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14
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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evacuate the system and finally charge refrigerant.
2) Refrigerating system has been clogged
a) Clogged with Ice
Analysis of Trouble
The dryness treatment for the major parts in the refrigerating system has been performed improperly,
the effect of air purging for the whole system is not good, or the water content in the refrigerant is out
of standard, all these will cause the expansion valve to be clogged with ice .The symptom for this
trouble are as follows :the refrigerator sometimes can refrigerate and sometimes cannot :the
refrigerator compartment works normally at the beginning, but after working for a certain period of
2) Refrigerating system has been clogged
a) Clogged with Ice
Analysis of Trouble
The dryness treatment for the major parts in the refrigerating system has been performed improperly,
the effect of air purging for the whole system is not good, or the water content in the refrigerant is out
of standard, all these will cause the expansion valve to be clogged with ice .The symptom for this
trouble are as follows :the refrigerator sometimes can refrigerate and sometimes cannot :the
refrigerator compartment works normally at the beginning, but after working for a certain period of
time, frosting begins at the clogged position, evaporation temperature reaches below 0°c, water
will accumulate at the narrow part of the capillary and clog it gradually, then frost begins to melt at
the evaporator, no gas flowing sound can be heard, and the gas suction pressure assumes a state
of vacuum .Note that these phenomena will appear intermittently; sometimes, the refrigerator works
well, and sometimes not well .In order to determine whether it is clogged with ice, heat the
suspicious points with hot water to make ice melt, and after a while if a gas flowing sound resulting
from an abrupt gush is heard and the gas suction pressure rises as well, it can be confirmed that the
trouble is caused by ice clogging.
Remedy If there is too much moisture in the refrigerating system, it is advisable to release the
refrigerant, purge the tubing with nitrogen, and then charge the system with the filtered refrigerant.
However, the commonly adopted method is to connect a filter with moisture absorbers (such as
silica-gel, anhydrous calcium chloride) to the refrigerating system so as to filter out the moisture from
the system, then replace the filter, evacuate it again and finally charge the system with refrigerant.
b) Clogged with dirt in capillary Analysis of Trouble
The capillary inlet is a place where coarse-grained dirt or refrigerant oil in the system will tend to
settle down and clog it. In case considerable dirt accumulates there, the whole filter screen may be
blocked totally, making the refrigerant unable to go through. Clogging with dirt exhibits the same
symptoms as that with ice, namely, higher gas suction pressure, lower temperature of discharged
gas, and no gas flowing sound from the evaporator. The difference between the both is as follows: if
the clogging is caused by dirt, tapping the suspicious clogged point (generally in the capillary or the
connection joint of the filter) may cause the refrigerant to flow through partially, resulting in some
corresponding change, whereas in that case if you heat it with a hot towel, no reaction will happen,
no flowing sound can be heard, moreover, there is no periodic change. After rejecting the possibility
of ice clogging, it can be generally considered as the clogging due to dirt .
Remedy Dismantle the system, remove the dry filter from it, purge the tubing with nitrogen, install a
new filter, then evacuate it and finally charge it with refrigerant.
C) Clogging in filter Analysis of Trouble
Total clogging of a filter is rarely to occur. This trouble is mostly caused by the paste-like matter
formed from the substances filled into the system or other dust after the refrigerator has been used
for a longer time, or by the dirt accumulated gradually inside the filter. Sometimes, tapping the filter
the evaporator, no gas flowing sound can be heard, and the gas suction pressure assumes a state
of vacuum .Note that these phenomena will appear intermittently; sometimes, the refrigerator works
well, and sometimes not well .In order to determine whether it is clogged with ice, heat the
suspicious points with hot water to make ice melt, and after a while if a gas flowing sound resulting
from an abrupt gush is heard and the gas suction pressure rises as well, it can be confirmed that the
trouble is caused by ice clogging.
Remedy If there is too much moisture in the refrigerating system, it is advisable to release the
refrigerant, purge the tubing with nitrogen, and then charge the system with the filtered refrigerant.
However, the commonly adopted method is to connect a filter with moisture absorbers (such as
silica-gel, anhydrous calcium chloride) to the refrigerating system so as to filter out the moisture from
the system, then replace the filter, evacuate it again and finally charge the system with refrigerant.
b) Clogged with dirt in capillary Analysis of Trouble
The capillary inlet is a place where coarse-grained dirt or refrigerant oil in the system will tend to
settle down and clog it. In case considerable dirt accumulates there, the whole filter screen may be
blocked totally, making the refrigerant unable to go through. Clogging with dirt exhibits the same
symptoms as that with ice, namely, higher gas suction pressure, lower temperature of discharged
gas, and no gas flowing sound from the evaporator. The difference between the both is as follows: if
the clogging is caused by dirt, tapping the suspicious clogged point (generally in the capillary or the
connection joint of the filter) may cause the refrigerant to flow through partially, resulting in some
corresponding change, whereas in that case if you heat it with a hot towel, no reaction will happen,
no flowing sound can be heard, moreover, there is no periodic change. After rejecting the possibility
of ice clogging, it can be generally considered as the clogging due to dirt .
Remedy Dismantle the system, remove the dry filter from it, purge the tubing with nitrogen, install a
new filter, then evacuate it and finally charge it with refrigerant.
C) Clogging in filter Analysis of Trouble
Total clogging of a filter is rarely to occur. This trouble is mostly caused by the paste-like matter
formed from the substances filled into the system or other dust after the refrigerator has been used
for a longer time, or by the dirt accumulated gradually inside the filter. Sometimes, tapping the filter
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