🔍 Key Concepts

• Thermal expansion valve (TXV) sensing bulb function and location • Relationship between evaporator outlet temperature and superheat • How changes in load (box temperature or condenser conditions) affect evaporator pressure and bulb temperature

💭 Think About

• Think about what the sensing bulb on a thermal expansion valve is actually measuring. How does that signal tell the valve to open more or close more? • If the refrigerant leaving the evaporator gets warmer or colder, what does that say about the amount of liquid vs. vapor in the evaporator and the current superheat? • Which of the listed conditions would increase the sensed superheat at the evaporator outlet, causing the valve to move toward a more open position?

✅ Before You Answer

• Identify where the TXV sensing bulb is mounted (on the evaporator outlet line) and what variable it responds to (temperature related to superheat). • Decide which choice would increase superheat at the evaporator outlet, not just change box or condenser temperatures indirectly. • Verify that the condition you choose would make the bulb warmer relative to the evaporator pressure, which is what drives the valve toward a more open position.