Panasonic NR-BN30PGW / NR-BN30PGB / NR-BN30PS1 / NR-BN30QGW / NR-BN30QGB / NR-BN30QW1 / NR-BN30QS1 Service Manual ▷ View online
17
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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nay cause a passage for flowing, Touching it with your hand, you will feel that it is cooler compared
with its temperature in the normal state.
Remedy The same as described in the capillary clogging with dirt.
3) Troubles of Compressor
a) Breakage of gas suction and discharge valve blocks Analysis of Trouble
The compressor works by means of the opening and closing of gas suction valve and discharge
valve to suck and discharge the refrigerant. If the valve block is broken, the refrigerant can not be
discharged, and hence no refrigerating can be achieved.
Method for making judgment It is quite difficult to differentiate this trouble from others because they
often have similar symptoms. In repairing, firstly, hear attentively if there is some abnormal sound
coming from the compressor (sometimes, the broken pieces of valve block may strike against the
cylinder), and feel the compressor casing with your hand to ascertain whether it is too hot, this is
also helpful to the troubleshooting; secondly, measure the pressures at the high and low pressure
ports of the compressor with pressure gauges, if the gas suction valve block is broken, the suction
pressure gauge pointer will swing violently and the suction pressure is very high, whereas when the
gas discharge valve block is broken, the discharge pressure gauge pointer will swing drastically
and the discharge pressure is very high. In the both cases, stop the compressor at once, and if
technique is available, open the cylinder cover and check up the valve block, repair it, or replace it
with a new one,
C. Sudden stop of Compressor during Its Running
The cause of sudden stop of a compressor during its running is mostly that the gas suction pressure
and/or discharge pressure exceed their respective prescribed ranges, thus making a
pressure-operated protective relay shut off the power to the compressor and stop it. In the following
we discuss mainly the reasons for causing excessively high gas discharge pressure and low suction
pressure.
1) Stoppage due to excessively high gas discharge pressure
A) Too much refrigerant charged into the system
Analysis of Trouble
The phenomenon, such as loose frosting and poor refrigerating effect, may occur if excessive
refrigerant has been charged into the system. Superfluous refrigerant will occupy a certain space of
the evaporator, thus reduce its heat dissipating area, and the phenomenon of "liquid striking" may
occur, too. Meanwhile, dew or frost condensation may occur on the gas return tube, and the gas
discharge pressure will obviously rise, when it reaches the threshold value, the protective relay will
actuate and shut off the power supply to the compressor.
Remedy
Open the tubing, re-evacuate and then charge the system with a proper quantity of refrigerant.
b) Air left in the system
Analysis of Trouble
The residual air in the system will circulate together with the refrigerant in the system. The major
symptoms caused by this residual air is higher gas discharge pressure, higher discharged gas
temperature (the gas discharge tubing is considerably hot when you feel it with your hand), and
poorer refrigerating effect. Furthermore, the gas discharge pressure will exceed its normal value
with its temperature in the normal state.
Remedy The same as described in the capillary clogging with dirt.
3) Troubles of Compressor
a) Breakage of gas suction and discharge valve blocks Analysis of Trouble
The compressor works by means of the opening and closing of gas suction valve and discharge
valve to suck and discharge the refrigerant. If the valve block is broken, the refrigerant can not be
discharged, and hence no refrigerating can be achieved.
Method for making judgment It is quite difficult to differentiate this trouble from others because they
often have similar symptoms. In repairing, firstly, hear attentively if there is some abnormal sound
coming from the compressor (sometimes, the broken pieces of valve block may strike against the
cylinder), and feel the compressor casing with your hand to ascertain whether it is too hot, this is
also helpful to the troubleshooting; secondly, measure the pressures at the high and low pressure
ports of the compressor with pressure gauges, if the gas suction valve block is broken, the suction
pressure gauge pointer will swing violently and the suction pressure is very high, whereas when the
gas discharge valve block is broken, the discharge pressure gauge pointer will swing drastically
and the discharge pressure is very high. In the both cases, stop the compressor at once, and if
technique is available, open the cylinder cover and check up the valve block, repair it, or replace it
with a new one,
C. Sudden stop of Compressor during Its Running
The cause of sudden stop of a compressor during its running is mostly that the gas suction pressure
and/or discharge pressure exceed their respective prescribed ranges, thus making a
pressure-operated protective relay shut off the power to the compressor and stop it. In the following
we discuss mainly the reasons for causing excessively high gas discharge pressure and low suction
pressure.
1) Stoppage due to excessively high gas discharge pressure
A) Too much refrigerant charged into the system
Analysis of Trouble
The phenomenon, such as loose frosting and poor refrigerating effect, may occur if excessive
refrigerant has been charged into the system. Superfluous refrigerant will occupy a certain space of
the evaporator, thus reduce its heat dissipating area, and the phenomenon of "liquid striking" may
occur, too. Meanwhile, dew or frost condensation may occur on the gas return tube, and the gas
discharge pressure will obviously rise, when it reaches the threshold value, the protective relay will
actuate and shut off the power supply to the compressor.
Remedy
Open the tubing, re-evacuate and then charge the system with a proper quantity of refrigerant.
b) Air left in the system
Analysis of Trouble
The residual air in the system will circulate together with the refrigerant in the system. The major
symptoms caused by this residual air is higher gas discharge pressure, higher discharged gas
temperature (the gas discharge tubing is considerably hot when you feel it with your hand), and
poorer refrigerating effect. Furthermore, the gas discharge pressure will exceed its normal value
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when the compressor has run for a period not too long, thus making the protective relay actuate and
bring to a stoppage.
Remedy
Check up how the air has been left in the refrigerating system. Generally, there are two possibilities:
one is that the air has been sucked into the system when repairing due to carelessness, or it has not
been purged out totally when evacuating the system; the other is that there are leak points at the low
pressure end of the refrigerating system. Leak points appear mostly in those low temperature parts
or assemblies, because the evaporation temperature is lower for such low temperature devices,
especially at the low pressure end, it is easier for the air goes into the system. Once it has been
ascertained that air does exist in the system, you have to open the tubing, re-evacuate it and then
charge it with refrigerant.
2) Stoppage due to electric troubles
a) Thermostat is out of control Analysis of Trouble
In case the thermostat does not work in its good order or its temperature sensor has not been
installed properly, frequent stoppage is also likely to occur.
Remedy
Try to adjust the temperature sensor's position until the compressor can be started and stopped
normally. If this cannot be achieved, and the stoppage still occurs repeatedly, it is most likely that
the mechanical parts or contacts are out of order, disassemble the thermostat, make a thorough
checkup and repair it.
b) Overload of electric motor
Analysis of Trouble
Probably, too many things have been put into the refrigerator, and hence the thermal load exceeds
its refrigerating capacity ; or in case the power supply voltage drops considerably, the current
flowing through the motor will increase drastically making the thermal protector actuate and the fuse
blown, and hence the motor stops running. If the motor is still running continuously in such a case,
its windings will be burned out .
Remedy. Reduce the thermal load, pay attention to the variation in voltage of the power supply.
c) Abnormal thermal protection.
Analysis of Trouble
The compressor current is within its normal range, but the thermal protector actuates repeatedly.
Remedy
Replace the thermal protector with a new one.
3) Sudden stoppage due to other causes
Normal Stoppage
Start and stop of the compressor is generally controlled by a thermostat . When the temperature in
the refrigerator reaches its desired value, the thermostat will shut down the compressor
automatically. Never take this normal operation as a trouble, care should be taken to differentiate it
from other real troubles in servicing.
bring to a stoppage.
Remedy
Check up how the air has been left in the refrigerating system. Generally, there are two possibilities:
one is that the air has been sucked into the system when repairing due to carelessness, or it has not
been purged out totally when evacuating the system; the other is that there are leak points at the low
pressure end of the refrigerating system. Leak points appear mostly in those low temperature parts
or assemblies, because the evaporation temperature is lower for such low temperature devices,
especially at the low pressure end, it is easier for the air goes into the system. Once it has been
ascertained that air does exist in the system, you have to open the tubing, re-evacuate it and then
charge it with refrigerant.
2) Stoppage due to electric troubles
a) Thermostat is out of control Analysis of Trouble
In case the thermostat does not work in its good order or its temperature sensor has not been
installed properly, frequent stoppage is also likely to occur.
Remedy
Try to adjust the temperature sensor's position until the compressor can be started and stopped
normally. If this cannot be achieved, and the stoppage still occurs repeatedly, it is most likely that
the mechanical parts or contacts are out of order, disassemble the thermostat, make a thorough
checkup and repair it.
b) Overload of electric motor
Analysis of Trouble
Probably, too many things have been put into the refrigerator, and hence the thermal load exceeds
its refrigerating capacity ; or in case the power supply voltage drops considerably, the current
flowing through the motor will increase drastically making the thermal protector actuate and the fuse
blown, and hence the motor stops running. If the motor is still running continuously in such a case,
its windings will be burned out .
Remedy. Reduce the thermal load, pay attention to the variation in voltage of the power supply.
c) Abnormal thermal protection.
Analysis of Trouble
The compressor current is within its normal range, but the thermal protector actuates repeatedly.
Remedy
Replace the thermal protector with a new one.
3) Sudden stoppage due to other causes
Normal Stoppage
Start and stop of the compressor is generally controlled by a thermostat . When the temperature in
the refrigerator reaches its desired value, the thermostat will shut down the compressor
automatically. Never take this normal operation as a trouble, care should be taken to differentiate it
from other real troubles in servicing.
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D. Compressor won't start
In case the compressor cannot be started, you must find out the origins of this trouble through
checkup step by step, because probably there are many causes, including those electrical and
mechanical.
1) Inspect the power supply to see whether it is connected to the compressor circuit.
Analysis of Trouble
In case the compressor cannot be started, this will generally exhibit in the power supply circuit, for
instance, power failure, poor contact of switch, and blown fuse. Make a comprehensive analysis of
these phenomena, fine out its real cause and take correct measures to remove this trouble.
Remedy
a) Check the input power circuit to see whether where is voltage of the power supply, namely, the
circuit which is connected to the knife switch. This can be determined with an avometer or a test
pencil. If a blown fuse is found, ascertain and remove its cause, then replace it with a new one of the
same specifications.
b) Check the compressor accessories, including its thermal protector and relay. In case the thermal
protector is damaged, the compressor cannot be powered on. If the relay is out of order, the motor
will not run and hum sound can be heard from it after the compressor is turned on, in that case, shut
it down immediately, otherwise, the motor windings will be
burned out in case this condition lasts longer.
c) Check the relay contacts and plugs to see if they are perfect and work reliably. Poor contact may
cause the motor not running or humming.
2) Check the circuit voltage to see whether it is normal.
Analysis of trouble
If the circuit voltage is obviously lower than its rated value, it will be difficult to start the motor, and a
hum sound can be heard from it.
Remedy
Measure the voltage with a voltmeter, if it is really too low, give directions to the user for buying a
stabilizer so as to step up the voltage, thus normal operation can be achieved.
3) Check the thermal relay to see whether its contacts are closed.
Analysis of Trouble
The contacts of thermal relay sometimes may be open due to the leakage of temperature sensing
agent from the temperature sensor.
Remedy
Remove the relay cover to check up its contacts, if they are open, this means that the original setting
is not properly set or temperature sensing agent has leaked out of the temperature sensor. Try to
turn the adjusting stem of this value in the direction of the lower temperature graduation, then check
the contacts to see whether they are closed. If they are still not closed, dismantle the temperature
sensing disc and then immerse it into warm water to see whether the contacts actuate, if not, it can
be preliminarily determine that temperature sensing agent has leaked out, and it must be replaced
with a new thermostat.
In case the compressor cannot be started, you must find out the origins of this trouble through
checkup step by step, because probably there are many causes, including those electrical and
mechanical.
1) Inspect the power supply to see whether it is connected to the compressor circuit.
Analysis of Trouble
In case the compressor cannot be started, this will generally exhibit in the power supply circuit, for
instance, power failure, poor contact of switch, and blown fuse. Make a comprehensive analysis of
these phenomena, fine out its real cause and take correct measures to remove this trouble.
Remedy
a) Check the input power circuit to see whether where is voltage of the power supply, namely, the
circuit which is connected to the knife switch. This can be determined with an avometer or a test
pencil. If a blown fuse is found, ascertain and remove its cause, then replace it with a new one of the
same specifications.
b) Check the compressor accessories, including its thermal protector and relay. In case the thermal
protector is damaged, the compressor cannot be powered on. If the relay is out of order, the motor
will not run and hum sound can be heard from it after the compressor is turned on, in that case, shut
it down immediately, otherwise, the motor windings will be
burned out in case this condition lasts longer.
c) Check the relay contacts and plugs to see if they are perfect and work reliably. Poor contact may
cause the motor not running or humming.
2) Check the circuit voltage to see whether it is normal.
Analysis of trouble
If the circuit voltage is obviously lower than its rated value, it will be difficult to start the motor, and a
hum sound can be heard from it.
Remedy
Measure the voltage with a voltmeter, if it is really too low, give directions to the user for buying a
stabilizer so as to step up the voltage, thus normal operation can be achieved.
3) Check the thermal relay to see whether its contacts are closed.
Analysis of Trouble
The contacts of thermal relay sometimes may be open due to the leakage of temperature sensing
agent from the temperature sensor.
Remedy
Remove the relay cover to check up its contacts, if they are open, this means that the original setting
is not properly set or temperature sensing agent has leaked out of the temperature sensor. Try to
turn the adjusting stem of this value in the direction of the lower temperature graduation, then check
the contacts to see whether they are closed. If they are still not closed, dismantle the temperature
sensing disc and then immerse it into warm water to see whether the contacts actuate, if not, it can
be preliminarily determine that temperature sensing agent has leaked out, and it must be replaced
with a new thermostat.
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