Container Refrigeration Operation & Service

6-4T-309
a. Remove all refrigerant using a refrigerant recovery
system.
b. Therecommendedmethodtoevacuateanddehydrate
thesystemis to connect evacuation hosesatthecom-
pressor suction, compressor economizer and liquid
line service valve (see Figure 6-5). Be sure the ser-
vice hoses are suited for evacuation purposes.
c. The area between the suction modulating valve and
evaporator expansion valve may not be open to the
access valves. To ensure evacuation of this area,
check that the suction modulating valveis morethan
10% open at controller function code Cd01. If re-
quired, the suction modulating valve may be opened
by use of the controller function code Cd41 valve
overridecontrol.Ifpowerisnotavailabletoopenthe
valve, the area may be evacuated by connecting an
additional hose at the lowside access valve (item11,
Figure 2-2).
d. Testtheevacuationsetupforleaksbybackseatingthe
unit service valves and drawing a deep vacuum with
thevacuumpumpandgaugevalvesopen.Shutoffthe
pump and check to see if the vacuum holds. Repair
leaks if necessary.
e. Midseat the refrigerant system service valves.
f. Openthevacuumpumpandelectronicvacuumgauge
valves,iftheyarenotalreadyopen.St art thevacuum
pump. Evacuate unit until the electronic vacuum
gauge indicates 2000 microns. Close the electronic
vacuumgaugeandvacuumpumpvalves.Shutoffthe
vacuumpump.Waitafewminutestobesurethevac-
uum holds.
g. Break the vacuum with clean dry refrigerant 134a
gas. Raise system pressure to approximately 0.2 kg/
cm@ (2 psig), monitoring it with the compound
gauge.
h. Remove refrigerant using a refrigerant recoverysys-
tem.
i. Repeat steps f.and g. one time.
j. Removethecoppertubingandchangethefilter-drier.
Evacuate unit t o 500 microns. Close the electronic
vacuumgaugeandvacuumpumpvalves.Shutoffthe
vacuum pump. Wait five minutes to see if vacuum
holds. This procedure checks for residual moisture
and/or leaks.
k. With a vacuumstill in the unit, the refrigerantcharge
may bedrawn into thesystemfrom arefrigerantcon-
tainer on weight scales. Continue to paragraph 6.7
6
4
5
7
DS
10
1
2
3
8
9
1. Receiver or Water
Cooled Condenser
2. Compressor
3. Discharge Service
Valve
4. Economizer Service
Valve
5. Suction Service Valve
6. Vacuum Pump
7. Electronic Vacuum
Gauge
8. Manifold Gauge Set
9. Refrigerant Cylinder
10. Reclaimer
Figure 6-6. Compressor Service Connections
6.6.4 Procedure - Partial System
a. If the refrigerant charge has been removed from the
compressorforservice,evacuateonlythecompressor
by connecting the evacuation set--up at the compres-
sor service valves. (See Figure 6-6.) Follow evacua-
tion procedures of the preceding paragraph except
leave compressor service valves frontseated until
evacuation is completed.
b. If refrigerant charge has been removed from t he low
side only, evacuate the low side by connecting the
evacuation set--up at the compressor suction and
economizer service valves and the liquid service
valveexceptleavetheservicevalvesfrontseateduntil
evacuation is completed.
c. Once evacuation has been completed and the pump
has been isolated, fullybackseat theservicevalvesto
isolate the service connections and t hen continue
with checking and, if required, adding refrigerant in
accordance with normal procedures