🔍 Key Concepts

• Thermal expansion valve (TXV) operation: how bulb temperature affects valve opening • Relationship between refrigerant flow, superheat, and frosting of the suction line • What conditions inside the TXV (too much vs. too little refrigerant flow) will cause liquid refrigerant to reach the compressor suction line

💭 Think About

• Which problem with the TXV or its sensing bulb would cause the valve to overfeed refrigerant instead of starving the evaporator? • If the suction line is heavily frosted, does that suggest too much liquid refrigerant leaving the evaporator, or not enough? • For each option, ask: does this condition tend to make the valve stay more open or more closed, and what effect would that have on suction line temperature?

✅ Before You Answer

• For each answer choice, decide whether it would cause overfeeding (low superheat, possible flooding and frosting) or underfeeding (high superheat, warm suction line) • Think about where the sensing bulb must be and how it must be attached to correctly sense suction line temperature • Consider whether loss of power element charge or a stuck-closed needle would more likely cause starvation (warm suction, no frost) rather than heavy frosting