if it sounds like “tong, tong…”, i.e., an impact sound inside the compressor, this means that a 
large quantity of wet vapor of refrigerant or refrigerating oil has come into the compressor 
cylinder; if it sounds like “dang, dang…”, a striking sound of metal parts inside the 
compressor ,this means that some moving parts have loosened (note to differentiate this 
sound from those formed during starting or stopping the compressor).
b) Listen to the sound caused by the flowing of gas in the evaporator.
Open the refrigerator door while the compressor is in operation , incline your ear and listen 
attentively the gas flow sound inside the evaporator .If it sounds like gentle whistling
accompanied by a sound similar to water flowing ,this is the sound produced by the normal 
circulation of refrigerant within the evaporator .In case only the gas flowing sound can be 
heard and there is no water flowing sound ,this indicates that the refrigerant has already
percolated .If neither the flowing sound nor the gas sounds from the evaporator can be 
heard ,this means that the filter or capillary has been clogged . 
3) Touch and Feel 
a) Feel the compressor when running ,its temperature should be generally less than 90
 in case of running for a longer period of time ). 
b) After the compressor has operated normally for 5~10 minutes,  touch and feel the 
condenser, the temperature of its upper part should be higher than that of its lower part (or its
right part is hotter than its left part, depending on the type of condenser coil), this indicates 
that the refrigerant is circulating. If the condenser is not hot, this means the leakage of 
refrigerant, In case the condenser radiates heat for only several minutes and then cools down,
this means that the filter and capillary have been clogged. As for the forced air cooling 
condenser, hot air will be blown out of it; this means that the system is out of order. 
c) Feel the filter’s temperature. During the normal operation of refrigerating system, the 
temperature on the filter’s surface should be a little higher than the ambient temperature; if 
you touch it with your hand, you will have a sense of slight heat. In case dew condensation 
appears due to the fact that its temperature is obviously lower than the ambient temperature, 
this means that most meshes of its screen has been clogged, resulting in an obstructed 
flowing of refrigerant, thus causing a drop in temperature due to throttling. 
d)  Feel the temperature of exhaust gas from the refrigerating system .the exhaust gas should 
be very hot and this is the normal working state. For those refrigerator with enclosed type of 
compressor refrigerating system, no frost or dew drop will from on the gas suction tube, 
otherwise, there is something wrong in the system (Frosting and dew condensation may
appear for a very short time period when just starting the machine, this is a normal 
phenomenon).
Because a refrigerator is a combination of several components, they are related and have 
influence on each other .In case an abnormal phenomenon has been found through the above-
mentioned checkups, you need not to make a hasty conclusion based on only one abnormal 
phenomenon .It is advisable to find out two or more abnormal phenomenon, or conduct 
troubleshooting comprehensively with the aid of instruments or other ways, because several 
kinds of troubles may share a common abnormal phenomenon, and two or more abnormal
phenomena may occur simultaneously due to a certain trouble .With this method , you can 
reject some suspicious troubles and finally make a correct judgment . 
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