Top Reasons Why Refrigeration Compressors Fail.

 The lubricating oil of the compressor, in some types of compressors, is pumped together with the refrigerant. If there is no return of this oil to the compressor, the lack of oil will cause the compressor to wear out quickly and its locking may occur.  The lubricating oil may react chemically with the refrigerant. This occurs when refrigerant and oil are chemically compatible, such as R-134a refrigerant and mineral oil. The oil may be "fine", i.e., has its viscosity reduced, which may also lead to the failure cited above.  The chemical reaction of the oil with the refrigerant also results in the formation of acids, which in turn chemically attack (react with) various compressor materials, such as the enamel covering the wiring of the electric motor, the rubbers, plastics and metals used On the compressor body, etc. Obviously, this chemical attack wears out and destroys the parts, which can lead to failures.  Moisture (water) can also react with the refrigerants and oils, forming acids, with the consequences described above. Hence the importance of a correct and effective dehydration of the system (obtained through the evacuation process).  The intake of liquid refrigerant in the compressor can also cause faults. If the liquid is sucked by the compressor pump, it can reach the suction valves, causing an erosion (called liquid stroke) that eventually leads to valve breakage, rendering the compressor ineffective or even arresting it.  When the compressor is subjected to high pressure differentials (difference between the suction pressure and the compressor discharge pressure), it needs to expend much more energy to pump the refrigerant. When this occurs, the electric motor that moves the compressor begins to consume much more electric energy, which is translated by the increase of the current in the compressor. For this there is the overload protection relay: if the current in the compressor increases greatly, this relay automatically shuts off the compressor. However, in case of relay failure, or in the case of using an inadequate (over-sized) relay, the relay may not turn off the compressor, which may lead to an electric motor burnout (motor wiring overheats, enamel Protector around the wire is destroyed, and the wiring may short circuit).  When the compressor discharge temperature is too high, the compressor as a whole overheats, which increases the possibility of chemical reactions between moisture, refrigerant and lubricating oils, and may also cause degradation of the electric motor materials. Lead to burning.  When the compressor is switched off, liquid refrigerant may migrate from the suction line to the compressor housing or crankcase. This liquid refrigerant mixes with the oil. This can cause the oil to lose part of its lubricating capacity, becoming "thin", which, when the compressor is reconnected, will end up causing more wear on the compressor.