The situation when Bosch refrigerator stops freezing in the upper compartment, but the lower one continues to work normally, is a classic sign of a refrigerant circulation problem. The owner notices that the food in the freezer begins to thaw, puddles appear or, conversely, a thick “coat” of ice grows, while the main compartment retains heat. This condition requires immediate intervention, since ignoring the problem can lead to spoilage of supplies and failure of the compressor.
Most often, the root of the evil lies in the system No Frost, which is designed to ensure uniform distribution of cold air, but if it malfunctions, it gives just that symptoms. Evaporator may be blocked by ice, or the fan has stopped moving air through the channels. In models with a drip defrosting system, the problem is often associated with a freon leak or a clogged capillary tube. The exact diagnosis depends on the specific series and year of manufacture of the device.
Before calling a technician, it is necessary to carry out an initial diagnosis in order to exclude trivial causes that do not require complex repairs. If the compressor runs continuously, without turning off for hours, and the temperature in the upper chamber does not fall below +10°C, this indicates a serious malfunction of the cooling system. In some cases, it is enough to simply defrost the unit or clean the drainage hole to restore its functionality without financial costs.
Violation of the defrosting mode and an ice coat
The most common reason is that Bosch refrigerator It doesn’t freeze well at the top, there is a failure in the automatic defrosting system. In units with technology No Frost frost settling on the hidden evaporator must periodically melt thanks to the heating element. If this process is disrupted, the air supply channels become overgrown with ice, and the cold simply cannot enter the upper chamber.
Visually this manifests itself in the form of abundant snow build-up inside the freezer or, conversely, a complete absence of frost when the compressor is running. Often the culprit is a burnt out Defrost heating element or failed defrost sensor, which does not give the command to turn on the heating. It is also possible that the timer is stuck or there is a problem with the control module, which “forgets” to start the defrost cycle.
⚠️ Attention: If you notice that the back wall of the freezer is covered with an uneven layer of ice or “swells”, under no circumstances try to knock off the ice with a knife or sharp objects. This is guaranteed to lead to breakdown of the evaporator and leakage of freon.
To confirm this theory, partial disassembly of the rear panel of the freezer is often required. Inside, you may find that it fan is spinning, but air is not passing through the radiator due to an ice plug. In such cases, the technician will have to warm up the evaporator, check the heater resistance and the integrity of the defrost fuse.
Hidden signs of defrost system malfunction
The fan may hum or crackle, trying to break through the ice plug. Sometimes you can hear the characteristic sound of cracking ice when you try to start the compressor. Also, water may appear on the floor near the refrigerator if the drainage is full due to freezing.
Refrigerant leak and capillary system blockage
If defrosting the unit for a day did not bring results, and the upper chamber is still warm, there is a high probability of a more serious technical problem. Freon leak is the second most common cause of loss cold. The refrigerant can escape through microcracks in sealed joints, through corrosion of pipelines (especially at the sealing site of the filter drier) or through the evaporator if it was damaged earlier.
If there is a leak, the compressor works almost non-stop, trying to reach the set temperature, but cannot do this. Unlike the system No Frost, where air circulates forcibly, in models with a drip system, cold air simply ceases to be produced in sufficient volume. First, the cold disappears in the upper compartment, since it reaches there according to the residual principle, and then the bottom stops freezing.
Another option is clogged capillary tube. Oil circulates in the system, which can become coked over time, or moisture gets into the tube, forming an ice plug. This creates an obstacle to the movement of freon. The pressure in the system drops and the refrigerant does not reach the evaporator at the top of the chamber.
Diagnosis of these problems requires special equipment: a pressure gauge station for checking pressure and a leak detector. Finding a leak or breaking through a blockage on your own is almost impossible without evacuation of the system and filling with new gas.
Faults of sensors and control module
Modern refrigerators Bosch are stuffed with electronics that control every step of the unit’s operation. If temperature sensor the upper chamber fails or begins to “lie,” it can send a signal to the control module that there is cold there, although in fact the temperature is higher than normal. In response to this, the compressor turns off, preventing cold from accumulating.
A similar situation occurs with the evaporator sensor. If it shows incorrect data, the system may end the refrigeration cycle prematurely or, conversely, not start defrosting. In more complex cases, the problem lies in the control module (board) itself. Power surges in the network often lead to burnout of tracks or relays that control the compressor and fans.
Symptoms of electronic failure are often accompanied by blinking indicators on the control panel or the appearance of error codes on the display (if provided by the model). For example, a flashing temperature light may indicate a specific fault zone. Without connecting a diagnostic tester, it is difficult to accurately determine the burnt element.
Problems with the fan and damper
In two-chamber models with a system No Frost cold is forced into the upper compartment. The fanlocated in the freezer is responsible for this process. If it stops due to freezing of the bushing, entry of a foreign object or combustion of the motor winding, air circulation stops. As a result, it can be cold in the freezer (due to the proximity to the evaporator), and warm in the upper compartment.
Another important element is the air damper (damper). This is a mechanical or electrical damper that regulates the flow of cold air from the freezer to the refrigerator compartment. If the damper is stuck in the closed position, cold air physically cannot get up. This often happens due to ice on the damper mechanism or a breakdown of its drive.
You can check the operation of the fan by opening the freezer door and pressing the door open sensor button (simulating a closed door). If the fan does not hum, then the problem is in it or in the voltage supply to it. Sometimes it is enough to simply defrost the unit for 10-12 hours so that the ice in the fan hub melts and it starts working again.
| Symptom | Probable cause | Necessary actions |
|---|---|---|
| Fan hums, but does not spin | Freezing of the bushing or breakage of the blades | Defrosting or replacing the fan |
| The fan is silent | The winding is burned out or there is no power | Checking with a multimeter, replacement |
| Noise when the damper is operating | A foreign object or ice has entered | Cleaning the channel, checking the mechanism |
| There is cold only at the back wall | Failure of the damper or channels | Adjusting or replacing the damper |
Mechanical damage and wear of seals
Sometimes the problem lies not in the insides, but in the tightness of the circuit. If sealing rubber band the upper chamber door is worn, dirty or deformed, warm air from the room constantly enters the chamber. The compressor cannot cope with the compensation of heat inflow, and the temperature inside rises.
You can check the tightness with a simple test with a sheet of paper: clamp the sheet with the door around the perimeter. If it is pulled out without effort or falls out easily, the seal does not fit tightly. Also, the cause of leakage may be a misalignment of the door due to loose hinges or overhanging the door in the past.
Mechanical damage also includes dents on the body, which could pinch the freon supply channels (in the foamed part), although this rarely happens. A more common situation is a violation of the thermal insulation of the polyurethane foam layer due to impacts or manufacturing defects, which leads to freezing of the walls and loss of cold.
☑️ Diagnosis of the seal
Operation rules and prevention
In order Bosch refrigerator to serve for a long time and not create problems with cooling the upper chamber, it is important to follow the operating rules. Do not place hot foods in the chamber - this creates excess humidity, which instantly turns into an ice crust on the evaporator, blocking the operation of the system No Frost.
Regularly check the cleanliness of the condenser (the grille at the back), as a layer of dust several millimeters thick significantly impairs heat transfer. The compressor begins to wear out, trying to compensate for poor heat dissipation, which can lead to overheating and stopping.
⚠️ Attention: Do not cover the ventilation holes inside the chambers with food or packaging. Impaired air circulation inside the refrigerator is one of the most common causes of local lack of cold.
It is also not recommended to completely fill the freezer to capacity, leaving a minimum of space for air circulation. Periodic, at least once a year, complete defrosting of the refrigerator (even the system No Frost) helps prevent the formation of hard-to-remove ice plugs in hard-to-reach places.
When you need to call a technician
If simple methods like defrosting, checking the tightness of the door and cleaning the condenser did not help, and the Bosch refrigerator still does not freeze in the upper chamber, professional diagnostics are required. This is especially important if you hear extraneous sounds, see oil near the unit or smell a specific smell.
Independent repair of the cooling system, replacing the compressor, searching for freon leaks or resoldering pipes requires special tools and a license to work with refrigerants. An attempt to do this “on the knee” often ends in the final breakdown of the equipment.
The technician will be able to accurately determine whether the sensor needs to be replaced, refilled with freon, or a complex repair of the control module. In some cases, repairs may not be economically feasible if the cost of the work exceeds 50% of the price of a new device, especially for older models.
Why is the top chamber warm, but the freezer is working?
This is a classic sign of air circulation problems (a problem with the fan or damper) or the initial stages of a freon leak/clog. The cold produced by the compressor is only enough for the closest evaporator in the freezer, and it no longer reaches the top.
How long does it take to defrost a Bosch refrigerator?
For high-quality defrosting and thawing of ice in the hidden channels of the No Frost system, the unit must stand turned off with the doors open for at least 12, or better 24 hours. A shorter defrosting may not eliminate the ice jam.
Is it possible to use a refrigerator if it does not freeze the top?
Short-term - yes, but you cannot store perishable foods in the upper chamber. However, long-term operation in this mode is dangerous for the compressor, which will wear out without shutting down, which can lead to its combustion.
What does the flashing temperature indicator mean?
Flashing usually indicates that the temperature in the chamber is above the established norm. If, after loading the products and closing the door, the indicator does not stop flashing after a few hours, this indicates a malfunction of the cooling system.