Premium PFR70800M, Service Manual

Maintenance Service and Trouble Shooting   

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 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 Freezer sometimes 

can refrigerate and sometimes cannot :the Freezer 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

e

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 Freezer 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 

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