1991 MITSUBISHI 3000GT Service Manual

FULL AUTO AIR CONDITIONER - Troubleshootinn55-47
3. Inspection of compartment-temperature sensor, outside-air-temperature sensor, and air therm0
sensor circuits
Air conditioner
compressor relay
Air conditioner control
unitA~rconditlonercompiessor
command arllhmew ctrcutc#
Sensorpowersource
Controlled variableIControlled variable
-IIIA/D conversion
Compartment
temperaruresensor
Finsensor
?J
Outside air
temperature
sensor2OFOO60
Troubleshooting Hintsl Diagnosis
No. 11, 12 [Fix compartment temperature sensor input signal at 25°C (77°F).
No. 13, 14 [Fix outside-air-temperature sensor input signal at 15°C
(59”Fj.INo. 21, 22 [Fix fin
therm0 sensor input signal at -2°C (-35.6”FJ.ll Air conditioner control unit terminal voltages
Terminal No.Signal nameConditionTerminal voltage
5Outside-air-temperature sensorTemperature at sensor 25°C (77°F) (4 klR)2.2 - 2.8 V
10Sensor power sourceNormally4.8 - 5.2 V
16Compartment temperatureTemperature at sensor 25°C (77°F) (4 klR)2.3 - 2.9 V
sensor
17Fin therm0 sensorTemperature at sensor 25°C (77°F) (4 k0)2.3 - 2.9 Vwhen air conditioner is OFF
TSB Revision

55-48FULL AUTO AIR CONDITIONER - Troubleshooting
[4. Inspection of water-temperature sensor and photo sensor circuits (
Air conditionercontrol panel
A
{ f*)- Potentiometer
‘>/b Damper drive
motor
\/\,9 Air conditioner
a 7 control unit
Water
temperature
sensor
m

Air conditionerEach sensorcontrol unit&
Air control panel
I.L .Solar radmtmnFin speed arlth-compensating ClrC”itmetIC ClrCUlt#t
A/D convertionND convemon
J2010043
I-
Troubleshooting Hintsl Air conditioner control unit terminal voltages
Terminal No.Signal nameConditionTerminal voltage
19Photo sensor 0llluminance 100,000 lux or more-0.1 to -0.2 v
llluminance less than 0 Iuxov
20Photo sensor 0Normallyov
9Water-temperature sensor 0Switch OFF [Engine coolant temperature
less than 50°C (122”F)]
Battery voltage
Switch ON [Engine coolant temperature
0 V
50°C (122°F) or higher]
1 TSB Revision

FULL AUTO AIR CONDITIONER - Troubleshooting55-495. Inspection of belt lock controller circuit
Compressor relay
tAir conditioner control unitAir conditioner
+control panelAir
condltloner,c.compressor commandAH condmonerarithmetic
circuitcompressor ONstgnal
ComparatorAir condltlonercompressor ON signal20 FOO58
Revolution pickup sensor
LiTroubleshooting Hintsl Air conditioner control unit terminal voltages
Terminal No.
Signal nameConditionTerminal voltage
11Air conditioner outputCompressor ONIO V to battery voltage
TSB Revision

55-50FULL AUTO AIR CONDITIONER - Troubleshooting
6.Inspection of air mix damper, outlet selector damper, inside/outside-air selector damper drive
motor circuits
Air conditioner
Air conditioner control panelcontrol panel
/hOutsideair
f:nsor
Damper
drive motor
\\
” 6

Air conditioner control unit
Poten-tiomet
20N0048
Air conditioner
control panel
23
20N0099
1 TSB Revision

FULL AUTO AIR CONDITIONER - Troubleshooting55-51
L
iv
i
Air conditioner
Air conditioner control unith control panel
ComparatorInsideloutslde atrcontrol ClrCUlt
Ezz3
Inside/outside air selector12 damper drive motor
Troubleshooting Hintsl Air conditioner control unit terminal voltages
Terminal No.
22
23
24
25
31
32
20NO098
Signal name
Inside/outside-air selector
damper drive motor
0
ConditionTerminal voltage
Inside-air switch ON
0.5 v(Output turns OFF 40 seconds after the damper
moved to inside air position.)
Outside-air switch ON
1ov(Output turns OFF 40 seconds after the damper
moved to outside air position.)$ot~kt~lector
damper driveFACE switch ON0.5 v
(Output turns OFF 40 seconds after the damper
moved to FACE position.)
DEF. switch ON
1ov(Output turns OFF 40 seconds after the dampermoved to DEF. position.)
Inside/outside-air selector
damper drive motor 0Inside-air switch ON
(Output turns OFF 40 seconds after inside air
has been activated.)IOV
Outside-air switch ON0.5v(Output turns OFF 40 seconds after outside air
has been activated.)
Air mix damper drive motor 0Temperature is set at 17°C (62.6”F).0.5v(Output turns OFF 40 seconds after the damper
moved to MAX. COOL position.)
Temperature is set at
32.5”C (90.5”F).1ov(Output turns OFF’40 seconds after the damper
moved to MAX. HOT position.)
Air mix damper drive motor
0Temperature is set at 17°C (62.6”F).IOV(Output turns OFF 40 seconds after the damper
moved to MAX. COOL position.)
Temperature is set at
32.5”C (90.5”F).0.5v(Output turns OFF 40 seconds after the damper
moved to MAX. HOT position.)
PO;:; Elector damper driveFACE switch ONIOV(Output turns OFF 40 seconds after the dampermoved to FACE position.)
DEF. switch ON
0.5 v
(Output turns OFF 40 seconds after the damper
moved to DEF. position.)
TSB Revision

55-52FULL AUTO AIR CONDITIONER - Troubleshooting
7. Inspection of power transistor and blower motor relay circuitsllower
Potor t?lay
El12
3 4
Ignitionswitch IG2Blower motor
relay
Air conditioner
-control panel
IWY/\2’
a.T
Air conditioner control unit
Fan speed anth-mete circw
)lardiatlon‘nsor2OFOO59
Troubleshooting Hintsl Air conditioner control unit terminal voltages
Power transistor baseTSB Revision

FULL AUTO AIR CONDITIONER - Troubleshootina55-53r
---.__------
2OFOO8:
SELF-DIAGNOSIS CHECKING
Self-diagnosis checking is performed when there has been anautomatic cancellation, without cancel switch operation.
The following method can be used for checking the diagnosis.
Note that the diagnosis check connector is located under the
driver’s side instrument panel.When multi-use tester is used
(1) Read and record the self-diagnosis outputs.
(2) Repair the faulty spots by referring to diagnosis chart.
(3) Erase the failure code.(4) Check the system again.
When voltmeter is used
(1) Connect an analog voltmeter across the self-diagnosis
output terminal @ and ground terminal @ of the diagnosis
connector.(2) Turn ON the ignition switch.
(3) According to the voltmeter pointer deflection, read the
self-diagnosis pattern.(4) Referring to the diagnosis chart, repair the faulty spot.
(5) Erase the failure code by the following procedure.
@ Turn OFF the ignition switch.
@ Disconnect the battery cable from a battery terminal
and leave it disconnected for 10 seconds or more; then,
reconnect the cable.
@ Turn ON the ignition switch and read the self-diagnosiscode to check that the correct code is being output.
1 TSB Revision

SERVICE DATA
ternno.Inspection
point
MethodCriteria
Probable cause
Normal
AbnormalRemedy11 Room-temper- Measure resistance of
sensor when room tem- ature sensorperature is 25°C (77°F).
Approx. 4 kS1Largely devrates
from approx.Defective room-tempera-
Replace room-tempera-
ture sensor
ture sensor.4
kll
Measure voltage across
In approx.
terminal @I of airOpen-circuited harness
Correct harness.2.3-2.9v-conditioner control unitbetween room-temperaturerange
sensor and air condrtionerand ground when room
control unittemperature is 25°C (77°F).Outside approx.
Poor connection of air
Correct connector-2.3-2.9vconditioner control unit
connection or replace’rangeconnector or defective air
air conditioner control
conditioner control unitunit.13
Outside-air-
Measure resistance of
Approx. 4 kllLargely deviates
Defective outside-air
Replace outside-air-temperaturesensor when ambient tem-
from approx. 4 kf2sensor
temperature sensor.
sensorperature is 25°C (77°F).
Measure voltage acrossIn approx.terminal @of air controlOpen-crrcuited harnessCorrect harness.2.2-2.8V-between outside-air-
conditioner unrt and
range
temperature sensor and
ground when ambient
air conditioner control unit
temperature is 25°C (77°F).Outside approx.Poor connection of air-
Correct connector-2.2-2.8Vconditioner control unit
connection or replacerangeconnector or defectiveair conditioner control
air conditioner control unitunit.15 Water-temper- Measure resistance of
ConductiveNonconductiveDefective water-
Replace water-
ature sensor
sensor when watertemperature sensor
temperature sensor.
temperature is 22.5 to
30.5”C (57.6 to 86.9”F).21 Air therm0
sensorMeasure voltage acrossApprox. 12 V
Open-circuited harness
Correct harness.terminal @ of air condi--between water-temperaturetioner control unit and
sensor and air conditioner
ground when water tempera-
control unit
ture is 22.5 to 30.5”C(57.6 to 86.9”F).Largely deviatesPoor connection of airCorrect connector-from approx. 12 Vconditioner control unitconnection or replace
connector or defectiveair conditioner control
air conditioner control unitunit.
Measure resistance of
sen-Approx. 4 kS2Largely deviatesDefective air therm0Replace air therm0
sor when sensor’s sensing
from approx. 4 kb2sensorsensor.temperature is 25°C (77°F).
Measure voltage acrossIn approx.Open-circuited harness be-Correct harness.termrnal 0 of air conditioner2.3 - 2.9 V-tween air therm0 sensor and
control unit and groundrangeair conditioner control unit
when sensor’s sensing
temperature is 25°C (77°F).Outside approx.
Poor connection of airCorrect connector2.3-2.9vconditioner control unitconnection or replace
rangeconnector or defectiveair conditioner control
air conditioner control unit
unit.31 Air
mrx
Refer to P. 55-59.Defective air mix damperReplace air mix damper
damperpotentiometerpotentiometer.
potentiometer
-Measure voltage acrossIn approx.
Open-circuited harnessCorrect harness.
terminal @of airO.l-0.3v-between air mrx damper
conditioner control unitrangepotentiometer and arrand ground when potentio-conditioner control unrtmeter is in MAX. COOL
position.Outside approx.Poor connection of airCorrect connector
-0.1 -0.3vconditioner control unitconnection or replace
rangeconnector or defectiveair conditioner control
air conditioner control unitunit.33 Outlet
Refer to P. 55-59.Defective outlet selectorReplace outlet selector
selectordamper potentiometerdamper potentiometer.
damperpotentiometer
Measure voltage acrossIn approx.Open-circuited harnessCorrect harness.terminal @of air0.1 -0.3v-between outlet selectorconditioner control unitrangedamper potentiometerand ground when potentio-and air conditioner control
meter is in FACE position._Outside approx.Poor connection of airCorrect connector-0.1 -0.3vconditioner control unitconnection or replace
rangeconnector or defectiveair conditioner control
air conditioner control unit
unit.FULL AUTO AIR CONDITIONER
- Troubleskootina
1 TSB Revision