What is a main cause of liquid slugging in a system?

Liquid slugging occurs when a compressor draws in liquid instead of the intended vapor. This primarily happens due to the presence of lubricating oil being carried along with the refrigerant in the suction line. When the compressor draws in this mixture, the liquid refrigerant, along with oil, can cause mechanical damage to the compressor, as it is not designed to compress liquids.

The presence of lubricating oil can come from various sources within the system, such as leaks or poor oil return from the evaporator. This issue often arises in systems where oil is not adequately separated from the refrigerant before entering the compressor. Therefore, the main cause of liquid slugging in this scenario is the compressor drawing in lubricating oil, which can lead to significant operational issues and damage.