Which condition can lead to excessive superheat in a refrigeration system?

Excessive superheat in a refrigeration system can occur due to a blockage in the system. When a blockage is present, refrigerant flow is impeded, which may prevent adequate cooling of the refrigerant in the evaporator coil. As a result, the refrigerant does not absorb enough heat, leading to an increase in the temperature of the vaporized refrigerant at the evaporator outlet, which is measured as superheat.

In a properly functioning system, refrigerant should flow unobstructed, allowing it to change from liquid to vapor while absorbing heat. However, if there is a blockage — whether from debris, ice, or another obstruction — it restricts the amount of refrigerant that can enter the evaporator, thereby increasing the superheat. This situation can also contribute to inefficiencies and potentially cause other issues within the refrigeration cycle.

Other conditions, such as a low refrigerant charge or a stuck expansion valve, can also influence superheat levels, but they lead to different symptoms in the system. A condenser fan failure typically causes increased pressure in the condenser and does not directly contribute to high superheat but can affect system performance overall.