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Maintenance Service and Troubleshooting
4. Clogged filter
Analysis of Problem
A completely clogged filter rarely happens. When this problem does occur, it
is usually caused by a buildup of paste-like matter, dust, or dirt on the filter after
the refrigerator has been in use for a long period of time. Sometimes, tapping the
filter may remove some of the blockage. When the filter is clogged, its
temperature will be cooler than normal.
Solution
The same as prescribed in the “Refrigerating system clogged with dirt”
section.
5. Broken gas suction and discharge valve blocks
Analysis of Problem
The compressor works by opening and closing the gas suction and discharge
valves in order to draw in and discharge the refrigerant. If the valve block is
broken, the refrigerant cannot be discharged, preventing refrigeration.
Solution
It can be difficult to differentiate this problem from others because they often
share similar symptoms. When repairing, listen attentively for any abnormal
sound(s) coming from the compressor—sometimes the broken pieces of valve
block may strike against the cylinder. Next, feel the compressor casing to
determine if it is too hot. Then, with pressure gauges, measure the pressures at
the high and low pressure ports of the compressor. If the gas suction valve block
is broken, the suction pressure will be extremely high and its gauge pointer will
swing violently. If the gas discharge valve block is broken, the discharge
pressure will be extremely high and its gauge pointer will also swing drastically.
In both cases, stop the compressor at once, and, if possible, open the cylinder
cover to check the valve block, and then repair or replace.
C. Compressor Suddenly Stops
Often when the compressor suddenly stops during operation, the gas suction
pressure and/or discharge pressure have exceeded their respective prescribed
ranges. When this occurs, the pressure-operated protective relay automatically
shuts off the compressor. Below are some of the common reasons for high gas
discharge pressure and low suction pressure.
1. Stoppage due to excessively high gas discharge pressure
1a. Excess refrigerant
Analysis of Problem
Loose frost and poor refrigerating effect may occur if excessive refrigerant is
charged into the system. Excessive refrigerant will occupy additional space in the
evaporator, which will reduce its heat dissipating area, and “liquid striking”
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