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10
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
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.
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.
11
Maintenance Service and Trouble Shooting
6. Common Troubles in Refrigerators and Their Remedies
Causes for troubles occurring in refrigerators are closely related to the quality of components and
workmanship in assembling by manufacturers as whether refrigerators are properly used and
maintained .The parameters generally used to express the working conditions of a refrigerator
include the temperature inside the refrigerator ,operation rate ,electric power consumption ,noise
level ,and other functional indexes .If any one of these parameters is beyond its permissible
range ,this indicates that there is a fault or trouble in the refrigerator .
During the whole service life of a refrigerator ,the probability of troubles occurring within a union time
is called its failure rate .Making a comparison between the control circuit system of a refrigerator and
its refrigerating system ,we can find that the failure rate of the former is higher ,and that of the
thermostat is the highest . In troubleshooting ,the first thing you must do is to determine where the
trouble comes from --- the control system or the refrigerating system .There is general no trouble
indicating instrument mounted on the domestic refrigerator ,locations and natures of troubles should
be determined according to their respective features ,therefore ,experience in servicing is very
important to troubleshooting. Service technicians with rich experience can correctly locate them and
take reasonable remedy measures based on their comprehensive analysis of trouble characteristics
as well as operating conditions for various kinds of refrigerators.
Causes for troubles occurring in refrigerators are closely related to the quality of components and
workmanship in assembling by manufacturers as whether refrigerators are properly used and
maintained .The parameters generally used to express the working conditions of a refrigerator
include the temperature inside the refrigerator ,operation rate ,electric power consumption ,noise
level ,and other functional indexes .If any one of these parameters is beyond its permissible
range ,this indicates that there is a fault or trouble in the refrigerator .
During the whole service life of a refrigerator ,the probability of troubles occurring within a union time
is called its failure rate .Making a comparison between the control circuit system of a refrigerator and
its refrigerating system ,we can find that the failure rate of the former is higher ,and that of the
thermostat is the highest . In troubleshooting ,the first thing you must do is to determine where the
trouble comes from --- the control system or the refrigerating system .There is general no trouble
indicating instrument mounted on the domestic refrigerator ,locations and natures of troubles should
be determined according to their respective features ,therefore ,experience in servicing is very
important to troubleshooting. Service technicians with rich experience can correctly locate them and
take reasonable remedy measures based on their comprehensive analysis of trouble characteristics
as well as operating conditions for various kinds of refrigerators.
Three Essentials for Checkup
1) Look
a) Check the tubing of refrigerating system for cracks and various welding points for leaks; if leakage
occurs ,an oil stain can be seen definitely .
b) Check the suction and exhaust pressure values (high pressure and low pressure) of compressor
to see whether they are normal.
c) Check the conditions of frost attached to its evaporator and gas return tube .It is abnormal if frost
has formed on part of the evaporator or there is no frost attached to it.
d) Pay attention to the speed of temperature drop inside freezer compartment .It is abnormal if the
speed of temperature drop is obviously slower than the corresponding normal speed.
e) Check the environment to see if the whether is suitable for placing a refrigerator.
f) Check refrigerator door seal, case, table surface and heat insulation
g) Look at the main control board to ascertain if various indication states are normal.
a) Check the tubing of refrigerating system for cracks and various welding points for leaks; if leakage
occurs ,an oil stain can be seen definitely .
b) Check the suction and exhaust pressure values (high pressure and low pressure) of compressor
to see whether they are normal.
c) Check the conditions of frost attached to its evaporator and gas return tube .It is abnormal if frost
has formed on part of the evaporator or there is no frost attached to it.
d) Pay attention to the speed of temperature drop inside freezer compartment .It is abnormal if the
speed of temperature drop is obviously slower than the corresponding normal speed.
e) Check the environment to see if the whether is suitable for placing a refrigerator.
f) Check refrigerator door seal, case, table surface and heat insulation
g) Look at the main control board to ascertain if various indication states are normal.
12
2) Listen
a) Listen to the noises produced when the compressor is running hums from a fully enclosed
aggregate unit is the sound caused by overload indicating that the motor cannot be started normally,
meanwhile ,a clattering sound can be heard from inside the start relay ,which is produced because
the start contacts cannot be released normally .A whistling sound is caused by the high pressure
gas flowing out of the crack of the pressure tube inside the compressor ,and clucks are the sound of
striking after the suspended spring inside the compressor has broken .
During the normal operation of compressor ,a slight and uniform hum sound due to undulation of
electric current can be heard generally ,this is a normal phenomenon .However ,if it sounds like
"tong ,tong
a) Listen to the noises produced when the compressor is running hums from a fully enclosed
aggregate unit is the sound caused by overload indicating that the motor cannot be started normally,
meanwhile ,a clattering sound can be heard from inside the start relay ,which is produced because
the start contacts cannot be released normally .A whistling sound is caused by the high pressure
gas flowing out of the crack of the pressure tube inside the compressor ,and clucks are the sound of
striking after the suspended spring inside the compressor has broken .
During the normal operation of compressor ,a slight and uniform hum sound due to undulation of
electric current can be heard generally ,this is a normal phenomenon .However ,if it sounds like
"tong ,tong
",i.e., an impact sound inside the compressor ,this means that a large quantity of wet
vapour of refrigerant or refrigerating oil has come into the compressor cylinder ;if it sounds like
"dang ,dang
"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 .
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 .
13
3) Touch and Feel
a) Feel the compressor when running ,its temperature should be generally less than 90°C in the
normal state (it may exceed 90°C 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 .
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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