It is assumed that, following a careful analysis of the parts of a failed compressor, the maintenance technician should be able to find out and explain the true cause of the failure, but unfortunately this is not always possible. In reality, the time available, the space around the machine, the freedom to disassemble to proceed with the analysis, are not always sufficient to establish the origin of the faults, and furthermore certain particular breakages of compressors do not allow to ascertain the cause before the failure.

When trying to clean the broken parts thoroughly sometimes causes carbon residues, paint, etc. are such that one wonders even how the compressor could have operated up to that moment.

In these situations, all we can do is examine the set of possible causes, which we have explained above, to conclude that probably many joint factors have led to the failure. The conditions that give rise to a very serious failure have probably developed in an extensive and complex way. Keeping in mind all the various possibilities of problems, failures, short circuits, we can try to avoid that the same sequence of conditions that gave rise to the first failure can occur.

During the necessary cleaning operations, it is good to check the details of the electrical components, such as - for example - the sections of the power cables, the conditions of the contacts, terminals, etc. It should also be checked that the motor safety devices are not short-circuited and that the pressure switches are correctly adjusted and wired, and also check that the bulb of the thermostatic valve is installed properly and that the valve itself is in good condition.

These are simple and obvious details, but which can sometimes be overlooked in the haste to install and start the system.

Finally, it must be ensured that the system is perfectly clean and carefully reassembled. When it is started again, the pressures and temperatures should be checked: these data can be used for a conclusive determination about the causes of the initial failure.

After the occurrence of a compressor engine failure or a failure caused by the presence of contaminants in the cooling circuit, it is of primary importance to carry out a thorough cleaning of the entire system. 

The reliability and durability of the repaired compressor or the new compressor depend on the care with which this cleaning was performed.

The suction and discharge lines near the compressor must be checked; if they contain combustion products or other contaminants following an engine failure, before installing the compressor, they must be cleaned with appropriate products.

Note: Products containing chlorine should not be used.

When installing a compressor in a system that has suffered an electrical fault, it is advisable to insert a filter drier of adequate size in the suction line.

After the leak test has been completed and the pressure restored, the filter cartridge on the line is replaced and the vacuum is made at an absolute pressure of 1 mm Hg. 

The vacuum is broken by pumping dry nitrogen and then the absolute pressure of 1 mm Hg is restored again. 

The system is left in these conditions for 12 hours; if after this period of time the vacuum remains unchanged this means that the system is sealed and dehydrated and the refrigerant can be charged.