There is usually not just one heating tube in the refrigerator, but they are distributed in different positions according to their functions.
1. Frost-removal heating tube – The most important heating tube
Position: Close to the bottom of the evaporator or interspersed among the evaporator fins.
Function: Specifically designed to melt the frost on the evaporator.
Working process (automatic defrosting cycle):
1. Frost formation: During normal refrigeration, the surface of the evaporator accumulates frost.
2. Start: After the compressor has run for a certain period of time (typically 8-12 hours), the defrosting timer or the main board controls to cut off the power supply to the compressor and stop the refrigeration.
3. Heating: At the same time, the defrosting heating tubes are powered on. The heating tubes heat up, like “electric heating wires”, directly heating the evaporator to melt the frost layer.
4. Drainage: The melted frost water flows through the drainage holes to the water collection tray at the bottom of the refrigerator.
5. Stop: When the heating reaches the preset time or the temperature of the evaporator rises to the set value (perceived by the defrost temperature controller/dual metal switch), the heating stops.
6. Recovery: The compressor restarts, restoring refrigeration. The water in the water collection tray will naturally evaporate due to the heat generated by the compressor operation.
Features: High power, usually ranging from several tens of watts to over one hundred watts, but the working time is very short (total possibly less than one hour per day).
2. Door frame heating tube (door edge frame)
Location: Embedded around the edges of the refrigerator door frame (you can feel the plastic part inside when touching the door edge with your hand).
Function: Slightly heats the door frame to keep its surface temperature always above the dew point temperature, thus preventing the door frame from “sweating” and condensing.
Feature: The power is very low (usually from a few watts to several tens of watts), it is for long-term or intermittent use, the surface temperature is only slightly warm and will not be hot to the touch.
3. Water collection tray heating tube
Location: Below or inside the water collection tray at the bottom of the refrigerator.
Function: When the ambient temperature is low (such as in winter), the compressor operates for a short period of time and the generated heat is insufficient to completely evaporate the defrost water in the water collection tray. The heating tube of the water collection tray can slightly heat up to accelerate the evaporation of the water and prevent the accumulation of water from breeding bacteria.
Feature: Low power, usually working in conjunction with the ambient temperature.
4. Air duct heating tube / Temperature zone compensation heating tube
Location: Located within the air supply ducts of the refrigeration room or the temperature control room. Function:
In compartments that require higher temperatures (such as the refrigeration compartment), the cold air from the evaporator is slightly heated to reach the set supply temperature, achieving precise temperature control.
Prevent the air duct outlet from freezing due to excessive coldness.
Features: Low power consumption, precisely controlled by the computer board.
Post time: Oct-10-2025