Which HVAC component reduces refrigerant pressure and temperature?

• A. Expansion device
• B. Evaporator
• C. Condenser
• D. Compressor

Answer: (A)

Understanding how the refrigerant cools the space relies on how its pressure and temperature are controlled in the cycle. The component that lowers both pressure and temperature is the expansion device. It restricts the high-pressure liquid coming from the condenser, causing a rapid drop in pressure. As a result, the refrigerant exits as a low-pressure, low-temperature mixture of liquid and vapor. This cold refrigerant then enters the evaporator, where it absorbs heat from the surroundings and boils off, continuing the cycle. The other components don’t reduce pressure themselves: the compressor raises pressure and temperature, the condenser rejects heat at high pressure while condensing, and the evaporator is where heat absorption occurs, not where the pressure drop happens.