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. 13), 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.
REFRIGERANT SYSTEM EVACUATE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE GENERAL INFORMATION SECTION
NEAR THE FRONT OF THIS GROUP BEFORE EVAC-
UATING THE SYSTEM.
If the refrigerant system has been open to the
atmosphere, it must be evacuated before the system
can be charged. If moisture and air enters the system
and becomes mixed with the refrigerant, the com-
pressor head pressure will rise above acceptable
operating levels. This will reduce the performance of
the air conditioner and damage the compressor.
Evacuating the refrigerant system will remove the
air and boil the moisture out of the system at near
room temperature. To evacuate the refrigerant sys-
tem, use the following procedure:
(1) Connect a R-134a refrigerant recovery/recy-
cling/charging station that meets SAE Standard
J2210 and a manifold gauge set to the refrigerant
system of the vehicle.
(2) Open the low and high side valves and start
the charging station vacuum pump. When the suc-
tion gauge reads 88 kPa (26 in. Hg.) vacuum or
greater, close all of the valves and turn off the vac-
uum pump.
(a) If the refrigerant system fails to reach the
specified vacuum, the system has a leak that must
be corrected. See Refrigerant System Leaks in the
Diagnosis and Testing section of this group for the
procedures.
(b) If the refrigerant system maintains the spec-
ified vacuum for five minutes, restart the vacuum
pump, open the suction and discharge valves and
evacuate the system for an additional ten minutes.
(3) Close all of the valves, and turn off the charg-
ing station vacuum pump.
(4) The refrigerant system is now ready to be
charged with R-134a refrigerant. See Refrigerant
System Charge in the Service Procedures section of
this group.
REFRIGERANT SYSTEM SERVICE EQUIPMENT
WARNING: EYE PROTECTION MUST BE WORN
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED
BEFORE CONNECTING TO, OR DISCONNECTING
FROM THE REFRIGERANT SYSTEM. FAILURE TO
OBSERVE THESE WARNINGS MAY RESULT IN PER-
SONAL INJURY.
When servicing the air conditioning system, a
R-134a refrigerant recovery/recycling/charging sta-
tion that meets SAE Standard J2210 must be used.
Contact an automotive service equipment supplier for
refrigerant
recovery/recycling/charging
equipment.
Refer to the operating instructions supplied by the
equipment manufacturer for proper care and use of
this equipment.
A manifold gauge set may be needed with some
recovery/recycling/charging equipment (Fig. 14). The
service hoses on the gauge set being used should
have manual (turn wheel), or automatic back-flow
valves at the service port connector ends. This will
prevent refrigerant from being released into the
atmosphere.
Ambient
16°C
21°C
27°C
32°C
38°C
43°C
Temperature
(60°F)
(70°F)
(80°F)
(90°F)
(100°F)
(110°F)
Compressor
1515 kPa
1655 kPa
1790 kPa
2070 kPa
2345 kPa
2690 kPa
Discharge
Pressure
(220 psi)
(240 psi)
(260 psi)
(300 psi)
(340 psi)
(390 psi)
Fig. 13 Compressor Discharge Pressure
24 - 30
HEATING AND AIR CONDITIONING
WJ
SERVICE PROCEDURES (Continued)