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a. Poor Refrigerating Effect
The “poor refrigerating effect “refers to when the refrigerator operates normally, but does
not cool to the temperature indicated by the thermostat. Possible causes are discussed and
analyzed below:
1) Refrigerant leaks
Analysis of Trouble
The refrigerant leaks will result in an insufficient refrigerating capacity. This will lead to
lower gas suction and exhaust pressure as well as hotter exhaust gas. The exhaust tube
will become extremely hot, and the sound of gas flowing from outlet of the capillary will
become louder than usual. After shut down, the balance pressure in the system is lower
than the saturation pressure corresponding to the same ambient temperature.
Remedy
Locate the refrigerant leak points immediately, and note welding points and parts where the
leaks occur. While troubleshooting, pay attention to those parts that are liable to leak,
check main connection points for oil seepage and tubing for cracks. After repairing the leak
points, refill the refrigerant. If you have problems detecting the leak points, charge the
system with nitrogen to help identify leaks. Drain the system of the nitrogen before refill with
refrigerant.
2) Too much refrigerant in the system
Analysis of Trouble
a) If amount of refrigerant in the system exceeds its nominal capacity, the excess
refrigerant will displace the evaporator. This will reduce the heat-dissipation area and
decrease the refrigerating efficiency. Malfunctions caused by excess refrigerant are: gas
suction and exhaust pressures increase, condenser becomes hotter, the electric current
of the compressor rises, frost forms on the evaporator and gas return tube, and the
refrigerator temperature drops slowly.
b) If excessive refrigerant has been charged, the liquid refrigerant that cannot evaporate in
the evaporator will return to the compressor. This will cause “liquid striking.” 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 cover the 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. After several
minutes, open the refrigerant charging tube and let the refrigerant escape from it, replace
the dry filter, refill the refrigerant after evacuating, and then seal the charging port.
3) There is air left in the refrigerating system