What is the most likely cause of the changes observed in the DX system regarding the suction and compressor pressures and temperatures?

The most likely cause of the changes observed in the DX system concerning the suction and compressor pressures and temperatures is the loss of liquid feed supply to the evaporator. When the evaporator does not receive an adequate supply of liquid refrigerant, it leads to insufficient heat absorption in the evaporator coil. This can result in a drop in suction pressure and temperature because the compressor is not able to draw in the necessary vapor effectively.

Without sufficient liquid refrigerant entering the evaporator, the refrigerating cycle is disrupted. The evaporator will turn into a partially filled state, leading to reduced evaporation and corresponding changes in the pressures and temperatures measured at the compressor. Thus, this situation offers a clear and logical explanation for the observed operational deficiencies in the system, ultimately affecting overall efficiency. The focus on refrigerant flow and its impact on system performance underscores why identifying and correcting feed supply issues is critical in temperature and pressure management within a DX system.