Maintenance Service and Trouble Shooting
b) In case excessive refrigerant has been charged the liquid refrigerant that cannot
evaporates in the evaporator will return to the compressor, and thus a phenomenon of
"liquid striking" will occur The liquid refrigerant evaporates and effervesces as soon as
it flows into the refrigerating oil at the bottom of compressor. If the condition is severe,
foams will fill all over inside the compressor housing and be sucked by the piston.
causing damage to the components of compressor.
Remedy
According to the operating procedures ,it is mandatory to turn the machine off ,and
several minutes later ,open the refrigerant charging tube and let the refrigerant escape
from it .replace the dry filter ,recharge refrigerant after evacuating ,and then seal the
charging port.
3) There is air left in the refrigerating system
Analysis of Trouble
Residual air in the refrigerating system will reduce its refrigerating efficiency .The
prominent phenomena are the increase in its gas suction and exhaust pressures
(however, the gas exhaust pressure will not exceed its rated value ),obvious increase
in temperature in the segment from the compressor outlet to the condenser
inlet .Because there is air in the system ,both the gas exhaust pressure and
temperature will rise ,and moreover ,the gas flowing sound is intermittent and obviously
louder.
Remedy
After shut down for several minutes, open the tubing .evacuate it and then recharge the
system with refrigerant.
4) Low efficiency of compressor
Analysis of Trouble
Low efficiency of a refrigerating compressor refers to the actual reduction of gas
discharge capacity, and hence the corresponding reduction of refrigerating capacity,
under the condition that the refrigerant in the system is unchanged .This phenomenon
occurs mostly when the compressor has been used for quite a long time ,its moving
parts have worn to a considerable degree ,fit clearance between various parts have
increased and sealing property of its gas valve has deteriorated .resulting in an
decrease in its actual gas discharge capacity .
Methods of Judgment
Measure the high and low pressures with pressure gauges to see whether they are
normal. If an abnormal sound comes from the compressor or the temperature of its
causing is too high ,Cut the discharge port open and operate the compressor ,feel it if
there is pressure at the discharge port with your finger (For a normal compressor ,its
discharge port is difficult to be blocked with your finger if you just apply a little effort).
5)Too thick frost layer formed on evaporator
Analysis of Trouble
If a direct cooling refrigerator is to be used for a prolonged period of time, be sure to
defrost its evaporator regularly ;if you fail to do so ,the frost layer on the evaporator
tubing will become thicker and thicker .Heat conduction will be severely affected when
the whole tubing is wrapped with a transparent ice layer ,and finally the temperature in
the refrigerator cannot drop down to the prescribed range .
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