1991 MITSUBISHI 3000GT Service Manual

L
2OFOO85HEATERS AND MANUAL AIR CONDITIONER
- Trqubleshooting55-7
TROUBLESHOOTING HINTSInspection of Air Conditioner Control Unit
Disconnect the amplifier and inspect the connector on the wire
harness side as shown in the chart below.
Test Conditions:
(1) Ignition switch: ON
(2) Air conditioner switch: ON
(3) Temperature control lever: MAX. COOL
(4) Blower switch: HI
1 Terrrnal 1Signal
Conditions
8Auto compressor control unit groundAt all timesov
1Auto compressor control unit power
SUPPlY
When ignition switch is ON
Battery
voltage
6Air conditioner compressor relay
When all conditions for switch-ON of
Battery
the compressor are satisfiedvoltage
I ’I
Air conditioner switch: A/C
When air conditioner switch pressed inBattery
to second stepvoltage
Air conditioner switch: ECONO
When air conditioner switch pressed in
to first step
13Fin-therm0 sensor 0Ignition switch, blower switch and airApprox.
conditioner switch: ON2.5V/
LJ14Air-inlet sensor 0Ignition switch, blower switch and air
conditioner switch: ONApprox.IV
15Fin-therm0 sensor 0Ignition switch, blower switch and air
conditioner switch: ON
Ambient temperature: 4°C (39°F)
OV
18Air-inlet sensor 0Ignition switch, blower switch and air
conditioner switch: ON
Ambient temperature: 4°C (39°F)ov
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55-8HEATERS AND MANUAL AIR CONDITIONER - Troubleshooting
TROUBLESHOOTING QUICK-REFERENCE TABLE
Compressor doesn’t operate.
hen
no.
4
5
6
7
8
9
-
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L
switch terminals.
Sensor
”
1
InspectronCriteriapointIMethodProbable causeIRemedy
Abnormal
No sound is
notedFaulty magnetic clutchReplace magnetic clutch.
No continuity
Faulty blower switchReplace blower switch
No continuity
Faulty air conditioner
switchReplace air conditioner
switch.
No continuity
Faulty air magnetic clutch
relayReplace magnetic clutch
relay.
pa;?’ places where gas
II
Vo continuityFaulty dual-pressure switchReplace dual-pressure
\Jo continuityIFaulty thermostatswitch.Replace thermostat.
Outside range of3.9 to 4.1 kfiFaulty fin-therm0 sensorReplace fin-therm0 sensor
3utside range ofFaulty air inlet sensor1.9tol.l kQReplace air inlet sensor.
If no abnormality
is noted at each inspection point after inspection coducted in the sequence shown in this quick-reference table, it is suspected that
the compressor IS Inoperative because of faulty air conditioner control unit. Therefore, replace the air conditioner control unit.
d
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HEATERS AND MANUAL AIR CONDITIONER - safety Pre=utm55-9
SAFETY PRECAUTIONSR-12 refrigerant is a chlorofluoro-carbon
(CFC) that
can contribute to the depletion of the ozone layer in
the upper atmosphere.
Ozone filters out harmful radiation from the sun.
To assist in protecting the ozone layer, Mitsubishi
Motor Sales of America recommends that a R-12
refrigerant recycling device that meets SAE stan-
dard
J1991 be used.
Contact an automotive service equipment supplier
for refrigerant recycling equipment that is available
in your area.
The refrigerant used in all air conditioner is R-l 2. It is
transparent and colorless in both the liquid and
vapor state. Since it has a boiling point of
-29.8”C(-21.7”F), at atmospheric pressure, it will be a vapor
at all normal temperatures and pressures. The vapor
is heavier than air, non-flammable, and nonexplo-
sive. It is nonpoisonous except when it is in direct
contact with open flame. It is noncorrosive except
when combined with water. The following precau-
tions must be observed when handling R-12.
CautionWear safety goggles when servicing the refri-
geration system.R-12 evaporates so rapidly at normal atmospheric
pressures and temperatures that it tends to freeze
anything it contacts. For this reason, extreme care
must be taken to prevent any liquid refrigerant from
contacting the skin and especially the eyes. Always
wear safety goggles when servicing the refrigera-
tion part of the air conditioning system. Keep a
bottle of sterile mineral oil handy when working on
the refrigeration system. Should any liquid re-
frigerant get into the eyes, use a few drops of
mineral oil to wash them out. R-12 is rapidly
absorbed by the oil. Next splash the eyes with
plenty of cold water. Call your doctor immediately
even though irritation has ceased after treatment.
CautionDo not heat R-12 above 52°C
(125.6”F).
M55PAAFIn most instances, moderate heat is required to
bring the pressure of the refrigerant in its container
above the pressure of the system when charging or
adding refrigerant. A bucket or large pan of hot
water not over 52°C
(125.6”F) is all the heat required
for this purpose. Do not heat the refrigerant contain-
er with a blow torch or any other means that would
raise temperature and pressure above this tempera-
ture. Do not weld or steam clean on or near the
system components or refrigerant lines.
Caution
Keep R-12 containers upright when charging the
system.When metering R-12 into the refrigeration system,
keep the supply tank or cans in an upright position. If
the refrigerant container is on its side or upside
down, liquid refrigerant will enter the system and
damage the compressor.
CautionAlways work in a well-ventilated room.
Good ventilation is vital in the working area.
Although R-12 vapor is normally nonpoisonous,
contact with an open flame can cause the vapor to
become very poisonous. A poisonous gas is pro-
duced when using the flame-type leak detector.
Avoid inhaling the fumes from the leak detector.
CautionDo not allow liquid refrigerant to touch bright
metal.Refrigerant will tarnish bright metal and chrome
surfaces, and in combination with moisture can
severely corrode all metal surfaces.
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55-10 HEATERS AND MANUAL AIR CONDITIONER -Service Adjustment Procedures
OFF-----__-__1210235 2,1002,700
(30) (33)(299) (384)
Pressure Fil
2OPOOlL
SERVICE ADJUSTMENT PROCEDURES
M55FEAU
TEST PROCEDURESSIGHT GLASS REFRIGERANT LEVEL TEST
The sight glass is a refrigerant level indicator. To check the
refrigerant level, clean the sight glass and start the vehicle
engine. Push the air conditioner button to operate the com-
pressor, place the blower switch to high and move the
temperature control lever to MAX. COOL. After operating for a
few minutes in this manner, check the sight glass.
(I) If the sight glass is clear, the magnetic clutch is engaged,
the compressor discharge line is warm and the compressor
inlet line is cool; the system has a full charge.
(2) If the sight glass is clear, the magnetic clutch is engaged
and there is no significant temperature difference between
compressor inlet and discharge lines; the system has lost
some refrigerant.
(3) If the sight glass shows foam or bubbles, the system could
be low on charge. The system has to be charged with some
refrigerant.
MAGNETIC CLUTCH(1) Disconnect the wiring to the magnetic clutch.
(2) Connect battery (+) voltage directly to the wiring for the
magnetic clutch.
(3) If the magnetic clutch is normal, there will be a “click”. If
the pulley and armature do not make contact (“click”), there
is a malfunction.
v):
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RECEIVER DRIERTo Test the Receiver Drier
(1) Operate the unit and check the piping temperature by
touching the receiver drier outlet and inlet.
(2) If there is a difference in the temperatures, the receiver
drier is restricted.
Replace the receiver drier.
DUAL PRESSURE SWITCH (LOW PRESSURE SWITCH)
(I) Turn back the adaptor valve handle all the way and install it
to the low pressure side service valve.
(2) With the gauge manifold low pressure service valves
closed, connect the gauge manifold high pressure side
charging hose to the adaptor valve.
(3) Tighten the adaptor valve handle and open the service
valve.
(4) If there in continuity between the dual pressure switch
terminals when the low pressure side pressure is at the
level of dual pressure switch ON condition shown to the
left, the switch is functioning normally. If not, replace the
L/(switch.
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HEATERS AND MANUAL AIR CONDITIONER -Service Adjustment Procedures 55 1 1
lr In et sensor
2oFoo57
UC03xD:c.-;am$2lYXSC0x.x
xa0:: :,:::25 cc,ii 77h>Temperature20A043F
argqse
20M012FIN-THERM0 SENSOR AND AIR-INLET SENSOR
(1) Disconnect the sensor’s connector at the evaporator case,
and by using an ohmmeter, measure the resistance.
If the resistance is within
+I 0% of value of the characteris-
tic curve, the sensor is functioning normally.
(2) If the sensor is normal, there is a malfunction of the air
conditioner control unit, and it should be replaced.
COMPRESSOR DRIVE BELT ADJUSTMENTM55FJAGRefer to GROUP 11
- Engine Adjustment.
CHARGING PROCEDURESM55FTAB
INSTALLATION OF CHARGE EQUIPMENT
(I) Turn back the adaptor valve handle all the way and install
each adaptor valve to the high and low pressure service
valves.
(2) Tighten the adaptor valve handle and open the service
valves.
(3) Connect the charge valve to the T-joint:
(4) With the charge valve handle turned back all the way, install
the service can.
(5) Connect each charge equipment as illustrated.
NOTE
(4) Do not connect the high and low pressure sides
adversely. (Connect high pressure side to the con-
denser and low pressure side to the evaporator.)
(2) The indications
“DIS” and “SUC” on the compressor
indicate high and low pressure sides respectively.
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55-12 HEATERS AND MANUAL AIR CONDITIONER - Service Adjustment Procedures
CHARGING SYSTEMAdaDtor valve
Vacuum meter20MOli
l-TSB IHold this conditron
for 5 minutes.
Gas leak check
is evident
1
/ Refrigerant charge1The refrigerant system must have been evacuated using the
previous procedure before charging.
Charge using only R-12 refrigerant. R-12 is available in bulk
tanks or small cans. Follow the safety precautions for handling
R-12 as listed in this group.
CHARGING THE REFRIGERANTCHARGING WITH SMALL CANS
Wh,en using disposable cans of this type, follow carefully the
can manufacturers instructions.
(1) Start up the vacuum pump.
Caution1. Do not use the compressor for evacuation.
2. Do not operate the compressor in the vacuum
condition; damage may occur.
(2) Evacuate to a vacuum reading of 100
kPa (89.5 psi) or
higher (approx. IO minutes).
(3) Turn back the high pressure side adaptor valve all the way
and close the service valve.
(4) Stop the vacuum pump and allow to stand for 5 minutes.
(5) Check for leaks. (Good if the vacuum is held.)
(6) Tighten the charge valve handle to puncture the service
can.(7) Open the charge valve to charge the system with re-
frigerant.
(8) When the refrigerant is no longer drawn in, turn back the
low pressure side adaptor valve handle all the way and
close the service valve.
(9)
Chack for gas leaks using a leak detector.
vision
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HEATERS AND MANUAL AIR CONDITIONER - Service AdWment proceres 55-13. .
Charginglose
\Adaptor valve
Vacuum meter
T-joint
20M0121
(1O)Start the engine.(1l)Operate the air conditioner and set at the lowest tempera-
ture (MAX. COOL).
(12)Fix the engine speed at 1,500 rpm.
(13)Tighten the low pressure side adaptor valve and open the
service valve to charge specified amount of refrigerant.
Caution
If the service can is inverted, liquid refrigerant may bedrawn into the compressor damaging it by liquid
compression. Keep the service can upright to ensurethat refrigerant is charged in gas state.
(14)Upon completion of charging, turn back the low pressure
side adaptor valve handle all the way and close the service
valve.
CHARGING WITH REFRIGERANT RECOVERY AND RE-
CYCLING UNITWhen using refrigerant recovery and recycling unit, follow
carefully the instruction manual for the unit.
REMOVAL OF CHARGE EQUIPMENT(1) Close the charge
valve:(2) Remove the adaptor valve from each service valve.
(3) Remove the vacuum pump.
CautionDo not remove the service can, T-joints and adaptor
valves but keep them connected for next charge
operation.
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CautionRefrigerantR-l 2iAdaptorNever use the high pressure side as this may cause
/valve
refrigerant to flow back, using rupture of the servicecan.(7) Start the engine. Charge valvergmg hose
55-14 HEATERS AND MANUAL AIR CONDITIONER - Service Adjustment procedures
CORRECTING LOW REFRIGERANT LEVEL
(I) Install the charge valve to the service can with its handle
turned back all the way.
(2) Connect the charging hose to the charge valve.
(3) Connect the adaptor valve to the charging hose with itsL&lhandle turned back all the way.
(4) Tighten the charge valve handle to puncture the can.
(5) Operate the adaptor valve handle to bleed air.
(6) Install the adaptor valve to the low pressure side service
valve.
(8) Operate the air conditioner and set at the lowest tempera-
ture (MAX. COOL).
(9) Fix the engine speed at 1,500 rpm.
(10)Open the adaptor valve and charge refrigerant checking
level with the sight glass.
(1 l)Upon completion of charging, close the adaptor valve and
20M0128charge valve.
(12)Remove the adaptor valve from the service valve.
NOTEIf the service can is not emptied completely, keep the
charge valve and adaptor valve connected to the can for
next charging.
Adaptor
valve
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DISCHARGING SYSTEMUse the refrigerant recovery unit to discharge refrigerant gas
from the system.
NOTERefer to that Refrigerant Recovery and Recycling Unit Instruc-
tion Manual for operation of the unit.
REFILLING OF OIL IN THE AIR CONDITIONER SYSTEM
Too little oil will provide inadequate compressor lubrication and
cause a compressor failure. Too much oil will ,increase
discharge air temperature.
When a
FX-105VS compressor is installed at the factory, it
contains
160 cc (9.8 cu.in.) of refrigerant oil. While the air
conditioning system is in operation, the oil is carried through
the entire system by the refrigerant.
Some of this oil will be trapped and retained in various parts of
the system.
When the following system components are charged, it is
necessary to add oil to the system to replace the oil being
removed with the component.
Condenser: 8 cc
(5 cu.in.)Evaporator: 72 cc (4.4
cu.in.)Piping: 9.6 cc
(6 cu.in.)Receiver drier: 6.4 cc
(.4 cu.in.)
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