1991 MITSUBISHI ECLIPSE engine

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 ---

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.

24-16 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

i
HEATERS AND AIR CONDITIONING - Service Adjustment Procedures 24-21Hot water40°C (104°F)
1467CHARGING SYSTEM
The refrigerant system must have been evacuated using the
previous procedure before charging.
Charge using only R-l 2 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 with Small Cans
When using disposable cans of this type, follow carefully the
can manufacturers instructions.
Caution
Never use these cans to charge into the high pressure side
of the system (compressor discharge port) or into a systemthat is at high temperature, because the high system
pressures could be transferred into the charging can
causing it to explode.
Keep the refrigerant manifold valves capped when not in use.
Keep a supply of extra refrigerant-can-to-refrigerant-manifold
gaskets on hand so that gaskets can be replaced periodically.
This will insure a good seal without excessive tightening of thecan or the manifold nuts.
(1) Attach center hose from manifold gauge set to refrigerant
dispensing manifold. Turn refrigerant manifold valves com-pletely anticlockwise so they are fully open.
Remove protective caps from refrigerant manifold.
(2) Screw refrigerant cans into manifold. Be sure
manifold-to-can gasket is in place and in good condition. Tighten can
and manifold nuts to 8 to 11 Nm (6 to 8
ft.lbs.).(3) Turn refrigerant manifold valves completely clockwise to
puncture the cans and close the manifold valves.
(4) Purge the air from the charging line by loosening the
charging hose at the gauge set manifold and turning one ofthe refrigerant valves anticlockwise to release refrigerant.
When the refrigerant gas starts escaping from the loose
connection, re-tighten the hose.
Caution
Never heat small refrigerant cans over
40°C (104°F) as
they may explode.
(5) Fully open all refrigerant manifold valves being used and
place the cans of refrigerant into a pan containing
40°C
(104°F) water. The water will warm the charging can and
aid in the transfer to the charge into the system. Place the
water pan and refrigerant cans on a scale and note the
weight.
(6)Place air conditioner control on air conditioner and place theblower switch on high.
(7) Open the discharge and suction gauge valves of the gaugemanifold, and charge gas from the both.
Keep refrigerant container upright.
(8) When suction of refrigerant is saturated, close the dis-
charge and suction gauge valves once, and start the
engine. Fix the engine revolution speed at approx. 1,500
rpm.

HEATERS AND AIR CONDITIONING - Service Adiustment Procedures 24-23
<
we2ouo2er
< 1.8L Engine>Tension/ wllevO-RING INSTALLATION
(1) Clean sealing surface.
(2) Make sure O-ring does not have any scratches.
(3) Connect fitting, install fastener, and torque to amount
shown in the illustration.
The internal parts of the refrigeration system will remain in
a state of chemical stability as long as pure-moisture-free
R-12 and refrigerant oil is used. Abnormal amounts of dirt,
moisture of air can upset the chemical stability and cause
operational troubles or even serious damage if present in
more than minute quantities.
When it is necessary to open the refrigeration system, have
everything you will need to service the system ready so the
system will not be left open any longer than necessary. Capor plug all lines and fittings as soon as they are opened to
prevent the entrance of dirt and moisture. All lines and
components in parts stock should be capped or sealed until
they are ready to be used. All tools, including the refrigerant
dispensing manifold, the gauge set manifold and test hosesshould be kept clean and dry.
COMPRESSOR DRIVE BELT ADJUSTMENT N24FJAESatisfactory performance of the air conditioning system is
dependent upon drive belt condition and tension. If the proper
tensions are not maintained, belt slippage will greatly reduce airconditioning performance and drive belt life. To avoid such
adverse effects, the following service procedure should be
followed:
(1) Measure the deflection with a force of
IOON (22 Ibs.)applied to belt mid-point between tension pulley and
compressor pulley.
(2) Any belt that has operated for a minimum of one half-hour
is considered to be a “used” belt. Adjust air conditioning
drive belt at the time of new-car preparation.
(3) Check drive belt tension at regular service intervals and
adjust as needed.
Standard value:
When a new belt is installed<1.8L Engine>4-5 mm
(.16-.2 in.)
<2.0L DOHC Engine> 4.5-5 mm (.18-.2 in.)
When the used belt’s tension is adjusted
5.5-6 mm
(.22-.24 in.)