been fou nd ,repair them or repl ace them with new parts according to spec ific 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 p arts in the refrigerating system has been performe d 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 som etimes can refrigerate and sometimes cannot :the refriger ator
compartment works normally at the beginning ,but af ter working for a certain period of time ,frosting
begins at the clogged position ,evaporation temperature reaches below 0
℃
, 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 w ith
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 ga s 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 nitroge n, and then charge the system with the f
iltered refrigera nt. Howeve r, the
commonly adopted method is to connect a filter with moisture absorbers (such as silica-gel, anhydrous
calcium chloride) to the refrigerating system so a s 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 blocke d
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 g as, and no gas
flowing sound from the evapo rator. The dif ference between the both is as fo llows: if the clogging is
caused by dirt , tapping the suspicious clogged point (generally in the capillary or the connection joint
of the filter) may cause the refrigerant to flow through partially, resulting in some corresponding change,
whereas in that case if you heat it with a hot towel, no reaction will happen, no flowing s ound can be
heard, moreover, there i s no periodi c change. After rejecting t he possibility of ice clogging, it can be
generally considered as the clogging due to dirt .
REMEDY
Dismantle the system, remove the d ry filter from i t, purge the t ubing with nitrogen, install a new filter,
then evacuate it and finally charge it with refrigerant.
C) Clogging in filter
ANALYSIS OF TROUBLE
Total clogging of a filter is rarely to occur. This trouble is mostly caused by the paste-like matter formed
from the subst ances filled into the system or other dust af ter t he refriger ator has be en used for a