1991 MITSUBISHI 3000GT Service Manual

COOLING - Specifications / Troubleshooting
SEALANT AND ADHESIVE14-3
MMCE- -
/
id
ItemsSpecified sealants and adhesive/
Engine coolant temperature gauge unit
Engine coolant temperature sensor (Engine control)
Engine coolant temperature sensor (Air conditioner)3M Nut Locking Part No. 4171
TROUBLESHOOTING
L
MllEAAL
Symptom
OverheatProbable cause
Insufficient engine coolant
Too high an anti-freeze concentration
Inoperative electric cooling fan
Faulty thermosensor
Faulty electrical motor
Faulty radiator fan relayRemedy
Replenish
Correct anti-freeze concentration
Replace
Damaged or blocked (insufficiently ventilated)
radiator finsCorrect
Water leaks
Damaged radiator core joint
Corroded or cracked hoses
(radiator hose, heater hose, etc.)
Faulty cap valve or setting of spring
Cracked thermostat housing
Loose water pump mounting bolt or leaking
gasket
Replace
Loose bolt or leaking gasket in water outlet
I
Correct or replacefitting
Loose bolt or leaking gasket in water inletfitting
Loose thermostat housing bolts or leakingfrom gasket
Retorque bolts or replace gasket
Faulty automatic transaxle oil cooler operation
Blocked or collapsed hose and pipeReplace
Loose hose and pipe connectionCorrect
Faulty thermostat operationReplace
Faulty water pump operationReplace
Water passage clogged with slime or rust depositClean
or foreign substance
No rise in temperature
Faulty thermostatReplace
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14-4COOLING - Troubleshooting
CIRCUIT DIAGRAM
FUSIBL
RADIATOR
FAN ASSEMBLY
(RADIATOR
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FAN MOTOR>r{
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IGNITION
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RADIATOR FAN ASSEMBLYL!a ml
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X35-AC-NWOl-NY
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COOLING - Troubleshootina14-5
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FUSIBLELINK@
_------ __._ -_--
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AIR CONDITIONER
COMPRESSOR LOCK
CONTROLLERRADIATOR
FAN MOTOR
RELAYCLO)
A-36
A-45
@!A
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14-6COOLING - Troubleshooting.TROUBLESHOOTING HINTS
1. Neither the radiator fan nor condenser fan
rotate at all.
l Check fusible link No. 5.
2. Only the condenser fan does not operate.
l Check dedicated fuse No. 8.
3. The radiator fan and condenser fan do not
operate in the low speed mode, but operate
otherwise.
(1) The A/C compressor magnet clutch does not
enter the “ON” state.
l Check whether the output of the auto
compressor control unit is available.
NOTEFor troubleshooting of the air conditioner
control unit, refer to GROUP 55.
(2) The A/C compressor magnet clutch enters
the “ON” state.
l Check the resistor.
Fan Operating Model Check the radiator fan motor relay (LO)
and condenser fan motor relay (LO).
l Check the therm0 sensor (for radiator
fan).
(3) The radiator fan does not rotate when the ailconditioner switch is turned ON.
l Check the radiator fan motor control
relay.4. The radiator fan and condenser fan do not
operate in the high speed mode, but operate
otherwise.l Check the therm0 sensor (for condenser
fan).
lCheck the radiator fan motor relay (HI) and
condenser fan motor relay (HI).Air
conditionerswitch
Switch conditionsTherm0 sensor
For radiator fan
For condenser fan
ON at 85
k 4°C
ON at 95 t 4°C
(185 f 7°F) or more(203 + 7°F) or more
OFF at 77°C (171°F)
OFF at 87°C (189°F)or less
or lessEngine coolant
temperature switch
(for air conditioner
cut-off) OFF at 115
+3°C (239 2 5°F) or
over, ON at 108°C
(226°F) or lessFan revolving operation
conditionCondenser fan motor
Condenser fan motorRadiator fan motor
operates
In HIGH only
when it receives input
from condenser fan
motor relay (HI) and
U-0).I/I/
OFF
OFF
OFFOFF
IOFFIOFF
ONLOWOFF
ON
HIGHLOW
OFF
OFFLOWLOW
OFF
ONON
LOWLOW
ON
HIGH
ONHIGH
OFF
HIGHLOW
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COOLING - Service Adiustment Procedures.14-7
SERVICE ADJUSTMENT PROCEDURES
ENGINE COOLANT LEAK CHECKMl4FAAF
1. Loosen cap.
2.Confirm that the engine coolant level is up to the filler neck.
3.Install an adapter to the water outlet fitting and apply 160
kPa (23 psi) pressure. Hold pressure for two minutes, while
checking for leakage from the radiator, hose or connec-
tions.
CautionBe sure to completely clean away any moisture from
the places checked.
When the tester is removed, be careful not to spill anyengine coolant from it.
Be careful, when installing and removing the tester andwhen testing, not to deform the water outlet fitting.
4. If there is leakage, repair or replace the appropriate part.
CAP PRESSURE TESTM14FBAH1. Use a special tool to attach the cap to the tester.
2.Increase the pressure until the indicator of the gauge stops
moving.
Limit: 65
kPa (9.2 psi)
Standard value: 75
- 105 kPa (11 - 15 psi)
3:Replace the cap if the reading does not remain at or above
the limit.
NOTEBe sure that the cap is clean before testing, since rust or
other foreign material on the cap seal will cause an
improper indication.
ENGINE COOLANT REPLACEMENTM14FCAGRefer to GROUP 00
- Maintenance Service.
ENGINE COOLANT CONCENTRATION TEST
M14FDALRefer to GROUP 00
- Selection of Coolant.
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14-8COOLING - Radiator
RADIATOR
REMOVAL AND INSTALLATIONM14QA..
Removal steps of radiator
1. Drain plug2. Cap3. Overflow tube
4. Water level sensor connector
5. Reserve tank
6. Radiator upper hose
7. Radiator lower hose
8. Automatic transaxle oil cooler hoses
9. Condenser fan motor connector
10. Condenser fan motor assembly

** 11. Radiator fan motor connector
12. Connection of therm0 sensor(For radiator fan)13. Connection of therm0 sensor(For condenser fan)
14. Radiator fan motor assembly
15. Upper insulator
16. Radiator assembly
17. Lower insulator
Removal steps of radiator fan motor assembly
1. Drain plug2. Cap
6. Radiator upper hose
9. Condenser fan motor connector

10. Condenser fan motor assembly

l * 11. Radiator fan motor connector12. Connection of therm0 sensor(For radiator fan)13. Connection of therm0 sensor
18.
Therm0 sensor (For radiator fan)
19. Therm0 sensor (For condenser fan)
(For condenser fan)
20. Fan
14. Radiator fan motor assembly20. Fan
21. Radiator fan motor21. Radiator fan motor
22. Resistor22. Resistor
23. Shroud23. Shroud
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COOLING - Radiator14-S
- 04N0002
SERVICE POINT OF REMOVALM14QBAK8. DISCONNECTION OF AUTOMATIC TRANSAXLE OIL
COOLER HOSESUse a plug or otherwise cover the hose and nipple part of
the radiator so that dust, dirt, foreign materials, etc. do not
enter after the hose has been disconnected from the
radiator.
INSPECTIONM14QCAN
l Check for foreign material between radiator fins.
l Check the radiator fins for bent, or damage.
l Check the radiator for corrosion, damage rust or scale.
lCheck the radiator hoses for cracks, damage or deteriora-
tion.
l Check the reserve tank for damage.
lCheck the automatic transaxle oil cooler hoses for cracking,
damage or deterioration.
RADIATOR FAN MOTOR INSPECTION
(1) Check to be sure that the radiator fan rotates when battery
voltage is applied between terminals (as shown in the
figure).(2) Check to see that abnormal noises are not produced, while
motor is turning.
INSPECTION OF RESISTOR(1) Measure the resistance between connector terminals @
and @ of the radiator fan motor.
(2) The resistor is normal if the resistance is within the
following range.
Resistance: 0.29
- 0.35 IZ
THERM0 SENSOR INSPECTION
(1) Immerse the water temperature switch in hot water as
shown.
(2) Change the water temperature and check continuity with a
circuit tester.. If it is as specified below, the switch is
functioning correctly.
Item
With continuityb;F;;ature of
Without continuity
(t;,n-r3;rature ofFor condenser fanFor radiator fan91
- 99°C81 - 89°C(196 - 210°F)(178 - 192°F)87°C (189°F)
’77°C (I 71 “F)
or lessor less
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14-10COOLING - Radiator
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0312161908
Ionnector04FOOO8
RADIATOR FAN MOTOR RELAY INSPECTION
(1) Remove radiator fan motor relay from the relay box located
at the right side in the engine compartment.
Ll(2) Check for continuity between the terminals when the
battery power-supply is applied to terminal
0, and terminal@ is grounded.
When current
flowsBetweenterminals 1
- 3Continuity
When nocurrent flowsBetweenterminals 1 - 3No continuity
Betweenterminals 2 - 4Continuity
SERVICE POINT OF INSTALLATIONM14QDAH
11. CONNECTION OF RADIATOR FAN MOTOR CONNEC-
TORConnect the radiator fan motor connector to the body
harness. Then, insert into the shroud hole and fix securely.
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