Nate Core Practice Test 2026 – Comprehensive Exam Prep

The role of an expansion valve in refrigeration is primarily to control the flow of refrigerant into the evaporator. This component is crucial for maintaining the efficiency and performance of the refrigeration system. When the refrigerant flows through the expansion valve, it experiences a drop in pressure, which causes it to expand and cool before entering the evaporator. This precise control of refrigerant flow ensures that the right amount of refrigerant is available for the evaporation process, allowing for optimal heat absorption from the surroundings. By managing how much refrigerant enters the evaporator, the expansion valve helps to maintain the necessary pressure and temperature for effective cooling.

Other choices, while related to refrigeration, don't accurately describe the function of an expansion valve. Increasing the pressure of the refrigerant is the job of the compressor, while warming refrigerant before it enters the compressor is not typical; rather, refrigerant needs to be in a vapor state before entering the compressor. Cooling the refrigerant is part of the function of the evaporator, not the expansion valve itself. Therefore, controlling the flow into the evaporator is the essential and defining role of the expansion valve.