The situation when a two-chamber refrigerator stops cooling food in the main compartment, but the freezer continues to operate normally, is one of the most common and misleading faults. At first glance, it seems that if the compressor is humming and there is ice below, then the equipment is working properly, but the absence of cold in the upper compartment indicates a violation of the refrigerant circulation or a failure in the temperature control system. The owner often notices the problem too late, when the products have already begun to deteriorate, and drops of moisture appear on the back wall of the chamber or, conversely, complete dryness.
The physics of the cooling process in modern models, be it Indesit, Atlant or Beko, is tied to the uniform distribution of freon throughout the system or the correct operation of fans. If the top part stops freezing, this does not always mean that the compressor itself has broken down. Most often, the problem lies in blockages, gas leaks or failure of the electronics, which simply “do not see” the need to supply cold to the upper compartment. Understanding how your model works is the key to quick diagnosis.
It is important not to panic and not try to immediately disassemble the unit, armed with a set of tools. The first step is to assess the nature of the motor's operation, the presence of frost on the evaporator and the condition of the products. Diagnostics starts with simple steps that allow you to eliminate common operating errors. In this article, we will analyze in detail the mechanical and electrical reasons for the failure of the upper compartment, so that you can make an informed decision about calling a technician or repairing it yourself.
The principle of operation of the two-chamber system No Frost and Direct Cool
To understand why the cold at the top has disappeared, you need to clearly understand how exactly your refrigerator. In models with a system Direct Cool (drip defrost), freon circulates through tubes frozen into the back wall of the main compartment. Here the evaporator is located precisely in the upper chamber, and the freezer is cooled due to natural convection or a separate circuit. If the top does not freeze, but the bottom works, this often indicates that the refrigerant simply does not reach the upper evaporator due to a blockage or leak.
In units with technology No Frost the situation is different. The evaporator in such models is usually hidden in the freezer compartment (or between the chambers), and cold is forced into the upper compartment using a fan through special air ducts. If the fan has stopped or the air duct is clogged with ice, cold air cannot physically enter the main compartment. In this case, the compressor can work without stopping, trying to cool the sensors that are in the freezer, ignoring the heat above.
What is the key difference between the systems?
In No Frost systems there is one evaporator (usually in the freezer), and the air is driven by a fan. In drip systems (Direct Cool), the evaporator is often located directly in the fridge compartment or a common circuit is used, where the cold is distributed by gravity and convection.
Particular attention should be paid to two-compressor models, where a separate motor-compressor is responsible for each chamber. If you have just such a device, then the problem is local: the upper compressor or its starting relay has failed. In single-compressor models, which make up the majority of the market, failure of the upper compartment when the bottom is working is almost always a problem of circulation or control of cold flows.
Mechanical reasons: freon leak and capillary blockage
The most common technical reason that the refrigerator has stopped freezing at the top is refrigerant leak. Freon is the working fluid of the system, and if its quantity in the circuit decreases due to microcracks in the tubes or corrosion, the pressure is not enough to push the gas to the end of the system. As a result, freon manages to boil and cool only the first section of the circuit (freezer compartment), and reaches the upper compartment in the form of a gas incapable of active heat exchange.
The second common mechanical defect is clogged capillary tube. During operation, oil oxidation products may form in the system or moisture may enter, which turns into an ice plug at the narrowest point. This creates resistance that the compressor cannot overcome. The pressure at the entrance to the capillary increases, and at the exit it drops, the circulation stops. The freezer can remain cold for some time due to inertia or due to residual pressure, but the upper chamber quickly warms up.
⚠️ Attention: Independent soldering of the tubes or an attempt to “blow out” the system without a vacuum pump and professional equipment will lead to complete failure of the refrigerator. Working with refrigerant requires a license and special tools.
It is difficult to diagnose these problems at home, but there are indirect signs. If there is a leak or blockage, the compressor will often run continuously, trying to build up temperature, but will not shut off. The rear grille (condenser) may only be partially hot or remain cold. When you touch the tubes near the compressor, you can notice that one of them is hot, and the return one is at room temperature, although it should be warm.
Problems with the defrosting system in No Frost refrigerators
For owners of equipment with the system No Frost the situation when the freezer is freezing, but the refrigerator is warm, is often associated with a malfunction of the defrosting system. The essence of the problem is that a “coat” of ice is growing on the evaporator, which is located in a hidden block. This ice blocks the fan or blocks the air supply. As a result, cold air cannot circulate through the chambers.
Three main elements are responsible for the defrosting process: Defrost heating element, defrost thermostat (or sensor) and timer (or electronic module). If the heating element burns out, the ice does not melt and gradually freezes more and more until it completely blocks the airflow. If the thermostat is faulty, it may not give the command to turn on the heating, even if there is already ice. Electronics may simply “not see” the need to start a defrost cycle.
Visually it manifests itself like this: inside the refrigerator compartment it is dry, but the food is warm. If you remove the back plastic panel in the freezer (after defrosting the unit), you can see a huge lump of ice on the evaporator. In some cases, ice can block the fan blades, and then you will hear a characteristic crackling or hum that turns into silence.
☑️ Symptoms of defrosting failure
Faulty air damper and fan
In modern two-chamber models, especially with a freshness zone or electronic control, the cold supply is regulated the air damper (damper). This is a special valve that opens and closes at the command of an electronic module, allowing cold air from the freezer to enter the refrigerator compartment. If the damper is stuck in the closed position or the drive motor is burned out, the cold simply does not enter the upper chamber.
Also critically important circulation fan. In Full No Frost systems, it ensures forced movement of air masses. If the fan motor burns out or is jammed with ice, convection stops. Cold air remains in the freezer area, and warm air from the upper chamber does not fall down to cool. You can check the operation of the fan by opening the refrigerator door (in many models, when the door is open, the fan should stop, but if you press the door sensor, it will start).
Often the problem lies in freezing of the channel itself leading from the freezer to the refrigerator. Even a working damper will not be able to open if the passage is clogged with ice chips. This requires completely defrosting the refrigerator within 24 hours. If after defrosting cold appears, but after a couple of days it disappears again, it means that the defrosting system is not working and ice is forming again.
| Component | Function | Symptom of breakdown | Probability |
|---|---|---|---|
| Air damper | Regulates the flow of cold | The damper is closed, it is warm at the top | High |
| Fan | Drives air through the chambers | Noise, lack of circulation | Average |
| Defrosting heating element | Evaporator is heating | Ice build-up, channel blocking | High |
| Defrost sensor | Controls the temperature | No defrost command | Medium |
Failures in the operation of the thermostat and electronic module
If the mechanical part is working properly, the freon is in place, and the ice does not interfere with circulation, you should pay attention to the “brain” and “nerves” of the refrigerator. In older models, the temperature is controlled by thermostat (thermostat). This is a mechanical device with a capillary tube that senses temperature. If the thermostat is “stuck” in the “off” position or its sensitivity is impaired, it does not command the compressor to turn on to cool the upper chamber (in single-circuit systems) or does not adjust the damper correctly.
In refrigerators with electronic control (LG, Samsung, Bosch) the thermostat function perform temperature sensors. There may be several of them: in the refrigerator, in the freezer, on the evaporator. If the sensor in the upper compartment is lying and shows that it is cold there (even though it is actually warm), the control module will not supply cold. A sensor error is often displayed on the display in the form of flashing indicators or a fault code.
The most difficult and expensive breakdown is failure electronic control module. The board may malfunction due to voltage surges, moisture, or old capacitors. In this case, it may send incorrect commands to the compressor, fan or damper. Diagnostics of the module requires a professional tester and knowledge of electronics, since visually burnt elements are not always visible.
Diagnostics and procedure for the owner
What to do if you encounter the problem described? The algorithm of actions depends on your skills and refrigerator model. The first and safest step is always full defrosting. Unplug the refrigerator, remove all food, and leave the doors open for at least 12, preferably 24, hours. This will allow the ice in the hidden channels to melt and drain. After switching on, cold should appear if the problem was in the ice plug.
If defrosting helped only temporarily (for 1-2 weeks), then the defrosting system is faulty and requires replacing the heating element or sensor. If, after defrosting, the upper chamber still does not begin to freeze, and the compressor runs constantly, there is likely a freon leak or a blockage. In this case, independent repair is impossible without a vacuum decanter and a filling station.
Check the tightness of the door. If the seal (elastic band) is worn out or dirty, warm air constantly enters the chamber. The compressor tries to cool it, but due to excess moisture, everything freezes in one place (usually in the corner of the freezer), blocking the channels, or simply cannot cope with the volume of heat in the upper chamber.
⚠️ Attention: Do not try to remove the ice with a knife or sharp objects. Damage to the evaporator will lead to the immediate release of freon and the entry of oil into the system, which will make repairs economically unfeasible.
When you need to call a specialist
There are a number of signs in which attempts at self-repair are useless and even dangerous. If you hear that the compressor turns on, makes a couple of clicks and turns off, or runs around the clock without a break without cooling the top, this is a signal to call a specialist. You also need a technician if you see oily spots under the refrigerator or smell a burning smell.
Professional repairs in case of a leak or blockage include finding the location of the damage, soldering, replacing the filter-drier, evacuation of the system and refilling with new freon. Only a specialist can accurately determine the type of refrigerant (R600a or R134a) and its dosage, since incorrect refilling will lead to rapid failure of the compressor. Replacing a heating element or sensor also requires disassembling the back wall, which is best left to an experienced person so as not to damage fragile plastic and foam.
The cost of repairs often depends on the type of fault. Replacing the start relay or thermostat is inexpensive and quick. Restoring the circuit or replacing the compressor is an expensive procedure that can amount to up to 50-70% of the cost of a new refrigerator. In some cases, especially with older models, it is more economically feasible to purchase new equipment.
Why, after defrosting, did the refrigerator stop freezing again after a week?
This is a classic symptom of a malfunction of the defrost system in No Frost refrigerators. You removed the ice manually, but the automation (heating element, timer or sensor) does not work. Ice builds up again on the evaporator, blocking the air supply channels. Diagnosis and replacement of the burnt-out element of the defrost system is required.
Is it possible to operate the refrigerator if the upper chamber does not freeze?
For a short time - yes, if the freezer is working. However, the compressor will work hard, trying to reach a non-existent temperature, which will lead to overheating and combustion. In addition, food in the upper compartment will quickly spoil. Long-term operation in this mode is not recommended.
How to check if the fan is working in a No Frost refrigerator?
Open the refrigerator door. In many models, the fan stops when the door is open. Find the door sensor button (usually on the end of the frame) and press it with your finger or cover it with tape. If the fan is working properly, a few seconds after closing the door (or pressing the button) you should hear it hum and feel the flow of air.
What does it mean if the back wall of the refrigerator is only half hot?
The condenser (grid at the back) should be warm evenly. If it is only hot at the beginning (near the compressor) and remains hot quickly, this is a sure sign of a clogged capillary tube or lack of freon. The refrigerant does not circulate in a full circle, giving off heat only in the first section of the circuit.
Could the problem be due to improper installation of the refrigerator?
Yes. If the refrigerator is moved close to the wall, the ventilation of the condenser is disrupted. The compressor overheats and cannot effectively cool the refrigerant. Also, if the floor is uneven and the door is skewed, it may not close tightly, letting in warm air. Check the gap at the back wall (at least 5-7 cm) and the adjustment of the legs.