🔍 Key Concepts

• Refrigeration cycle pressures: what happens to suction (low side) and discharge (high side) when refrigerant flow is restricted before the expansion valve • Function of the thermostatic expansion valve (TXV/TEV): it meters liquid refrigerant into the evaporator based on superheat at the outlet • Causes and effects of restrictions at the expansion valve inlet (dirt, wax, foreign matter vs. ice)

💭 Think About

• If less liquid refrigerant can reach the expansion valve because of a small obstruction, what happens to the amount of refrigerant entering the evaporator, and how does that affect suction pressure? • Would a restriction on the liquid line before the expansion valve tend to increase, decrease, or have little effect on discharge pressure from the compressor? Why? • Are expansion valves normally designed to "pass" foreign particles safely, or are filters/strainers and driers used to prevent that? What does that tell you about choices C and D?

✅ Before You Answer

• Think about whether the evaporator is being starved or flooded with refrigerant when the inlet to the TEV is partially blocked. • Consider how a starved evaporator affects the compressor suction pressure seen at the low side gauge. • Evaluate the statements in C and D: do real systems rely on the TEV to pass particles or on filters/driers to keep them out, and is ice really the only possible cause of a restriction?