During troubleshooting, if the superheat value of the refrigerant leaving an evaporator is higher than normal:

• A. The evaporator is starved for refrigerant.
• B. The refrigerant charge is excessive.
• C. The condenser is oversized.
• D. The metering device is stuck closed.

Answer: (A)

High superheat at the evaporator outlet means the evaporator isn’t getting enough liquid refrigerant to fully evaporate. With insufficient liquid, only a small amount boils in the coil and most of what leaves the evaporator is vapor at a temperature higher than the coil’s saturated vapor temperature, so the suction gas shows a large rise above the evaporating temperature. This is a clear sign the evaporator is starved for refrigerant.

An excessive charge tends to cause liquid flooding and can lower or normalize superheat, not raise it. An oversized condenser doesn’t directly set evaporator superheat, and a metering device stuck closed would also starve the evaporator, but the symptom described most directly points to insufficient refrigerant reaching the evaporator.