NR-BN30PGW, NR-BN30PGB, NR-BN30PS1, NR-BN30QGW, NR-BN30QGB, NR-BN30QW1, NR-BN30QS1 - Panasonic Other Service Manuals Service Manual (repair manual). Page 10

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Maintenance Service and Trouble Shooting 
5. Normal Phenomena
—Not Troubles for Refrigerators 
In a domestic refrigerator, there is not only a complicated electric control system, but also a 
refrigerating system that is difficult to discern whether it is in a good working condition. Both the 
systems are related and affect each other. If a certain part of a refrigerator works abnormally .Its 
refrigerating efficiency will decrease, operation properties will become unstable ,or even it cannot be 
used normally for those serious cases. 
Refrigerators are generally of larger volume, once troubles appear ,to send them to a service 
department is really a tough thing ,if such is the case ,the user will always be in 
suspense ,sometimes ,normal phenomena will be erroneously regarded as 
troubles .Therefore ,before we deal with the topics of frequently occurring troubles of refrigerators 
and their remedies ,we should firstly give a brief account of some normal 
phenomena which are not troubles .In case any one of such phenomena occurs ,there is no need to 
worry about it ,and the user can use it at total ease . 
1). When the compressor of a refrigerator has just stopped running, a rumbling sound can be heard 
from inside its evaporator .This is a sound caused by the flowing of refrigerant in the evaporator 
tubing .Because the pressure difference is still greater after the compressor has just stopped 
running ,the refrigerant will flow for a certain time , therefore ,this sound is a normal phenomenon. 
2). A click sound can often be heard from the refrigerator. This is a normal sound produced by the 
pull-in or release of the armature of a current deadweight start relay when starting the 
compressor .The compressor motor will produce a slight and uniform sound while it is running. This 
sound is not easy to be heard in the daytime, but of course it can be heard distinctly at night. 
3). The compressor consists of an electric motor and a compressing apparatus .During its normal 
operation ,the motor's stator core and windings will rise to a temperature in the range of 100°
C~110°C ,and the temperature of the piston and cylinder of the compressing mechanism can also 
reach as above 100°C due to the heat produced when compressing refrigerant .Most of the heat 
radiates to the air through the compressor casing ,therefore ,its casing is generally at a temperature 
between 85°C ~90°C ,it is very hot ,particularly in summer when the ambient temperature is 
higher .All these are normal phenomena . 
4). For the direct cooling refrigerator, a kind of irregular crack sound can be often heard when the 
compressor is running for a certain period of time or has just stopped its running. This sound is 
caused by the stress relief due to expansion and contraction when temperature changes, and will 
not affect the normal application of refrigerator.
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