🔍 Key Concepts

• Thermal expansion valve (TXV) function in a refrigeration system • Normal vs. abnormal sounds at the TXV (steady hiss vs. no sound vs. intermittent flow noise) • Relationship between refrigerant state (liquid vs. mixture vs. starved) and what reaches the evaporator

💭 Think About

• Think about what the TXV is supposed to do to the refrigerant before it enters the evaporator. Should it deliver pure liquid, pure vapor, or a mixture? • What condition would most likely create a continual, steady hissing sound: normal throttling action, a mechanical defect, low refrigerant charge, or solid liquid with no flashing? • If 100% liquid refrigerant were passing through to the evaporator, what kind of sound or temperature effect would you expect at the valve and at the evaporator inlet?

✅ Before You Answer

• Review how a pressure drop across the TXV causes refrigerant to flash (partly vaporize) and how that typically sounds • Confirm what "starved" vs. "flooded" evaporator conditions sound and look like (frosting, sweating, temperature differences) • Be sure you know the TXV’s normal operating indication in textbooks: what do they say about a continuous hissing noise under proper conditions?