SYMPTOM:
 Fan speed is not switched when the fan speed control dial is in AUTO position.
 Malfunction related to ambient sensor is indicated in self diagnosis.
WIRING DIAGRAM:
 LHD model
AC-00107
A:
i48B:
i49B:
i10
12345678
910 11 12 13 14 15 1612345678910
11 12 13 14 15 16 17 18 19 20
3
4 128910 11
12 13 14 15 16 17 18 19 20 21 22 23 24567
i41
B202
B202B38
i3
B38
B:
i10
COMBINATION
METER
A:
i48B:
i49
19
A14
24
B30
123456789101112131415161718192021222324252627282930
219
32
1234 5610 11 12 13 14 15716
23 3019 20
22 26 27 28 29817
24 3118
25
AUTO A/C
CONTROL
MODULE
i2
B37
141521
B24
B25
12
B62F45F78AMBIENT
SENSOR
B37
3
4 12
8910 11 12 13 14 15 16567
F45
12
F78