Owners of premium equipment are often faced with a situation where the upper part of the unit suddenly stops cooling, while the lower compartment continues to function normally. If you find that Bosch refrigerator does not work in the upper chamber, this does not always mean a fatal breakdown of the compressor or the need for expensive service. In most cases, the problem lies in a violation of the circulation of cold air or malfunctions in the control system, which can be diagnosed independently.
Modern models Boschequipped with a system No Frost or Multi Airflowrepresent are complex engineering structures where the temperature regime is controlled electronically. The absence of cold from above while the bottom is running often indicates that the refrigerant is circulating but not reaching the evaporator in the upper circuit, or the sensors are transmitting incorrect data to the controller. Understanding the operating principle of your model will help you quickly localize the fault.
Before calling a technician, it is worth conducting a basic check, excluding simple household factors. Sometimes the reason is simple: the ventilation holes are clogged with food or the temperature settings are lost after a power surge. A careful inspection and consistent diagnostics will help save time and money.
Checking settings and simple causes
The first step in diagnosing a situation where the upper chamber does not freezeis to eliminate the human factor and simple mechanical obstacles. Often, users accidentally touch the control panel when changing operating modes, or pack shelves tightly, blocking air flow paths. In models with No Frost this is a critical moment, since cold air is forced in.
Pay attention to the following points that can simulate a serious breakdown:
- 🌡️ Check the set temperature: it may have been accidental increased to +10°C or higher as a result of a power surge.
- 🚪 Make sure that the upper chamber door fits tightly and the seal is not damaged, allowing warm air to pass through.
- ❄️ Inspect the back wall: if you see a crust of ice, the defrosting system may have malfunctioned and the channels are clogged ice.
- 🔌 Check whether the power cord has come loose or whether the machine in the panel has been knocked out, even if the light inside is on (in some models the lighting is powered separately).
If a visual inspection does not reveal obvious reasons, and the products in the upper part begin to deteriorate, it is necessary to proceed to a more in-depth diagnosis of the unit components.
Malfunctions of the defrost and evaporator system
One of the most common reasons why the upper chamber does not work in refrigerators Bosch with a system No Frostis a malfunction of the defrost system. Ice accumulating on the evaporator blocks the fan, and cold air stops flowing into the refrigerator compartment, remaining only in the freezer compartment (which is usually located below or at the back).
The defrost system includes several key elements, failure of any of which leads to icing:
- ❄️ Defrost heating element: a heating element that periodically turns on to melt the ice on the evaporator.
- ⏱️ Timer or electronic module: controls the cycles of turning on and off the defrost mode.
- 🌡️ Defrost sensor: monitors the temperature evaporator and signals the module to turn on the heating element.
If Bosch refrigerator stops cooling from above, but it hums and works, most likely the fan has simply hit an ice plug. In this case, the unit must be completely defrosted within 24 hours (minimum 24 hours) with the doors open. If, after switching on, the problem recurs 1-2 weeks later, it means that one of the elements of the defrost system is faulty and requires replacement.
☑️ Diagnostics of the defrost system
Problems with the fan and air circulation
In models with forced a special fanis responsible for air circulation for cooling the upper chamber. If it stops, the cold remains in the evaporator area (usually the freezer compartment) and only warm air from the room enters the upper area. This is a classic situation when “the bottom is freezing, but the top is not.”
The reasons for the fan stopping can be different:
- 🧊 Freezing of the blades: moisture gets on the shaft and freezes, blocking rotation.
- ⚙️ Bearing wear: the fan begins to hum, squeak and eventually stops.
- ⚡ Wiring break or motor malfunction: the electrical signal does not reach the fan motor.
To check, you need to get to the fan (usually it is located behind the back panel in the freezer or in the upper part of the refrigerator compartment, depending from model Bosch). When you turn on the refrigerator, you should hear a characteristic noise of operation or feel the flow of air with your hand brought to the holes in the back wall.
⚠️ Attention: If you hear extraneous noise, crackling or humming, but the cold does not come, do not try to turn the fan blades by force. This can lead to the final destruction of the bushings or breakage of the blades.
Failures in the operation of temperature sensors
Refrigerator electronics Bosch rely on the readings of temperature sensors. If upper chamber sensor transmits incorrect data (for example, it shows that it is -5°C, although in fact it is +15°C), the compressor will not turn on for cooling, since the control module “believes” that the norm has been reached.
Symptoms of sensor failure:
- 📉 The compressor works very rarely or does not turn on at all, although the chamber is warm.
- 📈 The compressor works continuously, trying to cool the chamber, but the sensor “does not see” changes.
- 💡 The display (if any) may display incorrect temperature values.
Replacing the sensor is a technically simple procedure, but requires access to the insides of the unit. Sensors Bosch often have a specific resistance, so using universal analogues is not recommended - it is better to order an original spare part according to the catalog number of your model.
How to check a sensor with a multimeter?
To check the temperature sensor, it must be removed and “ringed” with a tester in resistance measurement mode. At room temperature, a working sensor will usually show a resistance in the range of 2 to 5 kOhm (the exact value depends on the model). When heated in your hands, the resistance should change smoothly. If the device shows an open circuit (infinity) or a short circuit (0 Ohm), the sensor is faulty.
Freon leakage and compressor malfunctions
Although a refrigerant leak more often leads to a complete lack of cold, in some cases, especially in double-circuit systems or with partial blockage of the capillary tubes, a situation may occur when The upper chamber does not freeze, and the freezer still holds cold. This is a more complex and expensive scenario.
Signs of problems with the refrigerant or compressor:
- 🔇 The compressor turns on for a short time and turns off, or hums, but does not start.
- 🌡️ The condenser grille at the back of the refrigerator remains cold (normally it should be warm).
- 🧊 A “snow coat” forms in the freezer only at the freon entrance, and the rest is warm.
If you suspect a freon leak or a compressor breakdown, independent repair is impossible. You need to call a specialist with equipment to evacuate the system, refill with freon and solder the tubes. Attempts to add freon “by eye” without looking for a leak will only lead to a temporary effect.
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| The top is warm, the bottom is freezing, there is no noise fan | The fan is faulty or frozen | Average |
| The top is warm, there is ice on the back wall | Failure of the defrost system (heating element, timer) | Medium |
| Compressor is silent, no light | Problem with power supply or module | Low/High |
| Compressor hums, but does not cool nowhere | Freon leak or compressor wedge | High (requires a technician) |
Electronic control module and its role
The brain of any modern Bosch refrigerator is the electronic control module. It is he who receives signals from sensors and gives commands to the compressor, fans and heating elements. Power surges in the network can lead to “glitches” of the board when it stops processing commands correctly.
Sometimes the module requires flashing or replacing individual elements (relays, capacitors). If you see error codes on the display (for example, E01, F02, etc.), this is a direct indication of which unit is not working. The decoding of the codes can be found in the instructions for the specific model Bosch.
It is important to consider that electronics are sensitive to humidity. If the defrost system did not operate correctly for a long time, water could flow onto the control board, causing corrosion of the contacts. In such cases, a visual inspection of the board may reveal blackening or oxides.
⚠️ Attention: The characteristics and location of electronic components may vary depending on the year of manufacture and series of the refrigerator. Always check the diagram of your specific model in the official user manual before tampering with the electrical part.
When you need to call a specialist
Despite the ability to self-diagnose some faults, there are situations where the risk of damage to the unit is too high. If Bosch refrigerator does not work in the upper chamber due to problems with the tightness of the circuit or complex electronics, it is better to trust the professionals.
List of situations for calling a technician:
- 🛠️ Need for replacement compressor or freon charging (license and equipment required).
- 💳 Suspicion of a malfunction of the main control module (diagnosis with an oscilloscope required).
- 🔌 Detection of mechanical damage to tubes or condenser.
- 📜 The unit is under warranty (opening the seals on your own will void the warranty).
Timely contacting a specialist can prevent damage to products and more expensive repairs in the future. The technician will be able to determine exactly why the upper chamber is not freezingusing professional diagnostic equipment.
How much does the repair cost?
The cost of repair depends on the model and the malfunction. Replacing a sensor or fan usually costs less than repairing a compressor or replacing a control board. The exact price can only be found out after diagnostics.
Frequently asked questions (FAQ)
Why does the top chamber in a Bosch refrigerator not work, but the freezer freezes?
Most often this indicates a problem with air circulation. In No Frost systems, cold is produced in the freezer and driven upward by a fan. If the fan is stopped, the channels are clogged with ice, or the temperature sensor of the upper chamber is faulty, the cold will not reach there, although the freezer will work properly.
How to defrost a Bosch refrigerator correctly if it has stopped cooling?
You must completely unplug the unit, remove all food and leave the doors open for at least 24 hours. Place towels as there will be a lot of water. Do not use a hair dryer or knife to crush ice as this may damage the evaporator. After defrosting, turn on the empty refrigerator for 2-3 hours to set the temperature.
Could the sensor be to blame if the refrigerator is humming but not cooling from above?
Yes, a faulty temperature sensor can “lie” to the control module, reporting that it is already cold enough in the chamber. In this case, the compressor will not turn on for cooling, or will operate in the wrong mode. It is necessary to check the resistance of the sensor with a multimeter.
What to do if an ice crust has formed on the back wall of the upper chamber?
This is a sign of a violation of the defrost system. Ice blocks the flow of cold air. It is necessary to carry out complete defrosting (24 hours). If ice appears again after a week, the defrost heating element, timer or defrost sensor has burned out. The faulty element needs to be replaced.