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let the air come in ,or use a fan to speed up air flowing so as to shorten the time needed for
defrosting .Never strike the frost layer with any iron tools or wood stick in order to avoid
damage to the evaporator tubing .
6) Refrigerating oil left in evaporator tubing
Analysis of Trouble
During the process of refrigerating cycles ,a little refrigerating oil may remain in the
evaporator tubing ,and after a longer time of operation ,if there is considerable refrigerating
oil left in the evaporator ,the heat conduction effect will be severely affected ,thus causing a
poor refrigerating effect .
Remedy
It is quite difficult to determine whether this trouble is caused by the refrigerating oil left in
the evaporator tubing ,because this kind of phenomenon and other several trouble are
tends to be confused .Generally speaking ,you can make a judgment based on the frost
formed on the evaporator .If the frost does not cover the evaporator , and moreover ,it is
loosely formed ,you can make a judgment that the deterioration of refrigerating effect is
due to the accumulation of refrigerating oil left in the evaporator tubing in case no other
troubles have been found . To clear off refrigerating oil left in the evaporator ,dismantle the
evaporator ,purge it thoroughly and then dry it .In case it is difficult to dismantle it ,charge
refrigerant from the evaporator inlet to wash it several times ,then purge and dry it with
nitrogen .
7) Flowing obstructed in refrigerating system
Analysis of Trouble
Because the refrigerating system was originally not purged thoroughly ,some of the filter
screen meshes have been clogged by dirt accumulated in the filter after using it for a
certain time of period ,thus resulting in a decrease in flow rate ,and hence a poorer
refrigerating effect . The abnormal phenomena caused by this kind of slight clogging in the
system are as follows: the gas discharge pressure is lower ,the temperature of discharged
gas drops down ,the position clogged has a temperature lower than that in normal
conditions ,and for a severe clogging ,even dew condensation as frosting may appear .
Remedy
Purge the tubing ,and after replacing the dry filter with a new one or clearing it
thoroughly ,recharge the system with refrigerant and seal the charging port .
B. No Refrigerating
The phenomenon that the compressor runs normally ,but no frost (or only a little frost )
appears on the evaporator ,and the refrigerator temperature does not drop down is called
"no refrigerating". There are many causes for this trouble and it is relatively complicated ,
too . In servicing ,special attention to finding direct causes for this phenomenon .Three
main potential causes for this trouble are analyzed below :
1) All refrigerant in the system has leaked out
Analysis of Trouble
Leak points in the refrigerating system have not been found and repaired timely ,thus
resulting in the total escape of refrigerant .There are two kinds of leakage :
I)
slow leakage
for instance ,when we want to use a refrigerator that has been put out of
quite a long time ,we find the leakage of refrigerant ,or in the course of its operation ,we
