If the cooling plate (evaporator) in the lower compartment of your fridge is covered with ice on one side only, and the cooling efficiency is lower than usual, the probable cause is a malfunctioning defrost system. This issue is commonly found in refrigerators with a separate freezer compartment and a refrigerator section.
Here's how the defrost system works and the probable causes of the problem:
Defrost System: The defrost system in a refrigerator is responsible for preventing excessive ice buildup on the cooling coils (evaporator) in the refrigerator and freezer compartments. It usually consists of a defrost heater, a defrost thermostat, and a defrost timer or control board.
Defrost Heater: The defrost heater is used to melt the frost and ice that accumulates on the cooling coils during normal cooling cycles. It turns on periodically to heat up the coils and thaw any ice formation.
Defrost Thermostat: The defrost thermostat monitors the temperature of the cooling coils. If the coils become too cold during the cooling process, the thermostat signals the defrost heater to turn on and melt the ice.
Defrost Timer or Control Board: The defrost timer or control board controls the timing of the defrost cycle. It determines when the defrost heater should activate to melt the ice buildup.
Probable Cause:
The most likely cause of ice buildup on only one side of the cooling plate in the refrigerator compartment is a malfunction in one of the components of the defrost system. The probable causes are:
Defrost Heater Failure: If the defrost heater is not working correctly, it won't generate enough heat to thaw the ice on the cooling coils fully. As a result, ice will accumulate on one side while the other side remains relatively ice-free.
Defrost Thermostat Failure: If the defrost thermostat is faulty, it may not signal the defrost heater to turn on, leading to uneven ice buildup on the cooling coils.
Defrost Timer or Control Board Issue: A malfunctioning defrost timer or control board can disrupt the defrost cycle, causing ice to accumulate on one side of the cooling plate.
To resolve this issue, you will likely need to have the defrost system components checked and replaced by a qualified appliance repair technician. They can diagnose the specific problem and replace any faulty parts to restore proper defrosting functionality to your refrigerator.