air conditioner MITSUBISHI ECLIPSE 1991 Workshop Manual

HEATERS AND AIR CONDITIONING - Troubleshooting24-5
From previoys page.
When the resistance of the air-
therm0 sensor is measured[with the air conditioner switch
OFF and when the ambient
temperature of the
air-therm0sensor is
25°C (77“F)], is the
measured resistance approx.
1.5f0.15 kP?
INoMalfunction of tha air-therm0Refer to P.24-6.-sensor.
Refer to P.24-6.
1Yes
When the resistance of the air-
inlet sensor is measured [with the
air conditioner switch OFF andwhen the ambient temperature of
the air-inlet sensor is 25°C (77”F)l
is the measured resistanceapprox.
1.5f0.15 k&2?I
1 Yes
Does idle-up occur immediatelyNo Malfunction of the DC motor
after the air conditioner switch is
cl800 Engine>
switched ON?Malfunction of the stepper motor
Yes~2000 DOHC Engine>
Malfunction of the MPI control unit
* Malfunction of the air conditioner
control unit.Refer to P.24-6.

24-6HEATERS AND AIR CONDITIONING - TroubleshootingAIR CONDITIONER CONTROL
UNIT CIRCUIT
1 Battery IBlower switch
litalAir conditioner
IAir inlet Air outlet1-isensorsensor
temperature
Corn- L Tpressor
relayI IMagnetic
AclutchMPI control*Wire harness sideDescription of Operation
(1) A negative-characteristic thermistor is employed
for the air-therm0 sensor and the air-inlet sensorin order to convert the ambient temperature at
the sensor part to resistance.
The sensor power-supply voltage
(5V) of the air
conditioner control unit is applied to each sen-
sor.
(2) The compressor operation mode changes (fromOFF to ECONO to A/C...) each time the air
conditioner switch is pressed. When the air
conditioner switch is pressed in to the first step,the mode is changed to the ECONO mode (the
indicator illuminates in orange, and the voltage
at terminal 4 of the air conditioner switch
becomes Bv.
When pressed in to the second step, the mode
is changed to the air conditioner mode (the
indicator illuminates in green), and the voltage at
terminal 2 of the air conditioner switch becomes
Bv.Bv: Battery voltage
(3) The output (terminal 4) of the air conditioner
control unit is output when all of the following
conditions are satisfied.
@ The air conditioner switch is ON (ECONO or
A/C mode).
@ The air-therm0 sensor ambient temperature
(evaporator outlet air temperature) is
4°C
(39°F) or higher.
@ The air-inlet sensor ambient temperature
(evaporator intake air temperature) is
4°C
(39°F) or higher.

HEATERS AND AIR CONDITIONING - Troubleshootinq
-.
’ Wire harness sideTROUBLESHOOTING HINTS
Inspection of Air Conditioner Control Unit
Disconnect the amplifier and inspect the connector on the wireharness side as shown in the chart below.
Test Conditions:
(1) Ignition switch: ON
(2) Air conditioner switch: ON
(3) Temoerature control lever: MAX COOL2OAO405
(4j Bloier switch: HI
TerminalMeasurement item
Tester connectionConditions
Specified value
1Resistancel-6-1,500f150 sz ’at 25°C (77°F)
2
10
Voltage2-3
2-8Airtcchonditioner
ContinuityContinuity3-Ground
4-Ground
Resistance5-7
-ContinuityII
8-Ground-
Voltage9-3
9-8Therm0 sensor OFF78°C (172°F)
:5k (185°F)
Voltage10-3ECONO switch
10-8
System voltageov
Continuity
Continuity1,500+
150 s-2at 25°C (77’F)
Continuity
System voltageov
System? voltageov
If the connector on the wire harness side is correct, replace the air conditioner control unit.

24-8HEATERS AND AIR CONDITIONING - Troubleshooting
IARNESSES AND COMPONENTS LAYOUT DIAGRAM
1. Air conditioner switch
2. Air conditioner control unit
3. Air-inlet sensor
4.
Air-therm0 sensor
36AOO51
NameSymbolAir conditioner control unit
DAir conditioner switch
GAir inlet sensor
FAir
therm0 sensorFBlower motor High relay
E
IrrIor:enser fan motor High-Low selecting
C
NameCondenser fan motor relay
Dual pressure switch
Engine coolant temperature switch
<2.0L DOHC Engine>
Heater relay
Magnetic clutch relay
Symbol
C
BA
H
C
NOTEThe “Name” column is arranged in alphabetical order.
q \
q ---

24-10HEATERS AND AIR CONDITIONING - Safety Precautions
SAFETY PRECAUTIONSN24PAAD
The refrigerant used in all air conditioner is R-l 2. It istransparent and colorless in both the liquid and
vapor state. Since it has a boiling point of
-29.8”C(-85.6”F).
at atmospheric pressure, it will be a vapor
at all normal temperatures and pressures. The vaporis heavier than air, non-flammable, and nonexplo-
sive. It is nonpoisonous except when it is in direct
contact with open flame. It
ia noncorrosive except
when combined with water. The following precau-
tions must be observed when handling
R-12.Caution
Wear safety goggles when servicing the refriger-ation 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.
Caution
Do not heat
R-12 above 40°C (104°F).In 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
40°C (104°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. Ifthe refrigerant container is on its side or upside
down, liquid refrigerant will enter the system and
damage the compressor.Caution
Always work in a well-ventilated room.
‘irrGood ventilation is vital in the working area. Always
discharge the refrigerant into the service bay ex-
haust system or outside the building. Large quanti-
ties of refrigerant vapor in a small, poorly ventilated
room can displace the air and cause suffocation.
Although
R-12 vapor is normally nonpoisonous,
contact with an open flame can cause the vapor to
become very poisonous. Do not discharge large
quantities of refrigerant in an area having an open
flame. A poisonous gas is produced when using theflame-type leak detector. Avoid inhaling the fumes
from the leak detector.
Caution
Do 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.
R-12 Refrigerant Bundling
Refrigerant Recycling
R-12 refrigerant is a chloro-floro-carbon (CFC) that
can contribute to the depletion of the ozone layer in
the upper atmosphere.A
Ozone filters out harmful radiation from the sun.
- -/.To assist in protecting the ozone layer, Mitsubishi
Motors Corporation
recomends that a R-12 re-
frigerant recycling device that meets SAE standard
J1991 be used.
Contact an automotive service equipment supplier
for refrigerant recycling equipment that is available
in your area.
Refer to the operating instructions provided with therecycling equipment for proper operation.

HEATERS AND AIR CONDITIONING - Service Adjustment Procedures 24-I 1
SERVICE ADJUSTMENT PROCEDURES
MANIFOLD GAUGE SET INSTALLATION
Suction
gauge
N24FDAF
Discharge
hose
7 Discharge
Port20A0460Manifold Gauge Valves-should be closed when connecting the manifold gauge set to the service port of
the compressor and the discharge hose. The suction gauge valve at the left is opened to provide a passage
between the suction gauge and the center manifold outlet. The discharge gauge valve at the right is openedto provide a passage between the discharge pressure gauge and the center manifold outlet.
Detailed instructions for proper use of the gauge set manifold are contained in the text covering each test andservice operation employing these gauges.
Suction Gauge-the left side of the manifold set is calibrated to register 0 to
100 kPa (0 to 15 psi) and 0 to
1,000
kPa (0 to 145 psi). This gauge is connected to the suction port of the compressor.
Discharged Gauge-the right of the manifold set is calibrated to register 0 to
2,100 kPa (0 to 305 psi). For all
tests this gauge is connected to the discharge port of the system.
Center Manifold Outlet-provides the necessary connection for a long service hose used when discharging
the system, using a vacuum pump to “pull a vacuum”before charging the system, and for connecting the
supply of refrigerant when charging the system.
TEST PROCEDURESN24FEAS
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.
SIGHT 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
compressor, place the blower switch to high and move the
temperature control lever to max cool. After operating for a fewminutes in this manner, check the sight glass.
(1) If the sight glass is clear, the magnetic clutch is engaged,
the compressor discharge line is warm and the compressorinlet 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.

24-12 HEATERS AND AIR CONDITIONING - Service Adjustment Procedures
------__--210 2352,100 Pressure
(30) (33)(299) 2&
kPa(psi)2OPOO14(3) If the sight glass is clear and the magnetic clutch is
disengaged; the clutch is faulty or, the system is out of
refrigerant. Perform low pressure switch test to determine
condition. Check low pressure switch, and clutch coil for
electrical continuity.
(4) If the sight glass shows foam or bubbles, the system could
be low on charge. Occasional foam or bubbles are normal
when the ambient temperature is above
43°C (110°F) or
below
21°C (70°F).Adjust the engine speed to 1,500 rpm. Block the air-flow
thru the condenser to increase the compressor discharge
pressure to 1,422 to 1,520
kPa (206 to 220 psi). If sight
glass still shows bubbles or foam, system charge level is
low.The refrigerant system will not be low on charge unless
there is a leak. Find and repair the leak. If the leak can be
repaired without discharging the system an oil level check
is not necessary. Use the procedure for correcting low
refrigerant level found in the Refrigerant System Service
Procedure Section.DUAL PRESSURE SWITCH
The dual-pressure switch is a combination of the low-pressureswitch (for checking the quantity of refrigerant) and the,
high-pressure switch (for prevention of overheating); it is
installed on the tube, and, when the pressure becomes
approximately 210 kPa (30 psi) or lower, the compressor stops,thus preventing the compressor from being damaged by heat.
When the pressure reaches 2,700
kPa (384 psi) or higher, the
compressor stops, thus preventing overheating. There is
generally no necessity for inspection; if, however, an unusual
condition, such as non-operation of the compressor is encoun-tered, check by following the procedures below.
(1) Check for continuity of the dual-pressure switch.
NOTEIf the air temperature drops to
0°C (32°F) or lower during
cold weather, the air conditioner will not operate (no
continuity).(2) If there is an insufficient amount of refrigerant, check the
refrigerant amount by looking through the sight glass of thereceiver; supply refrigerant if necessary.
(Refer to P.24-21.)

HEATERS AND AIR CONDITIONING - Service Adjustment Procedures 249*I3
--Air-therm0
sensor
Air inlet
sensor
E>aporator(3)
Set the gauge manifold in place and check whether or not
the pressure at the high-pressure side has become the
dual-pressure switch activation pressure.
(4) Replace the switch if, under ordinary conditions, there is no
continuity.Caution
The condition can be considered to be satisfactory if
there is continuity.
Never increase the pressure in a deliberate attempt to
obtain an abnormally high temperature, because to do
so risks blowing the compressor relief valve.AIR-THERM0 SENSOR AND AIR-INLET SENSOR
If frost forms on the surfaces of the evaporator fins, the cause
might be a malfunction of
air-therm0 sensor.
The temperature of the air-flowing from the evaporator’s outlet
is sensed by the thermistor, and the signals conveying this dataare input to the air conditioner control unit, thus switching the
compressor’s clutch ON or OFF.
This functions when the evaporator’s air-flow is low, or the
evaporator’s fins are clogged by dust, etc., or when the amountof refrigerant is insufficient.
These sensors detect the temperature within the passenger
compartment and the temperature at the cooling unit inlet,
thus causing changes of the resistance value, and this data is
provided to the air conditioner control unit as input.
How to Test the Therm0 Sensor and Air-Inlet Sensor
(1) Disconnect the sensor’s connector at the evaporator case,
and by using an ohmmeter, measure the resistance. The
resistance is normal if it is within the range shown in the
figure at the left; if the resistance is not normal, replace.
(2) If the sensor is normal, there is a malfunction of the air
conditioner control unit, and it should be replaced.
Standard value:
Passenger compartment temperature sensor resist-
ance value:
0°C (32°F)4,852+243 (S-2)
15°C (59°F)2,341+234 (S-2)
25°C (77°F)1,500+150 (52)
ENGINE COOLANT TEMPERATURE SWITCH
<2.0L DOHC Engine>
The engine coolant temperature switch is connected in series
with the compressor magnetic clutch power relay.
It disengages the compressor when the temperature of
engine coolant rises above
115°C (239°F).This is designed to prevent engine overheating when cooling
air is not sufficient for the condenser and radiator. If the enginecoolant temperature switch operates to disengage the com-
pressor, check for the condenser and radiator surface condi-
tions, belt tension and engine coolant level and correct, if
necessary.

24-14 HEATERS AND AIR CONDITIONING - Service Adjustment Procedures
-Discharge
w-w
SuctiongaugeDischalgauge
2OUO306
SuctiongaugeDischargegauge
2OUO307--
MAGNETIC CLUTCH(I) 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.
Using an ohmmeter, measure the resistance of the clutch
coil between the clutch lead wire and ground.
Standard resistance: 3.4-3.8
Q at 20°C (88°F)If resistance is not as specified, replace the coil.
COMPRESSOR(1) Install the manifold gauge set, and run the air conditioner.
(2) If a pressure of approx. 490 kPa (71 psi) is indicated on the
suction gauge side and a pressure of approx. 883
kPa (128
psi) is indicated on the discharge gauge side, the compres-
,“ssor has abnormal compression.
-IReplace the compressor.
(3) If a pressure of 294 to 392 kPa (43 to 57 psi) is indicated on
the suction gauge side and a pressure of approx. 1,961
kPa(284 psi) is indicated on the discharge gauge side, it is
suspected that air is present in the air conditioning system.Discharge the system, evacuate and recharge with speci-
fied amount of refrigerant.
(4) During operation of the air conditioner, cold air may stop
flowing after the elapse of time and this state is maintainedbefore cold air flows out again. If cold air stops flowing out
with negative pressure indicated on the suction gauge sideand a pressure of 588 to 980
kPa (85 to 142 psi) indicated
on the discharge gauge side, it is suspected that water is
present in the air conditioning system.
L=I
Discharge the system. Replace receiver drier. Evacuate and-check for leaks, and recharge with specified amount of
refrigerant.

24-16 HEATERS AND AIR CONDITIONING - Service Adjustment Procedures
PERFORMANCE TESTN24FWAFa(1) Park the tested vehicle at the area which is not exposed to
the direct sunlight.
(2) Connect a tachometer and manifold gauge set.
(3) Set the controls of the air conditioner as follows:
Air conditioning switch: A/C-ON position
Mode selection lever: Face position
Temperature control lever: Max. cooling position
Air selection lever: Recirculation position
Blower switch: HI (Fast) position
(4) Start engine and adjust rpm to 1,000 with air conditioner
clutch engaged.
(5) Engine should be warmed up with doors, windows close
and hood open.
(6)Insert a thermometer, to a depth of 20-30 mm (8-I .2 in.),into the left center air conditioner outlet, and operate the
engine for
20 minutes.
(7) Note the discharge air temperature.
NOTEIf the clutch cycles, take the reading before the clutch
disengages.
PERFORMANCE TEMPERATURE CHART
Garage ambienttemperature “C (“F)21 (70)26.7 (80)32.2(90)37.8(100)43.3(110)
Discharge air2.0-8.02.0-8.02.0-8.04.0-11.06.0-14.0temperature
“C (“F)(35.6-46.4)(35.6-46.4)(35.6-46.4)(39.2-51.8)(42.8-57.2)
Compressordischarge pressure900-1.3001.000-1.400l,lOO-1,5001,300-1,7001,500-1,900
kPa (psi)(128-186)(142-199)(156-212)(186-242)(212-270)
’Compressor suction50-15080-180100-200130-230150-250
pressurekPa (psi)(7.1-21.3)(11.4-25.6)(14.2-28.4)(18.5-32.7)(21.3-35.6)