The situation when the system refrigerator No Frost stops cooling the upper chamber takes any owner of household appliances by surprise. Products begin to deteriorate, and condensation appears on the shelves or, conversely, the cold disappears where it should be. This is a common problem that often indicates a failure in the air circulation system or a malfunction of defrosting components.
Unlike classic models with a weeping evaporator, in No Frost units the cold is generated in one place and distributed by a fan. If this process is disrupted, the upper compartment is the first to suffer. Understanding the principle of operation will help you quickly determine whether the breakdown can be fixed yourself or whether you need to call a technician.
Do not panic ahead of time. Often the cause is simple clogging of the channels or freezing of the damper, which can be solved by defrosting. However, in some cases we are talking about more serious technical problems, such as failure compressor or refrigerant leakage. Let's look at the main scenarios.
The principle of operation of the No Frost system and the features of cold distribution
To understand why the upper chamber does not work, you need to know how yours works. In know frost systems, the evaporator is hidden in the rear wall of the freezer (or in a separate block). The fan drives cold air through special channels into the refrigerator compartment. There it passes through refrigerator. In know frost systems, the evaporator is hidden in the rear wall of the freezer (or in a separate block). The fan drives cold air through special channels into the refrigerator compartment. There he goes through air intake holes and cools the food.
Air circulation is the key point. If the fan stops or the ducts are blocked by ice, the cold simply does not reach the upper shelves. At the same time, the temperature in the freezer may remain normal, which confuses the user. Imbalance between the freezer and refrigerator compartments is the first sign of problems with the defrosting system.
It is important to note that in different brand models Liebherr, Bosch or Indesit channel design may vary. Somewhere a single damper is used, somewhere a complex system of dampers is used. Understanding this mechanics allows you to correctly diagnose the problem.
Full defrosting as a method of primary diagnosis
The simplest and often effective way to return cold to the upper chamber is complete defrosting. If a “snow coat” has formed on the evaporator in the system, it blocks the operation of the fan and blocks the channels. Ice interferes with normal circulation, and cold air physically cannot enter the upper compartment.
To carry out the procedure, you must turn off the device from the network, empty the chambers of food and leave the doors open for at least 12, and preferably 24 hours. Just waiting a couple of hours is not enough - ice in hard-to-reach places may not have time to melt. After this, turn on the refrigerator and check the operation. defrosting systems may not have time to melt. After that, turn on the refrigerator and check the operation.
⚠️ Attention: Do not use a hairdryer or hot water to speed up defrosting! A sudden temperature change can damage the plastic housing of the evaporator or lead to cracks in the tubes, which will cause freon leakage.
If after defrosting the refrigerator worked normally, but after 1-2 weeks the problem recurred, it means that one of the elements of the defrosting system is faulty. This could be a heating element, defrost sensor or timer. In this case, the ice will build up again, blocking the channels.
☑️ Correct defrosting algorithm
Malfunctions of the defrosting system: heating element, sensors and timer
If defrosting helped temporarily, it means that the automation is not doing its job. In normal mode defrost cycle it starts several times a day. If the heating element does not turn on, ice builds up on the evaporator, the fan stops spinning or begins to hum, touching ice, and stops pumping air.
The defrost sensor (defroster) often fails. It must record the temperature of the evaporator and give a command to turn on the heater. If the sensor is lying, heating will not start. Also, a problem may be a fuse that blows when the heating element overheats, breaking the circuit.
Diagnostics of these elements requires a multimeter. It is necessary to “ring” the heating element for an open circuit and check the sensors for resistance. In models with electronic control, an error can be shown by a code on the display, but in mechanical models you will have to check all components manually.
| Component | Function | Failure symptom | Check method |
|---|---|---|---|
| Heating element defrost | Evaporator heating | Ice build-up, no cold | Resistance test |
| Defrost sensor | Temperature control | The heating element is not turned on | Resistance measurement |
| Timer/Board | Cycle management | Chaotic operation or stopper | Checking the voltage at output |
| Fuse | Overheat protection | Open heating element circuit | Visual inspection and continuity test |
Where is the heating element?
In most models of know frost the heating element is hidden behind a plastic panel in the freezer. To get to it, you need to remove all the shelves, drawers and unscrew the screws securing the back wall. Be careful with plastic latches - they are fragile in the cold.
Problems with the thermostat damper and fan
There is an air damper (damper) between the freezer and refrigerator compartments. It regulates the amount of cold air coming from above. If the damper is stuck in the closed position or its drive is broken, the cold simply will not flow into the upper compartment.
The second important element is evaporator fan. If it stops, circulation is not possible. This can happen due to freezing of the blades or failure of the motor. A characteristic hum or whistle when the compressor is operating often indicates that the fan is trying to spin, but ice is preventing it.
In some models Samsung or LG the damper drive is controlled electronically. If the damper motor burns out, it will remain in the last position. You can check this by getting to the air duct and assessing the mechanical movement of the damper when switching modes.
Freon leak and problems with the compressor
A more serious reason is a refrigerant leak. If there is little freon in the system, it is only enough to cool the beginning of the evaporator (which is located in the freezer), and the cold does not reach the upper chamber. In this case, the compressor can work almost non-stop, trying to gain temperature.
Signs of a leak: a hot back wall (condenser grill) is only partially or completely cold, a swollen inner wall in the freezer (the foam insulator has peeled off), no characteristic gurgling noise at startup. In this case, simple defrosting will not help.
It may also fail itself compressor. If it hums, clicks, but does not start, or works but does not create pressure in the system, the unit needs to be replaced. This is a complex repair that requires evacuation of the system and charging with freon.
⚠️ Attention: Self-filling the refrigerator with freon without a vacuum sealer and scales is prohibited and dangerous. An incorrect amount of refrigerant or the presence of moisture in the system will lead to rapid compressor failure.
Clogged capillary tube and other rare causes
Sometimes the problem lies in a clogged capillary tube through which freon moves. This can happen due to moisture in the system or oil breakdown products. The symptoms are similar to a leak: the refrigerator is humming, but there is no cold in any chamber, or it is weak and only in the freezer.
A malfunction of the control module is less common. The electronics may malfunction, not giving the correct commands to turn on the compressor or fan. In such cases, a reboot helps (disconnect from the network for 15 minutes), but if there is an error in the firmware or a board element is burned out, repairs will be required at the service center.
It is also worth checking the tightness of the sealing rubber bands. If warm air constantly enters the chamber, the system does not have time to cool it, and the sensors may incorrectly control the operation of the unit. This is especially true for older models.
FAQ: Frequently asked questions
Why does ice freeze in a No Frost refrigerator if there is no moisture?
Ice in the know frost system is formed from moisture contained in products and air that enters the chamber when the door is opened. In a working refrigerator, this ice is regularly removed by an automatic defrost system. If ice accumulates on the walls or food, the defrosting system does not work.
Is it possible to operate the refrigerator if the top does not freeze?
Short-term - yes, but the food in the upper chamber will quickly deteriorate. Long-term operation with a faulty defrost system will lead to ice accumulation on the fan, which can cause its breakdown or even jamming of the compressor due to overload. It is better to eliminate the cause.
How much does it cost to repair a know frost system?
The cost depends on the breakdown. Replacing the heating element or sensor is usually inexpensive. If you need to replace the compressor or search for a leak with refilling with freon, the price will be much higher, since special materials and labor-intensive work are needed.
Why did the refrigerator work after defrosting, but a month later it stopped again?
This is a classic sign of a malfunction of one of the elements of the defrosting system. Defrosting eliminated the consequence (ice jam), but not the cause. Most likely, the heating element of the heater has burned out or the defroster sensor has failed. Diagnostics with a multimeter is required.