Table of Contents
Advertisement
VA
PLUMBING (Continued)
• 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.
• 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.
Ambient
16°C
Temperature
(60°F)
Compressor
1378 kPa
Discharge
(200 psi)
Pressure
(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.
SPECIFICATIONS
CHARGE CAPACITY
Always refer to the underhood HVAC Specification
Tag for the latest fill specification for the model being
serviced.
A/C COMPRESSOR
DESCRIPTION
The air conditioning system uses a Nippondenso
7SBU16C double-acting, variable swash plate-type
compressor on all models. This compressor has a
label identifying the use of R-134a refrigerant and
both the suction and discharge ports located on the
cylinder head.
Compressor Discharge Pressure Chart
21°C
27°C
(70°F)
(80°F)
1516 kPa
1723 kPa
(220 psi)
(250psi)
(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, the system
could be overcharged. If the reading is equal to, or
lower, than the pressure shown in the chart, continue
with this procedure.
32°C
(90°F)
1930 kPa
(280 psi)
OPERATION
The compressor is driven by the engine through an
electric clutch, drive pulley and belt arrangement.
The compressor is lubricated by refrigerant oil that is
circulated throughout the refrigerant system with the
refrigerant.
The compressor draws in low-pressure refrigerant
vapor from the evaporator through its suction port. It
then compresses the refrigerant into a high-pressure,
high-temperature refrigerant vapor, which is then
pumped to the condenser through the compressor dis-
charge port.
The compressor cannot be repaired. If faulty or
damaged, the entire compressor assembly must be
replaced. The compressor clutch, pulley, and coil, are
available for service.
DIAGNOSIS AND TESTING - COMPRESSOR
NOISE
When investigating an air conditioning related
noise, you must first know the conditions under
which the noise occurs. These conditions include:
weather, vehicle speed, transmission in gear or neu-
tral, engine speed, engine temperature, and any
other special conditions. Noises that develop during
air conditioning operation can often be 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 compressor clutch
assembly.
PLUMBING 24 - 49
38°C
43°C
(100°F)
(110°F)
2206 kPa
2413 kPa
(320 psi)
(350 psi)
Advertisement
Table of Contents
