Question 128Refrigeration & AC - 1st Asst/Chief

The correct answer is C) thermal expansion valve. The thermal expansion valve is responsible for maintaining constant superheat at the evaporator coil outlet of a refrigeration system. It does this by automatically adjusting the flow of refrigerant into the evaporator based on the temperature and pressure changes in the system. As the refrigerant evaporates in the coil, the thermal expansion valve senses the resulting superheat and adjusts the refrigerant flow accordingly to keep the superheat at a constant level. The other options are incorrect because: A) a king valve is used to isolate a compressor, B) a low-pressure cutout switch shuts down the system at low pressure, and D) a solenoid valve opens and closes to control refrigerant flow, but does not maintain constant superheat.