The situation when food in the freezer has turned to stone, and on the top shelf of the main compartment the milk has turned sour or simply become warm, is one of the most common and frustrating problems for household appliance owners technicians. Two-compressor systems less often encounter this, since the cooling circuits there are independent, but in No Frost and static cooling systems with one compressor, a violation of the refrigerant circulation or failures in the electronics lead to just such an imbalance.
Often users notice the malfunction does not occur immediately, but only when ice appears on the back wall, or the food begins to deteriorate. Inverter compressor it may continue to hum, creating the illusion of normal operation, although in fact the cooling cycle is broken. Understanding the physics of the process will help you quickly determine the scale of the disaster and decide whether to call a technician or try to fix the breakdown yourself.
In this article we will analyze in detail the mechanical, electrical and system reasons why the cold stops flowing into the refrigerator compartment, remaining in the freezer. In 80% of cases, the problem lies in a clogged capillary tube or a malfunction of the defrost system, and not in a freon leak. We will look at diagnostic algorithms, check the sensors and figure out when complex intervention in the refrigerant system is required.
The principle of operation and distribution of cold in the No Frost system
To understand why a temperature imbalance occurs, it is necessary to briefly consider how air circulation works in modern models. In systems No Frost the cold is generated in a hidden evaporator located behind the rear panel of the freezer. A special fan drives this cold air through the air ducts into the refrigerator compartment.
If the freezer is working perfectly, this means that the compressor is working, the refrigerant is circulating, and the evaporator is producing cold. The problem is localized either in the air path or in the control of this process. Air duct damper (damper) is a mechanical valve that opens at the command of the electronics, releasing cold into the upper chamber.
In models with a drip system (crying evaporator), the cold is distributed differently: the back wall The refrigerator itself is an evaporator. If it is not cooling and the freezer is working, this indicates that the refrigerant passing through the freezer circuit is not reaching the refrigerator circuit or is not circulating there efficiently enough.
⚠️ Attention: Do not attempt to disassemble the piping and valve system unless you have a refrigerant license and a vacuum pump. Interfering with a sealed circuit without equipment is guaranteed to lead to a complete loss of freon and the need for costly refilling.
Malfunction of the fan is another common cause. If the blades are clogged with ice or the motor burns out, air simply does not enter the upper compartment. In older models LG i Indesit this happens quite often due to freezing of the drainage.
Mechanical reasons: blockages, ice and damper malfunctions
The most commonplace, but often ignored reason is physical blockage of air flow. If you tightly packed the refrigerator with food, especially at the back wall, you could block the holes through which cold air flows from the freezer. Circulation must be free, otherwise the thermostat will not get the correct readings.
A more serious problem is the formation of an ice plug in the channel between the chambers. This often happens when the defrost system is faulty. Ice builds up on the evaporator, then pieces of ice can get into the duct, completely blocking the passage. In this case, the fan is humming, the compressor is working, but there is no cold.
If you have a modern model with electronic control, damper motor (damper motor) is responsible for the distribution of cold. It may become stuck in the closed position or fail electrically. You can check its operation by listening to the characteristic click or sound of the motor when you open the refrigerator door.
- ❄️ Check whether the ventilation holes are blocked by products or packaging.
- 🔨 Inspect the damper for mechanical damage or jamming by ice.
- 🌀 Make sure that the fan in the freezer rotates freely and does not make a grinding noise.
☑️ Diagnostics of air channels
Sometimes the problem lies in the refrigerator door seal itself. If the rubber has dried out or the magnetic tape has weakened, warm air is constantly sucked in. The compressor tries to compensate for the heat, working for wear, but due to the design features of the system, the main cold remains in the lower chamber, and the upper one cannot cool to the required temperature.
Defrost system: heating element, timer and sensors
In No Frost systems, periodic defrosting of the evaporator is critical. A chain of components is responsible for this process: Defrost heating element, a defrost sensor (thermostat) and a timer (or electronic module). If any of these elements fails, the evaporator becomes overgrown with a “coat” of ice.
Ice blocks the operation of the fan and blocks the air supply channels. As a result, the freezer, where the evaporator itself is “clogged” with ice, may even become colder than usual (since the ice accumulates cold), and air stops flowing into the refrigerator altogether. Diagnostics begins with testing the heating element.
Often it is not the heater itself that burns out, but fuse (fusion), which is in the heating element circuit to protect against overheating. If it is open, the heating element will never turn on. It is also important to check the defrost sensor: if it “lies” and shows that there is no ice, the heating command will not be received.
| Component | Function | Fault symptom | Checking method |
|---|---|---|---|
| Defrost heating element | Heating the evaporator to remove ice | Ice build-up on the evaporator | Test with a multimeter (there should be resistance) |
| Defrost sensor | Evaporator temperature control | No heating element turned on | Resistance measurement at different temperatures |
| Timer/Module | Switching cooling/defrosting cycles | Chaotic operation or lack of defrosting | Checking the presence of voltage on the contacts |
| Fuse | Protecting the heating element from overheating | Open circuit, heating element does not heat | Visual inspection and continuity testing |
Symptoms of a defrost system malfunction often develop gradually. First, the refrigerator takes longer to reach its temperature, then the compressor operating intervals increase, and eventually the refrigerator stops cooling at all. It is important not to miss this moment.
How to check the heating element without disassembling the entire refrigerator?
Often, access to the heating element is possible only after complete defrosting and removing the back panel of the freezer. However, if your model has a service hole, you can try to ring the contacts suitable for the heater, after first turning off the power. The resistance of a working heating element with a power of 200-400 W is usually 200-400 Ohms. If the device shows infinity, the heating element has burned out.
Problems with the refrigerant: leaks and blockages of the capillary
If the mechanical parts are working properly, and the fan is spinning, but there is no cold, there is a high probability of problems in the freon circulation circuit. Capillary tube clogged - a classic malfunction. In a narrow place in the tube, oil oxidation products or moisture accumulate, turning into an ice plug (if there is moisture) or a mud mass.
When clogged, the compressor tries to push freon, working with overload. The freezer, which is located closer to the compressor outlet or has a separate circuit, continues to freeze, but the refrigerant simply does not reach the refrigeration chamber in the required volume and with the required pressure. A characteristic sign is a hot condenser (grid at the back) and a very hot compressor.
Freon leak is also possible, especially in models with an evaporator foamed into the housing (often found in Bosch, Siemens old years of manufacture). Metal corrosion under the influence of hidden communications leads to microcracks. Freon leaves, the pressure drops, and the system’s performance is only enough for the freezer.
- 🛢️ The blockage is often accompanied by a change in the sound of the compressor (more dull or intermittent).
- 🌡️ If there is a leak, the condenser (side walls or rear grille) will be barely warm or cold.
- 📉 The pressure in the system drops, which can be seen on the pressure gauge when connected by the master.
Treating the blockage requires purging the system with nitrogen under high pressure and replacing the filter-drier. This is a job for the service center. It is almost impossible to remove a clogged capillary on your own without special equipment.
⚠️ Attention: If you hear hissing or whistling from the inside of the housing (especially in places where there is foaming), this may indicate an active freon leak. Do not use an open flame to search for leaks - freon releases toxic substances when in contact with fire.
Electronics: control module and temperature sensors
A modern refrigerator is a computer that controls physical processes. Responsible for everything electronic control module. If the relays on the board that control the compressor or fan are burned out, or the processor is malfunctioning, the command to cool the upper chamber may not be received.
The key role is played by temperature sensors (NTC thermistors). One is in the refrigerator, another is in the freezer, and the third can control the temperature of the evaporator. If the sensor in the refrigerator compartment “lies” and shows the module that it is -5°C, although in fact it is +10°C, the module will not turn on the cooling, considering the task completed.
Checking sensors is carried out by measuring their resistance at a certain temperature and comparing it with a table of ratings for a specific model. Often it is enough to replace the sensor for the system to work correctly. It is also worth checking the integrity of the wiring going to the sensors - wires in the door hinge often break.
In some cases, the problem lies in the compressor start relay. If it is burnt, the compressor may start, but not develop full power, or work on only one circuit (in dual-circuit systems). Replacing a relay is a simple operation, accessible even to a beginner.
Self-diagnosis algorithm and procedure
Before calling a technician, try to carry out an initial diagnosis. This will help you more accurately describe the problem to a specialist and, perhaps, save on an on-site diagnosis if the problem turns out to be a minor one. Start with a visual inspection and listening.
Check whether the light in the refrigerator compartment lights up when the door is opened. If not, there may be a problem in the door contact group, which can also affect the operation of the fan (in some models the fan stops when opened, but if the contact is stuck, it may not start). Make sure that the temperature is set correctly in the settings.
If you find that the back wall of the refrigerator is dry and warm, and everything in the freezer is frozen, and the fan does not make noise, the problem is clearly in the air supply or its circulation. If the wall is cold, but not freezing, the question is the amount of refrigerant or thermoregulation.
- 🔌 Unplug the refrigerator for a day to completely defrost (if you suspect an ice jam).
- 👂 Listen to the operation of the compressor: a steady hum or intermittent clicks?
- 🌡️ Measure the temperature in both compartments after switching on.
⚠️ Attention: Technical characteristics, sensor locations and operating algorithms may vary depending on the manufacturer and year of manufacture of the model. Always check the official technical documentation (service manual) for your specific model before starting disassembly.
Frequently asked questions (FAQ)
Why does the refrigerator work silently, but does not cool, although the freezer freezes?
Most likely, the No Frost system fan has failed. It could stop due to freezing of the bushing or burning of the winding. In this case, the cold is not pumped into the upper chamber. It is also possible that the air duct damper is stuck in the closed position.
Is it possible to operate a refrigerator if the refrigerator compartment does not work?
For a short time - yes, if you only need a freezer. However, the compressor will work in increased mode, trying to cool the upper compartment, which will lead to its overheating and eventual failure. In addition, food in the refrigerator will spoil. It is better to turn off the device before repair.
How much does it cost to repair if the defrost heating element burns out?
The cost consists of the price of the spare part (heating element, sensor, fuse) and the work of the disassembly/assembly technician. The heating element itself is inexpensive, but the labor intensity of the work is high, since it is necessary to get to the evaporator. On average, defrost system repairs fall into the middle price segment.
How can you tell that freon has leaked and the capillary has not clogged?
If there is a leak, the condenser (the grille at the back or the sides) will be cold or slightly warm only at the outlet of the compressor. When the capillary is clogged, the condenser is usually hot, and the compressor runs very loudly and gets very hot. Only a technician with a pressure gauge can make an accurate diagnosis.
Why did the refrigerator start working after defrosting, and then stop again?
This is a classic sign of a malfunction in the automatic defrosting system. You manually defrosted the ice, and the cold started. But since the heating element or sensor is not working, ice has again accumulated during the operating cycle and blocked the system again. Replacement of defrost circuit elements is required.