Owners of modern refrigeration systems are often faced with a paradoxical situation: equipment declared by the manufacturer as No Frost (without frost), begins to become overgrown with an ice crust. Instead of the expected dryness and no need for defrosting, the user finds blocks of ice on the back wall or at the bottom of the chamber. This phenomenon is not only annoying, but also indicates serious malfunctions in the operation of the unit, which can lead to spoilage of products.
The principle of operation of such models is based on forced circulation of air, which passes through the evaporator hidden behind the panel and, already cooled, enters the chamber. Ideally, moisture should not settle on the walls or products. However, if defrost system fails, moisture freezes in the channels or on the evaporator itself, blocking the normal passage of cold air and creating the appearance of a malfunction.
Ignoring the first signs of icing can lead to failure of expensive components such as a compressor or fan. Ice jam disrupts the thermodynamic cycle, causing equipment to wear out. Understanding why the No Frost refrigerator freezeswill allow you to quickly diagnose the problem and avoid costly major repairs.
⚠️ Attention: Operating a refrigerator with a broken defrost cycle for more than two weeks can lead to acidification of the oil in the compressor due to liquid refrigerant.
Violation of the tightness of the door seal
One of the most common reasons for the appearance of ice is a banal loss of tightness. The rubber seal located around the perimeter of the door wears out, becomes deformed or becomes dirty over time. Through the resulting cracks, warm air from the room, containing a large amount of moisture, penetrates into the chamber. This moisture instantly condenses on the cold walls and freezes.
In systems No Frost humidity is the main enemy. Even a slight leak causes the sensors to detect an increase in temperature and force the compressor to work in increased mode. As a result, a “fur coat” forms on the back wall, and huge icicles can grow in the freezer. Often the problem lies not in the rubber itself, but in foreign objects stuck between the shelf and the seal.
Checking the tightness is a simple procedure that you can perform yourself. Use a sheet of paper: clamp it with the door around the perimeter and try to pull it out. If the paper comes out easily and without resistance, it means that the seal does not fit in this place. It is also worth inspecting the surface for cracks or creases.
To restore the tightness, sometimes it is enough to simply wash and degrease the seal with a soap solution. If the rubber has lost its elasticity, the contour will need to be replaced. In some cases, warming up the deformed areas with a hairdryer helps, but this is a temporary measure.
Failure in the automatic defrosting system
The heart of the No Frost system is the defrost control unit, which consists of several key elements: a heater (heater), a defrost sensor (thermostat) and a timer (or electronic module). If the refrigerator begins to freeze, in 80% of cases the problem lies in this unit. Defrost heating element responsible for melting the ice that forms on the hidden evaporator during compressor operation.
If the heating element burns out, the ice stops melting and gradually clogs the drainage channels and the space around the fan. Water stops flowing into the pan and freezes inside the housing. The defrost sensor, in turn, monitors the evaporator temperature. If it is “stuck” in the “on” position, the heating element may not start at all or may not work correctly.
How to check the defrosting heating element with a multimeter?
To check, you need to get to the evaporator, remove the heating element and ring its contacts. The resistance of a working heating element is usually from 200 to 400 Ohms. If the device shows an open circuit (infinity) or a short circuit (zero), the element must be replaced.
Diagnostics of the defrost system requires disassembling the internal panel of the freezer. Before starting work, be sure to unplug the refrigerator. Visually inspect the heating element for swelling or ruptures in the coil. Often, the failure of one element entails the failure of others, so it is better to change them comprehensively.
☑️ Diagnostics of the defrost system
Faulty temperature sensor and thermostat
Electronics of modern The refrigerator relies on sensor readings. If temperature sensor transmits incorrect data to the control module, the operation algorithm is disrupted. For example, the sensor may “think” that the chamber is too warm and not give a command to turn on the defrost mode, although in fact the evaporator is already covered with ice.
Older models use a mechanical thermostat. Its capillary tube is attached to the evaporator. If the contact is broken or the tube is displaced, the thermostat does not sense the actual temperature. As a result, the cooling cycle is delayed, and the defrost pause does not occur at the right time. Ice accumulates faster than it can melt.
Replacing sensors is a simple procedure, but requires precision. It is important to install the new element in the same location and ensure good thermal contact. Using sensors with unsuitable characteristics (different resistance at a certain temperature) will lead to incorrect operation of the entire system.
⚠️ Attention: The characteristics of temperature sensors vary between different manufacturers. When purchasing a spare part, be guided not only by the model of the refrigerator, but also by the marking of the sensor itself or its resistance at room temperature.
Clogged drainage system
Even a properly working defrost system produces water. Melt water should flow freely through the drainage channel into a special tray located above the compressor, where it evaporates. If drainage hole clogs with crumbs, mold or pieces of ice, the water has nowhere to go.
Water begins to accumulate at the bottom of the freezer and freeze, forming an ice “cushion”. Over time, this ice rises higher, cutting off cold air and damaging food boxes. In the refrigerator compartment, water can leak out, forming puddles on the floor.
To clean the channel, you can use a medical bulb with warm water or a special brush. It is not recommended to use sharp metal objects, as there is a high risk of damaging the plastic walls of the channel or piercing the evaporator, which will lead to freon leakage.
Technical malfunctions: heating element, fan, damper
In addition to the main elements of the defrost system, other technical components also affect the formation of ice. Fan, which moves air around the chamber and can cause ice to form. If ice freezes on the blades, the fan will jam, circulation will stop, and the cold will stop flowing into the chamber, although the compressor will work.
The air flow control damper (damper) can also get stuck in the closed position due to ice. This will lead to local hypothermia in one compartment and the formation of condensation in another. In addition, a faulty damper can let in too much cold air, causing intense freezing of moisture from food.
Below is a table of the main symptoms and probable causes:
| Symptom | Probable cause | Necessary actions |
|---|---|---|
| Ice only on the rear wall | Defective defrost heating element | Replacing the heater |
| Ice at the bottom of the freezer and water in the refrigerator | Clogged drainage channel | Cleaning channel |