The situation when refrigerator suddenly stops coping with its responsibilities always takes you by surprise. You open the door, expecting the usual cold, but instead you feel room temperature, and the food in the upper section begins to quickly spoil. This is a classic symptom that indicates poor refrigerant circulation or a malfunction in the temperature control system. In most modern models, especially those equipped with a system No Frost, cold air is generated in one compartment and distributed to others, so a breakdown in one unit can “immobilize” the entire upper chamber.
You cannot ignore this signal, since the problem may be a simple overload products, as well as a serious freon leak or compressor failure. Understanding how your equipment works is the key to quick diagnosis. If you notice that freezer it is working normally, but it is warm in the refrigerator compartment, or vice versa - the system has stopped cooling everywhere, the algorithm of actions will be different. It is important not to panic and consistently check the main components before calling a technician.
In this article we will analyze in detail the mechanics of the process, possible causes of malfunctions and ways to eliminate them. You will learn how to distinguish a software failure from a physical failure, and what actions you can perform yourself without special equipment. Remember that timely identification of a problem often saves equipment from expensive overhauls.
The principle of operation of the cooling system and cold distribution
To understand why refrigerator stopped cooling the upper part, you need to know how exactly the cold gets there. In classic two-compartment models with a single compressor, the refrigerant passes through an evaporator, usually located in the freezer or behind the rear wall of the refrigerator compartment. The fan forces cooled air through special channels into the upper chamber. If this process is disrupted, the top part remains warm.
In models with the system No Frost the evaporator and its defrosting system are a critical element. The ice formed on the evaporator is periodically melted by a heating element (heating element). If the heating element burns out or the defrost sensor “lies,” the evaporator becomes covered with an ice coat that blocks the ventilation holes. As a result, the air simply cannot circulate, and the temperature at the top rises.
There is also a technology Full No Frostwhere separate evaporators can be installed in each compartment, but more often one common circuit is used. Loss of the door seal or damage to the seal leads to a constant influx of warm, moist air, which causes the system to wear out and eventually causes freezing of the air supply channels.
⚠️ Attention: If you hear that the fan is humming, but no air is blowing from the holes, the air channel may be completely clogged with ice. Do not try to break through the ice with a knife or sharp objects - this is guaranteed to lead to depressurization of the system and leakage of freon.
Differences in design also dictate different troubleshooting methods. In “crying” refrigerators (drip system), the problem often lies in a clogged capillary tube or leak, while in No Frost more often the electronics or defrost system are to blame.
Problems with the thermostat and temperature sensors
One of the most common reasons for which refrigerator does not freeze at the top is due to incorrect operation of the thermostat or air sensor. The thermostat is the brain that tells the compressor to turn on when the temperature rises above a set point. If its contacts are stuck or it fails, the compressor may simply not start, or, conversely, work without stopping, freezing the bottom, but not having time to cool the top due to a violation of the cycle.
In modern models with electronic control, the role of a mechanical thermostat is performed temperature sensors (thermistors). They are located at different points: on the evaporator, in the air duct, in the refrigerator compartment itself. If the sensor that controls the temperature in the upper chamber transmits incorrect data to the control board, the system “thinks” that there is cold there and does not turn on the cooling.
- ❄️ Failure symptoms: the compressor works rarely or does not turn on at all, although it is warm in the chamber.
- 🔌 Diagnostics: testing the thermostat with a multimeter at different temperatures.
- 📉 Signs of sensor failure: an error appears on the display (for example, code F or a flashing indicator), the temperature does not correspond to the readings.
Replacement thermostat or sensor - a procedure that can be done with your own hands if you have basic electrical skills. However, it is important to choose an analogue with exactly the same parameters, otherwise the operating modes refrigerator will be disrupted.
⚠️ Attention: Before replacing any electrical components, be sure to disconnect the device from the power supply. Working with live wiring is dangerous and can lead to burnout of the control board.
Faults of the compressor and start relay
The heart of any refrigerator is compressor. It is he who pumps the refrigerant through the system, creating the necessary pressure drop for cooling. If the compressor hums but does not start, or starts for a couple of seconds and turns off with a click, the problem most likely lies in the starting relay or the motor itself.
The starting relay is responsible for supplying a starting pulse to the motor windings. Over time, the contacts in the relay oxidize or burn out, and it ceases to perform its function. In this case, the compressor tries to start, hums, overheats and is switched off by the protection. As a result, no cold is produced at all, and the temperature in all chambers (both above and below) becomes room temperature.
A more serious situation is an interturn short circuit in the compressor windings or its mechanical wear. If engine it burns out, its replacement requires not only financial costs, but also professional vacuumization of the system and refilling with freon, which cannot be done at home.
You can check the operation of the compressor visually and by ear. If it's hot but doesn't get cold, that's a bad sign. If it is cold and silent, check for voltage at the terminals.
Clogged capillary tube and refrigerant leak
If the compressor runs continuously, hums, trying to gain temperature, but refrigerator stopped cooling the upper part (or freezes only near the evaporator), there is a high probability of blockage capillary tube or freon leak. The capillary tube is the thinnest channel through which the refrigerant enters the evaporator. A blockage can occur due to moisture in the system, oil oxidation, or debris from poor-quality repairs.
When freon leaks, the pressure in the system drops. There is simply not enough refrigerant to go through the full cycle and cool the entire volume of the chambers. Often in such cases, the upper part stops freezing first, since the refrigerant reaches it last, and then the cold disappears in the freezer.
The leak can be diagnosed by indirect signs: swelling of the walls of the housing, the appearance of rust on the tubes at the back, the absence of a characteristic hiss when turned on. It is difficult to fix a leak and refill the system on your own, since it requires special equipment to find the location of the damage and evacuate it.
Is it possible to refill the refrigerator yourself?
Independent refilling is possible only if you have professional equipment (vacuum pump, pressure gauge station, scales) and skills in soldering copper pipes. Without evacuation, residual moisture in the system in a short time will lead to blockage of the capillary with ice and failure of the compressor.
The table below shows the main signs that help to distinguish a blockage from a leak:
| Symptom | Clogged capillary tube | Freon leak |
|---|---|---|
| Compressor operation | Works constantly, gets very hot | Works constantly or turns on rarely |
| Condenser temperature (rear grille) | Hot only at the beginning of the circuit, then cold | Barely warm or cold along the entire length |
| Evaporator | May be partially covered with frost | Clean, without frost, or frost only at the entrance |
| Sound when work | Gurgling sounds in the pipes | There are no refrigerant noises or they are quiet |
Failures in the defrost system (for No Frost)
For owners of equipment with the system No Frost this is one from the most critical sections. If refrigerator it stops cooling at the top, but freezes normally at the bottom (or the freezer is working, but the refrigerator compartment is not), in 80% of cases the evaporator defrosting system is to blame.
The essence of the problem is that moisture from the food settles on the cold evaporator and turns into ice. It should turn on periodically (usually every 8-12 hours), melting this ice. The water flows into the drain. If the heating element is burned out, or the thermal fuse is blown, or the defrost sensor does not give a command to turn on the heating, ice builds up in layers. Sooner or later, it freezes so much that it blocks the channels through which the fan should blow cold air into the upper chamber. Defrost heating element, melting this ice. The water flows into the drain. If the heating element is burned out, or the thermal fuse is blown, or the defrost sensor does not give a command to turn on the heating, ice builds up in layers. Sooner or later it freezes so much that it blocks the channels through which the fan should blow cold air into the upper chamber.
Visually it manifests itself like this: the back wall in the freezer may be covered with a thick layer of ice or snow, the fan hums, but no air flows. In some cases, ice even blocks the fan blades, and it starts to crack or stops.
- 🔥 Heating element: checked for resistance (should be within normal limits, usually 200-400 Ohms).
- 🛡️ Thermal fuse: should “ring” (show a circuit), if it burns out, the circuit broken.
- 🌡️ Defrost sensor: changes resistance depending on temperature, requires checking with a multimeter.
The solution to the problem is defrosting the refrigerator within 24 hours (complete!) and replacing the faulty element defrosting systems.
The influence of seals and proper loading
The reason does not always lie in complex electronics or mechanics. Sometimes refrigerator does not hold the temperature due to a banal seal failure. If the rubber door seal is old, cracked or dirty, warm air constantly enters the chamber. The cooling system cannot cope with its cooling, and in the upper part, where the temperature is already higher, the food spoils.
Proper loading is also important. If you place a hot pot or pack the shelves too tightly with food, blocking the air circulation holes, the cold simply cannot be distributed evenly. In systems No Frost air circulation is the basis of operation, and any obstructions in the path of air flow lead to local overheating.
Check that the door closes tightly. A sheet of paper clamped around the perimeter should not be easily removed. If the seal has come off, you can try to restore it using a hairdryer (heat and straighten it) or replace it with a new one.
Diagnostics and checklist of actions
Before calling a technician, it is worth carrying out an initial diagnosis. This will help you more accurately describe the problem to a specialist, or perhaps solve it yourself. Start with the simplest thing: checking the voltage in the network and the integrity of the power cord.
Then listen to the operation of the unit. The compressor should operate in cycles: turn on, hum, turn off. If it is silent or buzzes non-stop, these are clear signs of a malfunction. Check the temperature of different parts of the case: the side walls should be warm (this is normal), and the back grill should be hot.
Use the following checklist to quickly check the condition of the device:
☑️ Primary diagnostics of the refrigerator
If the problem does not disappear after defrosting for 24 hours, most likely, replacement of parts or professional repairs are required.
When you need to call a technician
There are a number of situations where attempts at self-repair can lead to permanent breakdown of the equipment. If you find mechanical damage to the tubes, traces of oil on the floor, or a burning smell, immediately stop using it and contact service.
Professional help is also needed if, after replacing the thermostat or heating element, the refrigerator does not start working correctly. Perhaps the problem lies in the control module, which requires flashing or complex diagnostics with an oscilloscope.
Do not forget that modern refrigerators are complex electronic-mechanical devices. Interfering with the refrigerant circulation system without a license and equipment is prohibited and dangerous.
Why does the refrigerator freeze but does not turn off?
Most often this indicates a freon leak (the system cannot gain temperature) or that the thermostat/sensor does not sense the real temperature and does not give a command to stop the compressor. It is also possible that air can leak through a leaky seal.
Is it possible to use a refrigerator if it does not freeze at the top?
For a short time - yes, but the food in the upper chamber will quickly spoil. Long-term operation in this mode is dangerous for the compressor, which can burn out from overload, trying to compensate for the lack of cold.
How long does it take to defrost the refrigerator if there is a problem with defrosting?
Minimum 24 hours. The ice in the evaporator channels melts slowly. If you turn on the refrigerator earlier, the water will freeze again, and the problem will return in a couple of days.
What to do if a strange smell appears in the refrigerator?
If the smell is chemical or similar to freon, there may be a leak, you need a technician. If there is a smell of mold or rot, thoroughly wash the chamber with a soda solution and check the drainage hole on the back wall, it could be clogged.