Magic Chef MCSF-5585BSS, Instruction Manual

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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 judgement 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 thegas 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
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 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