The situation when freezer compartment continues to properly freeze food, while in the refrigerator compartment it becomes heat is one of the most common and insidious problems. Users often ignore the first signs, believing that the equipment is simply “tired” or overloaded, but in reality this indicates a specific failure in the refrigerant circulation system. Understanding the physics of the process will help you quickly navigate the symptoms and prevent spoilage of a large number of products while you are waiting for the technician.
In modern models, especially those equipped with a system No Frost, cooling of the main compartment occurs due to cold air forced from the freezer. If this airflow is disrupted, the temperature in the upper compartment begins to rise, although the evaporator in the lower compartment may remain icy. It is important not to panic and carry out initial diagnostics in order to understand whether the problem lies in a simple setup or whether serious repair of the compressor-condensing unit is required.
In this article we will analyze in detail the mechanics of the operation of two-chamber refrigerators, consider the most likely failure scenarios and explain why independent attempts to “defrost” or “knock” can be useless in certain cases. We will also touch on the topic of saving energy, since a worn-out compressor with damaged thermal insulation or freon leakage consumes significantly more resources.
The principle of operation of dual-circuit and single-circuit systems
To understand why a temperature imbalance occurs, you need to know the basic operating diagram of your device. Most old and budget models use single-circuit system, where one compressor drives freon in a single circle. The refrigerant first passes through the evaporator of the freezer, where it is greatly cooled, and then enters the refrigerator compartment. That is why in such models the freezer is always colder, and poor circulation often leads to the problem described.
More modern and expensive models can be equipped with double-circuit system or two separate compressors. In this case, each compartment has its own independent cooling circuit. If you have a two-compressor refrigerator and the freezer is working, and the refrigerator compartment is warm, the problem is localized exclusively in the upper compartment circuit, which narrows the range of possible malfunctions. However, in single-circuit systems with a system No Frost the key role is played by a fan that distributes cold air.
⚠️ Attention: An attempt to independently open sealed tubes or change a compressor without a license and special tools is life-threatening and leads to irreversible damage to equipment.
It is critically important to distinguish the type of cooling installed in your unit, since the troubleshooting algorithm depends on this. In systems with drip defrosting (“crying wall”), water condenses on the back wall, while in No Frost moisture is removed outside the chamber, and ice should not form on the food. An error in determining the type of system can lead to incorrect diagnosis.
Refrigerant leak: the most common culprit
The most common reason why the refrigerator does not freeze, while the freezer is still cold, is a partial leak of freon. The refrigerant circulates in a closed circuit under pressure. If a microcrack forms in the system, the gas begins to escape. Since the path of freon starts from the compressor and goes first through the freezer, there may still be enough cold there, but the cooled substance simply does not reach the refrigerator compartment in the required volume.
Leaks often occur at soldering points, in foamed parts of the body, or due to corrosion of the metal evaporator tubes. You may notice that the compressor is running almost non-stop, trying to gain temperature, but is humming quieter than usual or, conversely, making strange sounds. Visually on the rear grille of the condenser (usually behind the refrigerator) you can see that it heats up unevenly or only at the beginning.
Is it possible to fill the refrigerator with freon yourself?
Self-refueling is impossible without specialized equipment (vacuum pump, scales, pressure gauge station) and skills. An attempt to refuel “by eye” will lead to compressor failure.
Diagnostics of a leak requires the use of a leak detector or a nitrogen pressure test method, which is a task for a professional service engineer. If you notice oily spots under the refrigerator or on the floor next to it, this is almost a hundred percent sign of depressurization of the system, since oil circulates along with freon.
The capillary tube is clogged with ice or garbage
The capillary tube is a thin copper pipe that serves as a choke in the system, creating a pressure difference between high and low pressure. If there is moisture in the system (entered during poor-quality repairs or due to a leak), it freezes at the narrowest point of the tube, forming ice plug. This blocks the circulation of freon, and the cold stops flowing into the chamber.
Another option is clogging with compressor wear products (copper shavings, oxides) or process debris. In this case, the cork does not melt when defrosting. A symptom of a blockage is often the behavior of the compressor: it turns on, hums for a while, heats up, and then turns off the thermal protection relay. After cooling, the cycle repeats. This phenomenon is called “operation in a cycle.”
| Symptom | Probable cause | Characteristic symptom |
|---|---|---|
| The compressor hums, but does not start | Seizing or starting relay | Clicks every few minutes |
| The refrigerator is warm, the back is hot | Freon leakage | The compressor works without stopping |
| The freezer is icy, in the refrigerator +10 | Capillary clogged | Cyclic operation with overheating |
| The “fur coat” on the back wall is freezing | Thermostat malfunction | The refrigerator does not turns off |
Removing the blockage requires purging the system with nitrogen under high pressure and replacing the filter drier, which absorbs moisture. A simple defrost can temporarily remove the ice plug, but after a few days or weeks the problem will return, since the moisture will not escape from the system.
Malfunctions of the defrosting system in No Frost
In refrigerators with a system No Frost cold is supplied to the main compartment through special channels using a fan. If the automatic defrosting (defrosting) system fails, the evaporator in the freezer becomes overgrown with ice. Ice blocks the operation of the fan, and cold air physically cannot pass into the refrigerator compartment, remaining locked below.
Three main elements are responsible for the defrosting process: defrost heating element (heating element), defrost sensor (thermostat) and timer (or electronic control module). If the heating element burns out or the sensor fails, the ice does not melt, but accumulates. Visually, this may not be immediately noticeable, since the evaporator is often hidden behind a plastic panel inside the freezer.
☑️ System diagnostics No Frost
To check this version, it is often enough to completely defrost the refrigerator (unplug for 12-24 hours with the doors open). If, after turning on, it starts to freeze normally in both compartments, but after 1-2 weeks the problem repeats, it means that the defrosting system is faulty and requires replacement of components.
⚠️ Attention: Do not use a hairdryer or hot water to speed up the defrosting of ice from the evaporator! A sudden change in temperature can damage aluminum tubes or plastic air ducts.
Problems with the thermostat and sensors
Thermostat (thermostat) is a device that commands the compressor to turn on or off depending on the temperature inside the chamber. If thermostat it is faulty and “lying”, it may not give a command to turn on the compressor, believing that the temperature is normal, although in fact it is warm there. In single-circuit systems, the sensor is usually located in the refrigerator compartment.
In modern models with electronic control, the role of a thermostat is performed temperature sensors, transmitting data to the control module. If such a sensor has “ran away” to the side or its contact has oxidized, the module receives incorrect data. For example, the sensor shows +5°C, although in reality it is +15°C, and the compressor does not start. Diagnostics requires testing the sensors with a multimeter at different temperatures.
Sometimes the problem lies not in the sensor itself, but in its incorrect location. If you have recently cleaned or moved your refrigerator, the mechanical thermostat sensing tube may have become dislodged and is no longer making proper contact with the heat exchanger.
Faulty fan
As mentioned earlier, in the system No Frost the fan is responsible for air circulation. If its motor burns out, jams due to ice, or simply wears out, the air stops circulating. As a result, it can be very cold in the freezer (where the evaporator is located), and warm in the refrigerator compartment.
Signs of a fan malfunction can often be heard: either a complete absence of operating sound (in models where the fan should make noise constantly when the compressor is running), or extraneous crackling and humming. Sometimes the fan impeller becomes covered with ice and simply cannot rotate.
To replace or check the fan in most models, you need to get to the evaporator by removing the back panel in the freezer. This requires care, as you can damage fragile plastic latches or break the tightness of the door seals if dismantled carelessly.
Rare causes and mechanical damage
There are also less obvious reasons. For example, door misalignment or damage to the sealing rubber. If the refrigerator compartment is constantly getting warm air from the room, the system may not be able to cool it down, especially if the door is frequently slammed or left ajar. In this case, the compressor wears out, but the temperature does not drop.
It is also worth mentioning problems with the compressor. Although when it breaks, it usually does not freeze anywhere, in rare cases (for example, when one of the valves loses performance or decreases compression), it can create enough pressure to operate in a small circuit (freezer), but not cope with the full volume. This condition is often called “the compressor does not hold pressure.”
The human factor cannot be discounted: incorrect loading of products. If you block the ventilation holes in the back wall with bags or boxes, air circulation is disrupted locally, creating “heat pockets” where food begins to deteriorate, although the temperature sensor shows normal.
Frequently asked questions (FAQ)
How long does it take to defrost the refrigerator if you suspect an ice block?
To completely eliminate the ice plug in the capillary or on the evaporator No Frost it is recommended to keep the refrigerator turned off with the doors open for at least 12, and preferably 24 hours. A short defrosting of 2-3 hours is often not enough to freeze the inner layers of ice in hard-to-reach places.
Is it possible to operate a refrigerator if it does not freeze in the upper compartment?
Short-term - yes, if the compressor does not overheat. However, prolonged operation in this mode is harmful to the engine, since it can work without stopping. In addition, food in the refrigerator compartment will quickly deteriorate, which can lead to food poisoning.
Why is the back wall of the refrigerator hot, but warm inside?
This is a classic sign of a freon leak or blockage. The condenser (grid at the back) heats up because the compressor drives what is left in the system or tries to push through the plug, but heat exchange in the evaporator does not occur due to the lack of refrigerant circulation.
How to check if the fan is working in the No Frost system?
Open the freezer door. In most models, when the door is opened, the fan should stop (there is a door sensor). Press this sensor with your hand (simulating a closed door) without closing the door itself. If the fan does not start and does not blow cold, it is faulty or frozen.
Is it necessary to call a technician to fill it with freon?
Yes, it is necessary. This requires evacuating the system to remove moisture and air, as well as accurately dosing the refrigerant by weight. Unprofessional refueling will lead to rapid failure of the compressor.