1991 MITSUBISHI 3000GT Service Manual

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HEATERS AND MANUAL AIR CONDITIONER -Service Adjustment Procedures 55 15
PERFORMANCE TESTM55FWAH
(I) Park the tested vehicle at the area which is not exposed to
the direct sunlight.
(2) Connect a tachometer.
(3) Turn back the adaptor valve handle all the way and install
the adaptor valves to the high pressure and low pressure
service valves.
(4) Connect the gauge manifold to the adaptor valves.
(5) Tighten the adaptor valve handle and open the service
valves.
(6) Start the engine.
(7) Set the controls to the air conditioner as follows:
Air conditioning switch: Air conditioner
- ON position
Mode selection: Face position
Temperature control: MAX. COOL position
Air selection: Recirculation position
Blower switch: HI (Fast) position
(8) Adjust engine speed to 1,000 rpm with air conditioner
clutch engaged.
(9) Engine should be warmed up with doors, windows close,
and hood open.
(1O)lnsert a thermometer in the center air conditioner outlet and
operate the engine for 20 minutes.
(II )Note the discharge air temperature.
NOTEIf the clutch cycles, take the reading before the clutch
disengages.
Performance Temperature ChartGarage
amb;in,L;am-perature21 (70)
26.7 (80)32.2 (90)37.8 (100)43.3 (110)
Iperature Dischargeair "C tem- ("F)(32.0 0.0- -3.0 37.4)(33.8 1.0- -4.0 39.2)(33.8 1.0- -4.0 39.2)(33.8 1.0- -4.0 39.2)(35.6 2.0- -41.0) 5.0
ICompressor pressure kPa discharge (psi)(98.1 690- -105.3) 740(110.9 780- -830 118.1)(123.7 870- -920 130.9)(153.6 1,080- -1,130 160.7)(172.1 1,210- -1,260 179.2)Compressor suction130
-190130-190130-190130-190130-190
pressure kPa (psi)(18.5-27.5)(18.5-27.5)(18.5-27.5)(18.5-27.5)(18.5-27.5)
REFRIGERANT LEAK REPAIR PROCEDUREM55FHAQ
LOST CHARGEIf the system has lost all charge due to a leak:
(1) Evacuate the system. (See procedure.)
(2) Charge the system with approximately one pound of
refrigerant.
(3) Check for leaks.
(4) Discharge the system.
(5) Repair leaks.
(6) Replace receiver drier.
Caution
Replacement filter-drier units must be sealed while instorage. The drier used in these units will saturate
water quickly upon exposure to the atmosphere. When
installing a drier, have all tools and supplies ready forquick reassembly to avoid keeping the system open
any longer than necessary.(7) Evacuate and charge the system.
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55-16 HEATERS AND MANUAL AIR CONDITIONER -Service Adjustment Procedures
LOW CHARGE~
If the system has not lost all of its refrigerant charge; locate and
repair all leaks. If it is necessary to increase the system
pressure to find the leak (because of an especially low charge)
‘iaadd of refrigerant. If it is oossible to reoair the leak without
discharging-the refrigerant system, use the procedure for
correcting low refrigerant level.
HANDLING TUBING AND FITTINGSM55FlAFKinks in the refrigerant tubing or sharp bends in the refrigerant
hose lines will greatly reduce the capacity of the entire system.
High pressures are produced in the system when it is
operating. Extreme care must be exercised to make sure that
all connections are pressure tight. Dirt and moisture can enter
the system when it is opened for repair or replacement of lines
or components. The following precautions must be observed.
The system must be completely discharged before opening
any fitting of connection in the refrigeration system. Open
fittings with caution even after the system has been dis-
charged. If any pressure is noticed as a fitting is loosened, allow
trapped pressure to bleed off very slowly.
Never attempt to rebend formed lines to fit. Use the correct
line for the installation you are servicing.
A good rule for the flexible hose lines is keep the radius of all
bends at least 10 times the diameter of the hose.
Sharper bends will reduce the flow of refrigerant. The flexible
hose lines should be routed so that they are at least 80 mm (3
in.) from the exhaust manifold. It is good practice to inspect all
flexible hose lines at least once a year to make sure they are in
good condition and properly routed.
\ Aj iUnified plumbing connections with O-rings. These O-rings are
-not reusable.
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COMPRESSOR NOISEM55FlAD
When investigating an air conditioning related noise, you must
first know the conditions when the noise occurs. These
conditions are: weather, vehicle speed, in gear on neutral,
engine temperature or any other special conditions.
Noises that develop during air conditioning operation can often
be misleading. For example: what sounds like a failed front
bearing or connecting rod. may be caused by loose bolts, nuts,
mounting brackets, or a loose clutch assembly. Verify acces-
sory drive belt tension (power steering or alternator).
Improper accessory drive belt tension can cause a misleading
noise when the compressor is engaged and little or no noise
when the compressor is disengaged.
Drive belts are speed sensitive. That is, at different engine
speeds, and depending upon belt tension, belts can develop
unusual noises that are often mistaken for mechanical prob-
lems within the compressor.
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HEATERS AND MANUAL AIR CbNDlTlONER -Service Adjustment Procedures 55 17
ADJUSTMENT PROCEDURES(1) Select a quiet area for testing. Duplicate conditions as much
as possible. Switch compressor on and off several times to
clearly identify compressor noise.
To duplicate high ambient conditions (high head pressure),
restrict air flow through condenser. Install manifold gauge
set to make sure discharge pressure doesn’t exceed 2,070
kPa (300 psi).
(2) Tighten all compressor mounting bolts, clutch mounting
bolt, and compressor drive belt. Check to assure clutch coil
is tight (no rotation or wobble).
(3) Check refrigerant hoses for rubbing or interference that can
cause unusual noises.
(4) Check refrigerant charge. (See “Charging System”.)
(5) Recheck compressor noise as in Step 1.
(6) If noise still exists, loosen compressor mounting bolts and
retorque. Repeat Step 1.
(7) If noise continues, replace compressor and repeat Step 1.
POWER RELAY CHECKMBBFNAK(1) Remove the radiator fan motor relays (HI) and (LO) from the
relay box on the right of the engine compartment.
(2) Remove the radiator fan motor relay (air conditioner),
condenser fan motor relays (HI) and (LO), and
air-conditioner compressor relay from the relay box on the left
of the engine compartment.
(3) Remove the blower motor relay from the junction box.
(4) Remove the blower motor HI relay from the blower case
assembly.
(5) Check the continuity between terminals using a circuit
tester.
J Blower m.otor HI relay\2OFOO6l
IDLE-UP OPERATION CHECKM55FOAB
(1) Before inspection and adjustment set vehicle in the
following condition:
lEngine coolant temperature: 80 - 95°C (176 - 203°F)
lLights, electric cooling fan and accessories: Set to OFF
l Transaxle: Neutral (N or P for vehicles with
A/T)l Steering wheel: Straightforward
(2) Check to be sure that the idling speed becomes the
standard value when the air conditioner switch is switched
ON and the air conditioner is activated.
Standard value: 900
+ 100 rpm
NOTEThere is no necessity to make an adjustment, because the
idling speed is automatically adjusted by the ISC” system.
If, however, there occurs a deviation from the standard
value for some reason, check the ISC” system.
ISC: Idle Speed Control
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55-I 8HEATERS AND MANUAL AIR CONDlTlONER - Heater Control Assembly
HEATER CONTROL ASSEMBLY
REMOVAL AND INSTALLATIONM55GA-A
Pre-removal and Post-installation Operationl Removal and installation of Floor Console
(Refer to GROUP 52A- Floor Console.)
Removal steps
1. Stopper2. Glove box outer case assembly**3. Connection of the air-selection control wire
4. Ho01 lock release handle
5. Rheostat assembly
6. Rear wiper &washer switch
7. Knee protector
8. Shower duct
l *9. Connection of the mode control wirel * 10. Connection of the temperature control wirea*11. Center air outlet assembly
12. Heater control assembly
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SERVICE POINT OF REMOVALM55GBAMl
11. REMOVAL OF CENTER AIR OUTLET ASSEMBLYDisengaging the clips (2 positions) of the center air outlet
assembly with a flat tip screwdriver, remove the center air
outlet assembly with the trim stick.
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HEATERS AND MANUAL AIR CONDITIONER - Heater cmrol *=mW55-19
20A040fINSPECTION
BLOWER SWITCH
M55GCAIOperate the switch, and check the continuity between the
terminals.
NOTEo-0 indicates that there is continuity between the terminals.
SERVICE POINTS OF INSTALLATIONM55GDAQ
10. INSTALLATION OF TEMPERATURE CONTROL WIREConnect the temperature control wire to the blend air
damper lever by following the steps below.
(1) Move the temperature control lever to the rightmost
position. (“HOT” position)
(2) With the blend air damper lever pressed completely
downward in the direction indicated by the arrow,
connect the inner cable of the temperature control wireto the end of the blend air damper lever, and then
secure the outer cable by using a clip.
9.INSTALLATION OF MODE SELECTION CONTROL WIREConnect the mode selection control wire to the mode
selection damper lever by following the steps below.
(1) Move the mode selection lever to the
$$ position.
(2) With the mode selection damper lever pressed inwardin the direction indicated by the arrow, connect the
inner cable of the mode selection control wire to the
end of the mode selection lever, and then secure the
outer cable by using a clip.
3.INSTALLATION OF AIR SELECTION CONTROL WIREConnect the air selection control wire to the air selection
damper lever by following the steps below.
(1) Move the air selection control lever to the &ZI position.
(2) With the air selection damper lever pressed inward in
the direction indicated by the arrow, connect the inner
cable of the air selection control wire to the end of the
air selection lever, and then secure the outer cable by
using a clip.TSB Revision

55-20 HEATERS AND MANUAL AIR CONDlTlONER - Resistor, Belt Lock Controller
RESISTOR, BELT LOCK CONTROLLERM55JA- -
REMOVAL AND INSTALLATION
viRemoval steps
1. Stoooer
2OFOO732. Globk box outer case assembly
3. Resistor
4. Under cover
5. Belt lock controller
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INSPECTION
RESISTOR CHECK
hl55JCADUsing a circuit tester, measure the resistance between the
terminals indicated below.
The condition can be considered satisfactory if the value
measured at this time is equivalent to the standard value.
Standard value
Terminals measuredStandard value fi
Between terminals a-- @Approx. 1.79 - 2.06
Between terminals
@ -@Approx. 1 .I 0 - 1.26
Between terminals @ - @Approx. 0.38 - 0.44vision

HEATERS AND MANUAL AIR CONDITIONER - Air Condikner Switch55-21
AIR CONDITIONER SWITCH
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REMOVAL AND INSTALLATIONRemoval steps
1. Center air outlet assembly
2. Air conditioner switch
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SERVICE POINTS OF REMOVALM55QBAH1. REMOVAL OF CENTER AIR OUTLET ASSEMBLY
Disengaging the clips (2 positions) of the center air outlet
assembly with a flat tip screwdriver, remove the center airoutlet assembly with the trim stick.
2. REMOVAL OF AIR CONDITIONER SWITCH
Remove the center air outlet assembly, and insert hand tothe back of the cluster panel assembly through the
produced opening. Push it toward you for removal.
INSPECTION
AIR CONDITIONER SWITCH CHECKM55QCAD
OFF.
0
light
If pressed 1 step (ECONOMY)
If pressed 2 steps(Air conditioner)
NOTE(1) The O-O symbol indicates continuity(2) *: 20A018ITSB Revision

55-22HEATERS AND MANUAL AIR CONDITIONER - Heater Unit
HEATER UNIT
REMOVAL AND INSTALLATION
M551A-
Pre-removal and Post-installation Operationl Draining and Supplying of the Coolant(Refer to GROUP 11 -Service AdjustmentProcedures.)l Removal and Installation of the Floor
Console and Instrument Panel
(Refer to GROUP
52A- Floor Console and
Instrument Panel.)Removal steps
-6 dx23. 2. 1.Connection Center Under cover reinforcement of water hoses
4. Distribution duct (foot)
5. Foot shower duct
6. Lap cooler duct
7. Evaporator
mounting bolt and nut -
8. Center duct
9. Heater unit
10. Plate11. Heater core
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Nith air
SERVICE POINT OF REMOVALM551BAS7. REMOVAL OF EVAPORATOR MOUNTING BOLT

NOTEIn order to prevent bolts from falling into the blower
assembly, set the inside/outside air-selection damper to theposition that permits outside air introduction.
INSPECTIONM55lCAJ
l Check the operation of dampers and link mechanism.
l Check the heater core for clogging and water leakage.
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