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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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7 Analysis of Troubles and Troubleshooting
A. Poor Refrigerating Effect.
The so-called "poor refrigerating effect " refers to the fact that the refrigerator can operate and
refrigerator normally ,but the temperature in the refrigerator cannot drop to the prescribed value
under the stipulated working conditions .In view of there are many causes for this phenomenon ,we
are going to discuss and analyze it in the following 7 aspects :
1) Leakage of refrigerant
Analysis of Trouble
The leakage of refrigerant in the system will result in an insufficient refrigerating capacity, the
A. Poor Refrigerating Effect.
The so-called "poor refrigerating effect " refers to the fact that the refrigerator can operate and
refrigerator normally ,but the temperature in the refrigerator cannot drop to the prescribed value
under the stipulated working conditions .In view of there are many causes for this phenomenon ,we
are going to discuss and analyze it in the following 7 aspects :
1) Leakage of refrigerant
Analysis of Trouble
The leakage of refrigerant in the system will result in an insufficient refrigerating capacity, the
resulting phenomena are its lower gas suction pressure and exhaust pressure as well as higher
exhaust gas temperature. The exhaust tube feels rather hot, and a continuous gas flowing sound
louder than usual can be heard at the outlet of the
exhaust gas temperature. The exhaust tube feels rather hot, and a continuous gas flowing sound
louder than usual can be heard at the outlet of the
capillary and no frost or a smaller quantity of loose frost appears on the evaporator .After shut
down ,the balance pressure in the system is usually lower than the saturation pressure
corresponding to the same ambient temperature .
Remedy
In case there is leakage of refrigerant from the system, do not hurry to recharge it with refrigerant,
manage to find out leak points immediately, and make a note of from where it leaks ---welding points
and parts .After having them repaired, recharge refrigerant .
There are so many joints and sealed There are so surfaces in a refrigerator ,accordingly ,quite a lot
potential leak points do exist in the system .In troubleshooting ,pay attention to those parts that are
liable to leak ,check main connection points for oil seepage and tubing for cracks .If there is no
severer leak point ,charge the system with nitrogen and detect leak points with the commonly
adopted method ,repair them ,evacuate ,charge the system with refrigerant, and then turn on the
refrigerator to make a test run .
2) Too much refrigerant charged into the system
Analysis of Trouble
a) In case the amount of refrigerant charged into the system exceeds its nominal capacity ,the
superfluous refrigerant will of course take some space of the evaporator ,thus reducing its
heat-dissipation area and hence the refrigerating efficiency of the system .The abnormal
phenomena caused by this reason are as follows :the gas suction and exhaust
pressures are generally higher than their respective normal values ,the temperature of its condenser
is higher and the electric current of the compressor rises ,loose frost forms on the evaporator ,the
refrigerator temperature drops slowly ,and frost appears on the gas return tube .
b) In case excessive refrigerant has been charged, the liquid refrigerant that cannot evaporates in
the evaporator will return to the compressor and thus a phenomenon of "liquid striking" will
occur .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 fill all over 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 ,and several minutes
down ,the balance pressure in the system is usually lower than the saturation pressure
corresponding to the same ambient temperature .
Remedy
In case there is leakage of refrigerant from the system, do not hurry to recharge it with refrigerant,
manage to find out leak points immediately, and make a note of from where it leaks ---welding points
and parts .After having them repaired, recharge refrigerant .
There are so many joints and sealed There are so surfaces in a refrigerator ,accordingly ,quite a lot
potential leak points do exist in the system .In troubleshooting ,pay attention to those parts that are
liable to leak ,check main connection points for oil seepage and tubing for cracks .If there is no
severer leak point ,charge the system with nitrogen and detect leak points with the commonly
adopted method ,repair them ,evacuate ,charge the system with refrigerant, and then turn on the
refrigerator to make a test run .
2) Too much refrigerant charged into the system
Analysis of Trouble
a) In case the amount of refrigerant charged into the system exceeds its nominal capacity ,the
superfluous refrigerant will of course take some space of the evaporator ,thus reducing its
heat-dissipation area and hence the refrigerating efficiency of the system .The abnormal
phenomena caused by this reason are as follows :the gas suction and exhaust
pressures are generally higher than their respective normal values ,the temperature of its condenser
is higher and the electric current of the compressor rises ,loose frost forms on the evaporator ,the
refrigerator temperature drops slowly ,and frost appears on the gas return tube .
b) In case excessive refrigerant has been charged, the liquid refrigerant that cannot evaporates in
the evaporator will return to the compressor and thus a phenomenon of "liquid striking" will
occur .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 fill all over 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 ,and several minutes
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later ,open the refrigerant charging tube and et 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) Too thick frost layer formed on evaporator
Analysis of Trouble
If a direct cooling refrigerator is to be used for a prolonged period of time ,be sure to defrost its
evaporator regularly ;if you fail to do so ,the frost layer on the evaporator tubing will become thicker
and thicker .Heat conduction will be severely affected when the whole tubing is wrapped with a
transparent ice layer ,and finally the temperature in the refrigerator cannot drop down to the
prescribed range .
Remedy Turn the refrigerator off, and make preparations for defrosting ,open the refrigerator door to
let the air come in ,or use a fan to speed up air flowing so as to shorten the time needed for
defrosting .Never strike the frost layer with any iron tools or wood stick in order to avoid damage to
the evaporator tubing .
6) 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
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) Too thick frost layer formed on evaporator
Analysis of Trouble
If a direct cooling refrigerator is to be used for a prolonged period of time ,be sure to defrost its
evaporator regularly ;if you fail to do so ,the frost layer on the evaporator tubing will become thicker
and thicker .Heat conduction will be severely affected when the whole tubing is wrapped with a
transparent ice layer ,and finally the temperature in the refrigerator cannot drop down to the
prescribed range .
Remedy Turn the refrigerator off, and make preparations for defrosting ,open the refrigerator door to
let the air come in ,or use a fan to speed up air flowing so as to shorten the time needed for
defrosting .Never strike the frost layer with any iron tools or wood stick in order to avoid damage to
the evaporator tubing .
6) 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
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the evaporator tubing ,because this kind of phenomenon and other several trouble are tends to be
confused .Generally speaking ,you can make a judgment based on the frost formed on the
evaporator .If the frost does not cover the evaporator , and moreover ,it is loosely formed ,you can
make a judgment that the deterioration of refrigerating effect is due to the accumulation of
refrigerating oil left in the evaporator tubing in case no other troubles have been found . To clear off
refrigerating oil left in the evaporator, dismantle the evaporator, purge it thoroughly and then dry it .In
case it is difficult to dismantle it, charge
refrigerant from the evaporator inlet to wash it several times ,then purge and dry it with nitrogen .
7) Flowing obstructed in refrigerating system
Analysis of Trouble
Because the refrigerating system was originally not purged thoroughly ,some of the filter screen
meshes have been clogged by dirt accumulated in the filter after using it for a certain time of
period ,thus resulting in a decrease in flow rate ,and hence a poorer refrigerating effect . The
abnormal phenomena caused by this kind of slight clogging in the system are as follows: the gas
discharge pressure is lower, the temperature of discharged gas drops down, the position clogged
has a temperature lower than that in normal conditions and for a severe clogging ,even dew
condensation as frosting may appear .
Remedy
Purge the tubing, and after replacing the dry filter with a new one or clearing it thoroughly, recharge
the system with refrigerant and seal the charging port .
B. No Refrigerating
The phenomenon that the compressor runs normally, but refrigerator temperature does not drop
down is called "no refrigerating". There are many causes for this trouble and it is relatively
complicated, too. In servicing, special attention to finding direct causes for this phenomenon .Three
main potential causes for this trouble are analyzed below:
1) All refrigerant in the system has leaked out
Analysis of Trouble
Leak points in the refrigerating system have not been found and repaired timely, thus resulting in the
total escape of refrigerant .There are two kinds of leakage:
I) slow leakage for instance, when we want to use a refrigerator that has been put out of quite a
long time, we find the leakage of refrigerant, or in the course of its operation, we have found that the
refrigerator is gradually becoming not so cold and finally no refrigerating cab be achieved ;
ii) fast leakage in that case, all the refrigerant will escape swiftly due to abrupt rupture of system
tubing . Symptoms of total leakage of refrigerant are mainly as follows: the compressor can be
started easily (if there is no damage to the compressor parts) and its operating current becomes low,
its gas suction pressure is high and discharge pressure is lower, the gas discharge tube feels rather
cold, no sound of gas eruption from the liquid in the evaporator can be
confused .Generally speaking ,you can make a judgment based on the frost formed on the
evaporator .If the frost does not cover the evaporator , and moreover ,it is loosely formed ,you can
make a judgment that the deterioration of refrigerating effect is due to the accumulation of
refrigerating oil left in the evaporator tubing in case no other troubles have been found . To clear off
refrigerating oil left in the evaporator, dismantle the evaporator, purge it thoroughly and then dry it .In
case it is difficult to dismantle it, charge
refrigerant from the evaporator inlet to wash it several times ,then purge and dry it with nitrogen .
7) Flowing obstructed in refrigerating system
Analysis of Trouble
Because the refrigerating system was originally not purged thoroughly ,some of the filter screen
meshes have been clogged by dirt accumulated in the filter after using it for a certain time of
period ,thus resulting in a decrease in flow rate ,and hence a poorer refrigerating effect . The
abnormal phenomena caused by this kind of slight clogging in the system are as follows: the gas
discharge pressure is lower, the temperature of discharged gas drops down, the position clogged
has a temperature lower than that in normal conditions and for a severe clogging ,even dew
condensation as frosting may appear .
Remedy
Purge the tubing, and after replacing the dry filter with a new one or clearing it thoroughly, recharge
the system with refrigerant and seal the charging port .
B. No Refrigerating
The phenomenon that the compressor runs normally, but refrigerator temperature does not drop
down is called "no refrigerating". There are many causes for this trouble and it is relatively
complicated, too. In servicing, special attention to finding direct causes for this phenomenon .Three
main potential causes for this trouble are analyzed below:
1) All refrigerant in the system has leaked out
Analysis of Trouble
Leak points in the refrigerating system have not been found and repaired timely, thus resulting in the
total escape of refrigerant .There are two kinds of leakage:
I) slow leakage for instance, when we want to use a refrigerator that has been put out of quite a
long time, we find the leakage of refrigerant, or in the course of its operation, we have found that the
refrigerator is gradually becoming not so cold and finally no refrigerating cab be achieved ;
ii) fast leakage in that case, all the refrigerant will escape swiftly due to abrupt rupture of system
tubing . Symptoms of total leakage of refrigerant are mainly as follows: the compressor can be
started easily (if there is no damage to the compressor parts) and its operating current becomes low,
its gas suction pressure is high and discharge pressure is lower, the gas discharge tube feels rather
cold, no sound of gas eruption from the liquid in the evaporator can be
heard, and no will gush out of
the process tube if you cut it open after shutdown.
Remedy
Check the whole machine, particularly those locations which are liable to leak .After leak points have
been found, repair them or replace them with new parts according to specific circumstances, then
Remedy
Check the whole machine, particularly those locations which are liable to leak .After leak points have
been found, repair them or replace them with new parts according to specific circumstances, then
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