Logic LUL55S10 User manual

1
REFRIGERATOR
Service Manual
Models: LUL55S10
Features
●Energy efficiency
●Low noise operation
●Thick insulation for energy efficiency

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CONTENT
CONTENT
1. Content1
2. Product code illumination and Series Introduction2
3. Specifications3
4. Safety precautions4
5. Function Schedule 7
6. System Flow Chart8
7. Circuit Diagram9
8. Maintenance Service and Trouble Shooting10
9. Exploded View30
10. List of Parts31

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Specifications
Specifications
Models LUL55S10
Net capacity (L) 131
Color Silver
Power Supply
(V/Hz) 220~/50
Rated Input Power
(W) 63
Power Consumption
(kW.·h/24h) 0.415
Net Weight
(kg) 28.5
Gross Weight
(kg) 31.5
Unit Dimension
(D*W*H)
(mm) 570*544*845
Packing Dimension
(D*W*H)
(mm) 560*535*885
Container Quantity
40'HQ
(PCS) 238

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Safety precautions
Safety precautions
This appliance uses 220-240V~50Hz AC
for power supply.
Failure in operation and damage to the control
panel, thermostat or the compressor will occur if
voltage is outside the range 187-242V, unless a
regulator with a capacity of 750W or higher is
installed.
It is required to use separate, special
outlet with securely grounding.
The power cable of this appliance is fitted with
three-core (grounding) plug complying with
three-core (grounding) outlet. In no case, should
the third plug pin (grounding) of the power cable
be cut or removed.
Do not damage power cable
Be sure not to pull out the plug of the appliance
by drawing the power cable. Be sure to directly
pull it of the outlet by firmly grasping the plug.
Do not move the appliance by pressing the
power cable, or tread on it.
When moving the appliance from wall, be careful
not to roll or damage power cable.
In case of damaged power cable
If the power cable or plug was damaged, it
is prohibited to continue using it. In this
case, it must be replaced by technician or
authorized service personnel.
When there is leakage of inflammable
gas:
Never try to pull out or insert any power
plug for any electrical appliance such as
refrigerator.
Electricity plug must be cut off for below
following situations:
-Pull out power plug prior to cleaning or repairing;
-When replacing damaged lamp, it is required to
pull out power plug to prevent electrical shock.

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Safety precautions
Safety precautions
It is absolutely prohibited to put hazardous
inflammable or explosive articles, strong
corrosive acid, alkali, etc inside the
appliance.
Do not keep medicine, vaccine, or chemical
agent in the appliance. This refrigerator is for
household use, which cannot store items
with strict requirement for temperature.
Do not store or use gasoline or other
flammable article in the vicinity of the
refrigerator to avoid fire.
Do not place any electrical plugs, regulators
or microwaves on top of the refrigerator. Do
not use electric appliances (except those
allowed by manufacturer) in side the
refrigerator.
Do not play by hanging on its door, to
prevent tilting the door or toppling the
refrigerator to hurt person.
Do not place heavy or unstable articles or
water containers on top of the refrigerator

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Safety precautions
Safety precautions
When the refrigerator has started running,
take care not to touch the cold surface of the
freezer compartment with hand, especially
with wet hand. Otherwise, your skin may be
to be stuck on the cold surface.
Do not spray water onto the refrigerator, or
place it in wet area where water can be
easily splashed, so as to avoid influencing
the electric insulation performance of the
appliance.
It is strictly prohibited to privately dismantle
or change the appliance component. For the
repair of refrigerator, it can be carried out by
professional only.
Do not put the bottled beer or beverage in
the freezer compartment to prevent frost
crack.
In case of unstable power supply or during
cleaning, it is required to pull out the power
plug, and to wait at least 5 minutes for
switchingon it again to prevent damaging its
compressor by continuous starting.
When door, or door gasket of the appliance
is to be dismantled, be careful of children
play inside to avoid any accident.

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Function Schedule
Function Schedule
●Energy efficiency
●Low noise operation
●Thick insulation for energy efficiency

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System Flow Chart
System Flow Chart
1 Schematic diagram of System Flow Chart
1. Compressor
2. Condenser
3. Dry filter
4. Capillary tube
5. Evaporator
2 Brief Description of System Flow Chart
Model LUL55S10 is a direct cooling single-system refrigerator.
When the refrigerator is just powered on, the refrigerant flows in the sequence:
1->2->3->4->5>1

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Circuit Diagram
Circuit Diagram
1Schematic Circuit Diagram
2 Brief Description of Control Principle
Model LUL55S10 is a direct cooling single-system larder. A mechanical type of all the
control is generally adopted. The thermostat directly controls the start and stop of
compressor, and hence the refrigerator temperature.

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Maintenance Service and Trouble Shooting
Maintenance Service and Trouble Shooting
1. No cooling
NO
YES
NO
YES
When charging refrigerant, we
must notice to make refrigerant
No cooling
If compressor can
run after it stop to
run five minutes
and
give power.
Check and repair according to
the section of "the compressor
does not work".
If compressor can
run naturally and
temperature raising
of condenser is very
Refrigerant leak. Check, repair
and charge refrigerant again.
Block by ice or dirty things, change
filter and change refrigerant again.

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true.
Maintenance Service and Trouble Shooting
2 The compressor doesn't stop
YES
NO
YES
NO
YES
NO
YES
Compressor does not stop
Is refrigerator
cooling?
Check and repair according to
the section of "No cooling".
Is cooling capacity
insufficient?
Check and repair according to
the section of "Cooling capacity
is insufficient".
1 The thermostat was set at the
coldest position.
2 The ambient temperature is
very high or the refrigerator is
near by heat resource.
3 The door was opened too
many times or there is more
fresh food inside.
Adjust and instruct
consumer how to use.
Check and repair the main
control panel

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Maintenance Service and Trouble Shooting
3 Cooling capacity is insufficient
YES
NO
YES YES NO
YES
Cooling capacity is insufficient
Adjust and instruct
consumer how to use
Repair
Is the ambient
temperature
low
t
han
16
°
C
Does the
refrigerant leak
slowly?
Check the
thermostat is
correct?

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Maintenance Service and Trouble Shooting
4 The compressor doesn't work
YES
NO
NO
YES
YES
NO
YES
YES
NO
YES
NO
YES
The compressor doesn't work.
Is the interior
light on when
door is opened
?
Is the power of
220V output?
Do the compressor
have 220V output?
Is the ambient
temperature
low
t
han
16
°
C
Check the power
source and power
Check the
thermostat is
correct?
Repair
Adjust and instruct
consumer how to use
Check and repair the
control panel.
Check all cords and
power cords

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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.
Check and repair compressor
and accessory

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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 powerconsumption ,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 whether it is suitable for placing a refrigerator .
f) layer .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.
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

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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", 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 itsounds 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°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

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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 .
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 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
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

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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 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 refrigeratingefficiency .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 .

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Remedy
Turn the refrigerator off ,and make preparations for defrosting ,open therefrigerator 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 ,ifthere 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
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 no frost (or only a little frost )
appears on the evaporator ,and the 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 :

20
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 escapeswiftly 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 beheard ,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 liableto leak .After leak
points have been found ,repair them or replace them with new parts according to specific
circumstances ,then 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 ofstandard ,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 whetherit 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