1991 MITSUBISHI ECLIPSE clutch

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)

24-18 HEATERS AND AIR CONDITIONING - Service Adjustment Procedures
(5) Screw a can of R-12 to the opened manifold valve. Be sure
gasket is in place and in good condition. Tighten refrigerantcan and manifold locking nut to insure a good seal. Do not
overtighten 8 to
11 Nm (6 to 8 ft.lbs.) is sufficient if gasket
is in good condition.
(6) Turn manifold valve (above the refrigerant can) completely
clockwise to puncture the can. This closes the valve and
seals the refrigerant in the can.
Caution
Never heat small cans of refrigerant over
40°C (104°F)as they may explode.
(7) Place the refrigerant in a large pan of water heated to 52°C
(104°F). Place pan of water containing the refrigerant can
on an accurate scale so the amount of refrigerant added
can be weighed. Open the refrigerant manifold valve.
(8) Purge all air from test hoses. Air in the system will be
trapped in the condenser causing abnormally high dis-
charge pressures and interfering with condensing of the
refrigerant.(9) Slightly loosen both test hoses at the gauge set manifold.
Tighten the hoses as soon as the air is purged.
(10)Slightly loosen charging hose connection at gauge set
manifold. This will purge air from the charging hose.
Tighten connection as soon as air is purged.
(I l)With vehicle windows open and hood up, operate engine at1,500 rpm and jump the low pressure switch terminals
located on the receiver drier so the clutch will remain
engaged.
(12)Place air conditioner control on air conditioner and place theblower switch on high.
(13)lf necessary, block the condenser to maintain a discharge
pressure of 1,422 to 1,520
kPa (206 to 220 psi). System
must be charged through the evaporator suction service
ports as follows:
(a) Slowly open the suction service gauge valve.
Meter flow of refrigerant by adjusting, the suciton
service gauge valve so that pressure registered at the
suction service gauge does not exceed 345 kPa (50 psi).Keep refrigerant container upright.
(b) Add refrigerant gas until there is no foam visible at the
sight glass.
Add an additional
170 g (6 oz.)
(c) Close the suction gauge valve.
CautionToo much refrigerant in the system can cause
abnormally high discharge pressures. Care must beused so that the exact recommended amount or
refrigerant is added after foam clears in the sight
glass.(d) Close dispensing manifold valve. Remove test hoses
and adapters from the service ports of compressor,
install protective caps at service ports and reconnect
wiring.(e) Check system performance.
(P.24- 16.)
e
. i”
A
i-4

24-24 HEATERS AND AIR CONDITIONING - Service Adjustment Procedures
COMPRESSOR NOISENUFIABWhen investigating an air conditioning related noise, you must
first know the conditions when the noise occurs. These
conditions are: weather, vehicle speed, in gear or neutral,
engine temperature or any other special conditions.
Noises that develop during air conditioning operation can oftenbe 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.
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 coilis tight (no rotation or wobble).
(3) Check refrigerant hoses for rubbing or interference that cancause unusual noises.
(4) Check refrigerant charge (See “Charging the 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.
Condenser fan motor relay,
Magnet clutch
relay, Blower
motor High
relayHeater relayML0312
16W908
POWER RELAY CHECKNUFNAE
NOTEFor information concerning the installation position of each
relay, refer to
P.24-8.CONDENSER FAN MOTOR RELAY, MAGNET CLUTCH
RELAY, BLOWER MOTOR HIGH RELAY, HEATER RELAY
Check for continuity between the terminals when- the battery
power-supply is applied to terminal (2). and terminal (4) is
grounded.
1 When current flows 1 Between terminals l-3 1 Continuity1
I
When no currentBetween terminals l-3 No continuity
flowsBetween terminals 2-4 Continuity
IKinks in the refrigerant tubing or sharp bends in the
Never attempt to rebend formed lines to fit. Use the
refrigerant hose lines will greatly reduce the
capac-correct line for the installation you are servicing.
ity of the entire system. High pressures are
pro-A good rule for the flexible hose lines is keep the
duced in the system when it is operating. Extreme
radius of all bends at least 10 times the diameter of
care must be exercised to make sure that all
the hose.
connections are pressure tight. Dirt and moisture
Sharper bends will reduce the flow of refrigerant.
can enter the system when it is opened for repair or
The flexible hose lines should be routed so that theyreplacement of lines or components. The following
are at least 80 mm (3 in.) from the exhaust manifold.precautions must be observed.
It is good practice to inspect all flexible hose lines atThe system must be completely discharged before
least once a year to make sure they are in good
opening any fitting of connection in the refrigeration
condition and properly routed.
Fsystem. Open fittings with caution even after the
Unified plumbing connections with O-rings. These
4’system has been discharged. If any pressure is
noticed as a fitting is loosened, allow trappedO-rings are not reusable.
pressure to bleed off very slowly.

HEATERS AND AIR CONDITIONING - ComDressor24-37
COMPRESSOR <7.8L Engine>
em REMOVAL AND INSTALLATION
F)
*Removal of the distributor CapPost-installation Operation
@Charging of Refrigerant
(Refer to P.24-21.)@Adjustment of Compressor DriveBelt (Refer to P.24-23.)*Checking for Gas Leakage(Refer to P.24-15.)*Performance Test(Refer to P.24-16.)Removal steps of compressor drive belt and
tension pulley
l *1, Compressor drive belt2. Tension pulley assembly installation bolt
3. Tension pulley assembly4. Bolt
5. Tension pulley6. Bolt
7. Adjustment plate
8. Tension pulley bracket2
13-15
ft.lbs.45-55 Nm
H 12 11
-10
2OAO456Removal steps of compressor
4*1. Compressor drive belt
9. Magnetic clutch harness connector
+e l * 10. Suction hose connection+e I)+ 11. Discharge hose connectionl a 12. O-rings
+* l + 13. Compressor14. Compressor bracket
NOTE(1) Reverse the removal procedures to reinstall.(2) l * : Refer to “Service Points of Removal”.
(3) W : Refer to “Service Points of Installation”.(4) m : Non-reusable parts.