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) Refrigerating oil left in evaporator tubing  
Analysis of Trouble 
During the process of refrigerating cycles, a little refrigerating oil may remain in the 
evaporator tubing, and after a longer time of operation, if there is considerable refrigerating oil 
left in the evaporator, the heat conduction effect will be severely affected, thus causing a poor 
refrigerating effect. 
Remedy 
It is quite difficult to determine whether this trouble is caused by the refrigerating oil left in the 
evaporator tubing, because this kind of phenomenon and other several trouble are tends to be 
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