The situation when the upper the chamber is freezing products reach the state of stone, while in the lower compartment the temperature barely reaches positive values, is a classic symptom of a malfunction of the system No Frost or problems with refrigerant circulation. Users often perceive this as a breakdown of the compressor itself, but in most cases the root of evil lies in the cold air distribution system or in a failure of the control electronics.
Understanding the physics of the process helps to avoid panic and unnecessary expenses on calling a technician to diagnose basic things. The refrigeration unit is designed in such a way that the evaporator, where the cooling directly occurs, is most often located in the upper compartment or behind the rear wall of the freezer. From there, cold air should be distributed throughout the entire volume, but if this process is disrupted, a temperature imbalance occurs.
In this article we will analyze in detail the technical reasons for this behavior of the equipment, consider the role of Defrost heating elementsensors and dampers, and also explain why in modern models with electronic control failures occur more often than in older mechanical units.
The principle of operation of the cold distribution system
To understand why the chamber is freezing it is too strong, you need to understand the basic architecture of the refrigerator. In systems No Frost and modern static systems, cooling does not occur directly from the walls, but through forced air circulation. The fan forces air through the evaporator, where it cools, and then distributes it through the channels.
If the upper part (usually the freezer) works aggressively, and the lower (main compartment) is warm, this means that the cold air does not reach the lower levels or its flow is blocked. Freon circulation the circuit may be working properly, the compressor is humming, but the heat exchange between the compartments is disrupted.
⚠️ Attention: Attempts to forcefully open the air dampers or drill additional holes in the partitions are strictly prohibited. This will lead to depressurization of the system and irreversible failure of the equipment.
The key element here is temperature control damper. It is she who doses the amount of cold air coming from the freezer to the refrigerator compartment. If the damper is stuck in the closed position, the cold remains at the top, causing a deep freeze, and there is heat at the bottom.
Faults in the thermostat and temperature sensors
One of the most common reasons why the chamber freezes products is incorrect operation of the thermostat or electronic sensors. In mechanical models, a thermostat is responsible for turning the compressor on and off, which physically opens the circuit when the set temperature is reached.
If the thermostat contacts are “stuck” or the sensitive tube has lost its seal, the compressor continues to operate continuously. As a result, the evaporator in the upper chamber becomes overgrown with ice, the temperature drops to extreme values, and the lower compartment simply does not have time to cool evenly or, conversely, receives excess cold when the door is opened.
In models with a system Full No Frost and electronic control, the role of a mechanical thermostat is performed temperature sensors. There may be several of them: one controls the temperature in the freezer, another in the refrigerator, the third monitors the temperature of the evaporator.
- ❄️ The freezer sensor can give low readings, “telling” the control module that there is still a lot of heat, although the food is already frozen.
- 🌡️ The refrigerator compartment sensor may be misaligned or dirty, which is why it does not record the actual temperature drop.
- 💻 The control module, receiving incorrect data, does not give a command to stop the compressor or close the air damper.
Diagnostics of the sensors requires the use of a multimeter to check their resistance at different temperatures. Often the fault lies not in the sensor itself, but in oxidation of the contacts on the connector or a break in the wiring going to it.
How to check the sensor with a multimeter?
To check, you need to disconnect the refrigerator from the network, find the sensor (usually it is a plastic cylinder with two wires), remove it and place it in a container with water and ice. Then test the contacts with a multimeter in resistance measurement mode. The readings should change depending on the temperature; the exact values are indicated in the technical documentation for the specific refrigerator model.
Problems with the defrost system and ice freezing
If you notice that the chamber freezes is stronger than usual, and ice or a “fur coat” is visible on the back wall inside the freezer compartment, the problem is almost certainly lies in the automatic defrosting system. Ice is an excellent heat insulator, but when there is too much of it, it blocks the air supply channels.
The defrost system consists of three main elements: a heater (Defrost heating element), a defrost sensor (thermostat) and a timer (or relay). Periodically, the compressor turns off and the heating element turns on, which melts the ice on the evaporator. If at least one element of this chain fails, the ice does not melt, but grows.
When the channels are clogged with ice, the fan cannot drive air through the evaporator. A situation arises when at the very top, next to the fan and evaporator, the temperature is critically low (the chamber freezes), and below, where the air simply does not reach due to an ice plug, heat reigns.
☑️ Diagnostics of the defrost system
A common cause of failure is burnout Defrost heating element. It represents a nichrome spiral in a metal tube, and over time it becomes thinner and breaks. The defrost sensor, which should close the heater circuit at a certain temperature, may also become sour.
Failure of the air damper (Damper)
In two-chamber refrigerators, especially with one compressor, cold is generated in the freezer chamber, and is supplied to the refrigeration compartment through a special channel c air damper. This device regulates the flow of cold air, opening and closing at the command of the electronics.
If the damper is stuck in the “Open” position, a constant powerful flow of icy air will flow into the refrigerator compartment. As a result, food in the refrigerator freezes when it should simply be cooling. And vice versa, if it is closed tightly, the refrigerator is warm, and the freezer is working hard.
The dampers are mechanical (controlled by a temperature expander) and electric (controlled by a motor). Electric ones often fail due to failure of drive gears or motor combustion. Mechanical ones can jam due to pieces of ice or debris getting into the mechanism.
| Symptom | Probable cause | Solution |
|---|---|---|
| Everything in the refrigerator is frozen | Dash fully open | Replacing the damper motor or defrosting |
| The refrigerator is warm, there is ice in the freezer | The damper is closed or the channel is clogged | Cleaning the channel, replacing the damper |
| Crackling or buzzing is heard | The motor is trying to move a jammed damper | Lubricating the mechanism or replacing the unit |
| The temperature is fluctuating | Unstable operation of the sensor dampers | Calibrating or replacing the sensor |
To access the damper, partial disassembly of the refrigerator compartment is often required. It is important to act carefully so as not to damage plastic air ducts, which become brittle at low temperatures.
Freon leakage and compressor operation
It may seem paradoxical, but a refrigerant leak (freon) can also lead to uneven cooling, although this is more common like a complete absence of cold. However, in the initial stages of a leak or if there is an “air lock” in the system, the picture may be blurry.
If there is not enough freon, the compressor works continuously, trying to gain temperature. In this case, the first part of the circuit (the evaporator in the freezer) can be very cold, covered with frost, while the refrigerant simply does not reach the end of the circuit (refrigerator compartment) or arrives already warm.
Another option is compressor malfunction. If it has lost performance (valve wear), the pressure in the system is not enough for normal circulation. The cold “slips” only through the freezer compartment, without having time to cool the entire volume.
⚠️ Attention: Diagnosing a freon leak requires professional equipment (leak detector, pressure gauges). Self-search for leaks using the “soaping” method is often ineffective due to the inaccessibility of sealed connections.
It is important to distinguish a leak from a blockage of the capillary tube. When there is a blockage (often due to moisture in the system that has turned into an ice plug), the symptoms are similar: the compressor hums, but there is no cold or it is distributed unevenly.
The influence of the operating mode and loading of products
The reason why the chamber freezesis not always due to a breakdown. Sometimes operating conditions are to blame. For example, if you set the “Super Freeze” mode (usually indicated by a snowflake or the letter S), the refrigerator will work non-stop, freezing everything that comes within the range of the cold flow.
A dense load of food also affects circulation. If you pack your shelves to capacity and cover the vents, air won't be able to circulate. As a result, there will be a freezer at the back wall (where the air exits) and heat at the door. Or vice versa, if the flow is directed directly at the food near the wall.
- 🥩 Hot food: placing a hot pan causes a sharp jump in temperature, forcing the compressor to work at maximum, which can lead to local hypothermia of neighboring products.
- 🌬️ Clogged ducts: a chip packet or a bag caught in the air duct can block the air flow, changing the temperature balance.
- 🚪 Loose fit: if the freezer door seal is damaged, warm, moist air constantly enters there, causing increased ice formation and system failure.
Check the temperature settings. For normal storage, it is enough to set +4...+5°C in the refrigerator compartment and -18°C in the freezer. Lower values in the refrigerator compartment are unnecessary and harmful for many products.
Frequently asked questions (FAQ)
Why, after defrosting, the chamber began to get strong again freeze?
If after complete defrosting (24 hours) the problem returns after a few days, then the reason is not the ice plug, but a faulty component: sensor, heating element or damper. The ice jam was only a consequence, not a cause.
Is it possible to operate a refrigerator if the freezer is freezing, but the refrigerator is not?
For a short time - yes, but you can’t work like that for a long time. The compressor operates in increased mode without stopping, which will lead to overheating and burnout of the windings. In addition, the food in the refrigerator compartment may spoil.
How to understand that the defrost heating element has burned out?
It is difficult without disassembling. An indirect sign is a large amount of ice on the back wall of the freezer and a running compressor. The exact answer will only be given by checking the heating element with a multimeter: if the resistance is infinitely high, the heating element has burned out.
Does the voltage level in the network affect the fact that the chamber freezes?
Low voltage can lead to the compressor being unable to start or working inefficiently. However, the specific symptom “the freezer is freezing, the refrigerator is not” more often indicates problems with the distribution of cold, rather than with the power supply.