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6)
Refrigerating oil in evaporator tubing
Analysis of Problem
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 Problem
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 temperature of discharged gas, and, for
severe cases, condensation and frosting may appear.
Remedy
Purge the tubing. After replacing the dry filter or cleaning it thoroughly, refill the
system with refrigerant and seal the charging port.
•
No Refrigeration
“No refrigerating” refers to a situation where the compressor runs normally, but
the refrigerator’s temperature does not decrease. While servicing, careful
attention will be required to find and correct the cause. The most common causes
for this malfunction are analyzed below.
1) The Entire Refrigerant Has Leaked
Analysis of Problem
Leak points in the refrigerating system have not been found and repaired
timely, allowing refrigerant to leak completely. There are two kinds of leaks: slow
leaks
and fast leaks. Symptoms of total leakage of refrigerant are:
i. The compressor can be started easily (if there is no damage to the
compressor parts)
ii. The operating current becomes low
iii. The gas suction pressure increases
iv. The discharge pressure decreases
