A partially clogged capillary tube can cause which evaporator condition?

• A. Overcharged system
• B. A starved evaporator
• C. Increased superheat
• D. No effect

Answer: (B)

When the capillary tube is partially clogged, the amount of refrigerant that reaches the evaporator is reduced. The evaporator depends on a steady flow of liquid refrigerant to absorb heat; with restricted flow, it doesn’t receive enough liquid, so it operates in a starved state. This means cooling capacity drops and the evaporator is effectively short of refrigerant, which is the defining condition. A partially clogged metering device doesn’t simply cause no effect, nor does it describe an overcharged condition; increased superheat can occur as a consequence, but the clear, primary issue is that the evaporator becomes starved of refrigerant.