A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to charge the refrigerant system with R-134a
refrigerant. Refer to the operating instructions sup-
plied by the equipment manufacturer for proper care
and use of this equipment.
REFRIGERANT CHARGE CAPACITY
The R-134a refrigerant system charge capacity for
this vehicle is 0.680 kilograms (1.50 pounds/24 ounc-
es).
PARTIAL CHARGE METHOD
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS GROUP BEFORE
CHARGING THE REFRIGERANT SYSTEM.
The partial charge method is used to add a partial
charge to a refrigerant system that is low on refrig-
erant. To perform this procedure the evaporator inlet
and outlet tube temperatures are measured. The
temperature difference is measured with a tempera-
ture meter with one or two clamp-on thermocouple
probes. The difference between the evaporator inlet
and outlet tube temperatures will determine the
amount of refrigerant needed.
Before adding a partial refrigerant charge, check
for refrigerant system leaks. See Refrigerant System
Leaks in this group for the procedures. If a leak is
found, make the necessary repairs before attempting
a full or partial refrigerant charge.
(1) Attach a manifold gauge set to the refrigerant
system service ports.
(2) Attach the two clamp-on thermocouple probes
to the inlet and outlet tubes of the evaporator coil.
a. If a single thermocouple probe is used, attach
the probe to the evaporator inlet tube just before the
collar of the refrigerant line connector fitting. The
probe must make contact with the bottom surface of
the evaporator inlet tube.
b. If dual thermocouple probes are used, attach
probe 1 to the evaporator inlet tube, and probe 2 to
the evaporator outlet tube. Attach both probes to the
evaporator tubes just before the collar of the refrig-
erant line connector fittings. The probes must make
contact with the bottom surfaces of the evaporator
inlet and outlet tubes.
(3) Open all of the windows or doors of the passen-
ger compartment.
(4) Set the A/C button on the heater-A/C controls
to the on position, the temperature control knob in
the full cool position, select the Recirculation Mode,
and place the blower motor switch in the highest
speed position.
(5) Start the engine and hold the engine idle speed
at 1,000 rpm. Allow the engine to warm up to normal
operating temperature.
(6) The compressor clutch may cycle, depending
upon ambient temperature, humidity, and the refrig-
erant system charge level. If the compressor clutch
cycles, unplug the wire harness connector from the
low pressure cycling clutch switch on the accumula-
tor. Install a jumper wire between the two cavities of
the switch wire harness connector.
(7) Hold the engine idle speed at 1,000 rpm.
(8) Allow three to five minutes for the refrigerant
system to stabilize, then record the temperatures of
the evaporator inlet and outlet tubes.
a. If a single probe is used, record the temperature
of the evaporator inlet tube. Then remove the probe
from the inlet tube and attach it to the evaporator
outlet tube just before the collar of the refrigerant
line connector fitting. The probe must make contact
with the bottom surface of the evaporator outlet tube.
Allow the thermocouple and meter time to stabilize,
then record the temperature of the evaporator outlet
tube. Subtract the inlet tube temperature reading
from the outlet tube temperature reading.
b. If dual probes are used, record the temperatures
of both the evaporator inlet and outlet tubes. Then
subtract the inlet tube temperature reading from the
outlet tube temperature reading.
(9) If the measured temperature differential is
higher than 22° C to 26° C (40° F to 47° F), add 0.4
kilograms (14 ounces) of refrigerant.
(10) Allow three to five minutes for the refrigerant
system to stabilize, then take a second set of thermo-
couple measurements. Record the temperature differ-
ence to determine if an additional charge is required.
(11) Record the compressor discharge pressure. If
the reading is higher than the pressure shown in the
Compressor Discharge Pressure chart (Fig. 1), the
system could be overcharged. If the reading is equal
to, or lower, than the pressure shown in the chart,
continue with this procedure.
(12)
EXAMPLE: The ambient temperature is 21°
C (70° F). The evaporator inlet tube temperature is
12° C (54° F) and the evaporator outlet tube temper-
ature is 10° C (50° F). Subtract the inlet tube tem-
perature from the outlet tube temperature. The
difference is -2° C (-4° F). With a -2° C (-4° F) tem-
perature differential at 21° C (70° F) ambient tem-
perature, the system is fully charged.
(13) Add enough refrigerant to bring the refriger-
ant system up to a full charge.
(14) Remove the jumper wire from the low pres-
sure cycling clutch switch wire harness connector
and plug the connector back into the switch.
24 - 2
HEATING AND AIR CONDITIONING
WJ
SERVICE PROCEDURES (Continued)
2000 JEEP GRAND CHEROKEE