Maintenance Service and Trouble Shooting
heard ,and no will gush out of the process tube if you cut it open after
shutdown .
Remedy
Check the whole machine , particularly those locations which are liable
to leak .After leak points have been found ,repair them or replace them with
new parts according to specific circumstances ,then evacuate the system
and finally charge refrigerant.
2) Refrigerating system has been clogged
a) Clogged with Ice
Analysis of Trouble
The dryness treatment for the major parts in the refrigerating system
has been performed improperly, the effect of air purging for the whole
system is not good ,or the water content in the refrigerant is out of
standard ,all these will cause the expansion valve to be clogged with
ice .The symptom for this trouble are as follows :the refrigerator sometimes
can refrigerate and sometimes cannot :the refrigerator compartment works
normally at the beginning ,but after working for a certain period of
time ,frosting begins at the clogged position ,evaporation temperature
reaches below 0
°
C , water will accumulate at the narrow part of the capillary
and clog it gradually ,then frost begins to melt at the evaporator ,no gas
flowing sound can be heard ,and the gas suction pressure assumes a state
of vacuum .Note that these phenomena will appear intermittently ;
sometimes ,the refrigerator works well ,and sometimes not well .In order to
determine whether it is clogged with ice ,heat the suspicious points with hot
water to make ice melt ,and after a while if a gas flowing sound resulting
from an abrupt gush is heard and the gas suction pressure rises as well ,it
can be confirmed that the trouble is caused by ice clogging .
Remedy
If there is too much moisture in the refrigerating system, it is advisable
to release the refrigerant, purge the tubing with nitrogen, and then charge
the system with the filtered refrigerant. However, the commonly adopted
method is to connect a filter with moisture absorbers (such as silica-gel,
anhydrous calcium chloride) to the refrigerating system so as to filter out
the moisture from the system, then replace the filter, evacuate it again and
finally charge the system with refrigerant.
b) Clogged with dirt in capillary
Analysis of Trouble
The capillary inlet is a place where coarse-grained dirt or refrigerant oil
in the system will tend to settle down and clog it. In case considerable dirt
accumulates there, the whole filter screen may be blocked totally, making
the refrigerant unable to go through. Clogging with dirt exhibits the same
symptoms as that with ice, namely, higher gas suction pressure, lower
temperature of discharged gas, and no gas flowing sound from the
evaporator. The difference between the both is as follows: if the clogging is
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