🔍 Key Concepts

• Thermal expansion valve (TXV) sensing and equalizing functions • Difference between refrigerant pressure drop in the evaporator vs air pressure drop across the coil • How a TXV maintains correct superheat when inlet and outlet pressures are not the same

💭 Think About

• Ask yourself: Does an externally equalized TXV care about the air side of the coil or the refrigerant side of the system? • Think about what happens if there is a significant pressure drop between the TXV outlet and the point where superheat is actually being measured. • Which situation would cause the TXV to ‘see’ the wrong pressure if it were only internally equalized?

✅ Before You Answer

• Verify whether TXV equalizer lines connect to the refrigerant line or to the air duct. • Check which choices refer to refrigerant pressure and which refer to air pressure. • Confirm that the condition involves a significant pressure drop along the evaporator where the bulb senses temperature at the outlet.