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.
6)
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.
Remed y
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
Re f r i g e r a t i n g
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 have found that the refrigerator
is gradually becoming not so cold and finally no refrigerating cab be achieved; ii) fast leakage
in that case, all the refrigerant will escape swiftly due to abrupt rupture of system tubing.
Symptoms of total leakage of refrigerant are mainly as follows: the compressor can be started
easily (if there is no damage to the compressor parts) and its operating current becomes low,
its gas suction pressure is high and discharge pressure is lower, the gas discharge tube feels
rather cold, no sound of gas eruption from the liquid in the evaporator can be heard, and no
will gush out of the process tube if you cut it open after shutdown.
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Summary of Contents for HB21FNN
Page 23: ...CIRCUIT DIAGRAM 1 Brief principle diagram 23 ...
Page 24: ...2 Connect diagram 24 CIRCUIT DIAGRAM ...
Page 40: ......
