What is a common cause of overdefrost in a defrost cycle other than a refrigerant issue?

What is a common cause of overdefrost in a defrost cycle other than a refrigerant issue?

• A. Defrost termination failure
• B. Low ambient temperature
• C. Overcharging the system
• D. Underheating the case

Answer: (A)

In a defrost cycle, the evaporator heater melts frost for a set amount of time, and the cycle ends when a defrost termination device signals completion. If that termination mechanism fails to trip, the heater keeps running beyond the intended duration, causing more ice to melt than planned and resulting in overdefrost. This is a common issue that isn’t related to how much refrigerant is in the system, but to the controls that stop the defrost cycle. Low ambient temperature can affect overall refrigeration performance, but it doesn’t inherently cause the defrost run to extend beyond its intended time. Overcharging the system is a refrigerant problem and not a control-duration problem, while underheating the case points to inadequate cooling rather than an extended defrost period.

In a defrost cycle, the evaporator heater melts frost for a set amount of time, and the cycle ends when a defrost termination device signals completion. If that termination mechanism fails to trip, the heater keeps running beyond the intended duration, causing more ice to melt than planned and resulting in overdefrost. This is a common issue that isn’t related to how much refrigerant is in the system, but to the controls that stop the defrost cycle.

Low ambient temperature can affect overall refrigeration performance, but it doesn’t inherently cause the defrost run to extend beyond its intended time. Overcharging the system is a refrigerant problem and not a control-duration problem, while underheating the case points to inadequate cooling rather than an extended defrost period.