What is the most likely cause of significant drops in crankcase and compressor discharge temperature along with high suction line pressure in a refrigerating unit?

The scenario described involves significant drops in crankcase and compressor discharge temperature, alongside high suction line pressure, which signifies an abnormal functioning within the refrigerating unit. An expansion valve that is open too wide allows the refrigerant to enter the evaporator at a rate higher than it can absorb heat. This can lead to insufficient cooling of the gas in the crankcase and compressor, resulting in lower temperatures in those areas.

When the expansion valve is excessively open, it disrupts the balance necessary for proper refrigeration cycle operation. Consequently, this can lead to an accumulation of refrigerant and a rise in suction line pressure, as the refrigerant is not completely evaporating in the evaporator coil due to the excessive flow. The combined effect of lower temperatures in the crankcase and compressor and high suction pressure is consistent with this malfunction, highlighting the critical role of the expansion valve in maintaining proper system performance.

Other possibilities, such as a faulty thermostat, a leak in the evaporator coil, or a malfunctioning condenser fan, typically lead to different symptoms, such as inadequate cooling, increased compressor workload, or pressure imbalances that don’t align with the observed drops in temperatures and the simultaneous high suction line pressure. Thus, the situation indicates a specific malfunction pertaining to the expansion