GE TBG440ANDR, Technician Service Manual

Page: 33 / 141

Page 33
VIII. MAINTENANCE OF ENVIRONMENTAL PROTECTION REFRIGERATOR
8.2.3 Nitrogen being used in tube welding
During the welding of tubes, the
oxidized dirt in the tubes will cause the
clogging of capillary tube. So nitrogen
must be used to blow (nitrogen welding)
the tubes during the welding.
8.2.4 Vacuum degree (enhance the
accuracy of vacuum degree)
i. Operational sequency of below
should be based for the vacuum
extraction and freon-filling.
The air in the freezing system
expecially in the case of oxygen, will
make ester become an oil-base
substance. Chemical reaction will be
developed by the oxidized oil and
metal in producing fluoride metal
which is one of the reasons of
capillary tube clogging. For this
reason, higher degree of vacuum is
required.
8.3 MAINTENANCE SEQUENCY FOR HFC-
134A FREEZING SYSTEM
8.3.1 Reactions for CRC-12
Upon repairing the freezing system,
connect the compound pressure gauge,
vacuum pump and filling tank as
indicated in the following figure. When
the repairs of HFC-134a system is
required, it is necessary to enhance the
vacuum degree and so, different the
connections will be applied (as per
figure of below).