10
4) Low efficiency of compressor
Analysis of Trouble
Low efficiency of a refrigerating compressor refers to the actual reduction of gas discharge
capacity and the corresponding reduction of refrigerating capacity under the condition that
the refrigerant in the system is unchanged. This typically occurs when the compressor has
been in use for a long time.
Remedy
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. Inspect to see if there is
pressure at the discharge port with your finger. In a normal compressor, it is difficult to
block the discharge port with your finger.
5) Too thick frost layer formed on evaporator
Analysis of trouble
If a direct cooling refrigerator is to be used for a prolonged period, make sure that you
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 fall to the prescribed range.
Remedy
Turn the refrigerator off and prepare for defrosting. Open the refrigerator’s door to let air
inside or use a fan to speed up air moving into the refrigerator to quicken the defrosting
process. Never strike the frost layer with any iron tools or wooden stick in order not to
damage the evaporator tubing
.
6) Refrigerating oil in evaporator tubing
Analysis of Trouble
During the refrigerating cycles, small amounts of refrigerating oil may remain in the
evaporator tubing. However, if there is considerable refrigerating oil left in the evaporator
after an extended period of operation, the heat conduction effect will be severely affected.
The result is poor refrigerating effect.
Remedy
If there is no frost on the evaporator, then there is a high probability that the deterioration
of refrigerating effect is due to the accumulation of refrigerating oil in the evaporator tubing.
Remove accumulated refrigerating oil, dismantle the evaporator, purge it thoroughly, and
then dry it. If it is difficult to dismantle, fill the evaporator tubing with refrigerant from the
evaporator inlet several times to remove the refrigerating oil. Then, purge and dry it with
nitrogen.
7) Flow obstructed in refrigerating system
Analysis of Trouble
If the refrigerating system was not purged thoroughly, the filter screen meshes become
clogged by dirt. This results in a decrease in flow rate and a poor refrigerating effect. The
effects of clogged filters included: decrease of gas discharge pressure, the drop in the
