The situation when Bosch refrigerator the food begins to cool too intensively, especially in the upper compartment, often confuses owners. Instead of fresh vegetables and fruits, you find an ice crust, and the milk turns into a frozen briquette, which requires immediate attention. Modern models of the German brand are equipped with sophisticated electronics, but even reliable systems No Frost or static cooling can malfunction.
Excessive freezing of the upper chamber is not just inconvenience, it is a signal that thermoregulation violated. Unlike the bottom freezer, where low temperatures are the norm, the refrigerator compartment must be maintained between +2 and +5 degrees Celsius. If food freezes at the back wall or on the shelves, it means that the control system “thinks” that it is too warm inside and forces the compressor to work without stopping.
In this article we will analyze in detail the mechanical and electronic causes of such a malfunction. We will focus on brand-specific design features, such as sensor placement and fan operation algorithms. Understanding exactly how your unit distributes cold air will help you quickly identify the source of the problem and avoid costly repairs in a service center. Bosch design features, such as the location of sensors and fan operation algorithms. Understanding exactly how your unit distributes cold air will help you quickly identify the source of the problem and avoid costly repairs at a service center.
Checking the temperature settings
Before looking for complex technical faults, it is necessary to eliminate the human factor. Users often accidentally change settings, especially if the control panel is located in a visible place and children or pets have access to it. In models with electronic control temperature mode can be set to minimum values (Max Cold or Super Cool), which forces the unit to work at the limit.
Pay attention to the indicators on the display. If the snowflake icon or “Super Freeze” is lit, this means that the accelerated cooling mode is turned on. In this state compressor works continuously, ignoring standard rest cycles, which inevitably leads to the formation of ice in the refrigerator compartment. To normalize operation, it is enough to disable this function; this is usually done by long pressing the corresponding button.
It is also worth checking whether the basic temperature settings have been reset. In some models Bosch with a digital display, you can manually set the value to +1 or even 0 degrees, which is incorrect for storing most products. Normal operation of the refrigerator is restored when the value is set to +4°C. If after resetting the settings the problem persists, then the problem is not in the software, but in the hardware.
In this case, a simple reboot of the device often works wonders. Disconnect the device from the power supply for 10–15 minutes so that the capacitors are completely discharged and the controller resets errors. After turning on, re-set the necessary parameters.
⚠️ Attention: If you have reset the settings to factory settings, but the refrigerator continues to freeze very cold, under no circumstances leave food in the chamber unattended - they may spoil due to deep freezing.
Malfunctions of the thermostat and temperature sensors
One of the most common reasons why Bosch refrigerator it gets very cold is the failure of the thermostat or temperature sensor. In mechanical models, the thermostat is responsible for regulation - a device that opens the electrical circuit when the set temperature is reached. If its contacts “stick” in a closed state, the compressor does not receive a signal to stop and continues to pump in cold.
In modern models with a system No Frost and electronic control, the thermostat function is performed by air sensors (thermistors). They are located inside the cameras and transmit data to the main control module. If the sensor “lies” and shows that the chamber is +10°C, although in reality it is already -5°C, the “brains” of the refrigerator will drive the motor until everything turns to ice. Replacing such an element requires disassembling the internal lining.
Diagnostics of the sensor is often carried out by measuring its resistance with a multimeter at different temperatures. However, for the average user it is easier to proceed by elimination. If you hear that the motor is humming constantly, without turning off for hours, and slush forms in the upper chamber, with a 90% probability the problem is in the temperature control circuit.
How to check a mechanical thermostat?
To check a mechanical thermostat, it must be removed from the housing (after first disconnecting the refrigerator from the network). The ends of the wires are connected directly. If the compressor starts, then the problem is in the thermostat and it needs to be changed. If it doesn’t start, look for the reason in the start relay or the motor itself.
It is also worth mentioning the defrost sensor, which indirectly affects the temperature. If it is faulty, the system may incorrectly calculate defrost cycles, which leads to the accumulation of ice on the evaporator and its subsequent entry into the chamber when blowing. This is a typical problem for older models Bosch with the system No Frost.
Problems with the Air Control damper and the blowing system
In two-chamber refrigerators Bosch with a full system No Frost cold enters the upper chamber from the freezer through a special channel. The damper regulates the volume of supplied air. Air Control. If this mechanism gets stuck in the open position or the damper servo drive fails, cold air flows freely and in large volumes into the refrigerator compartment.
Visually this is manifested by the fact that the products lying directly opposite the air duct opening (usually on the top shelf near the rear wall) are covered with frost, while on the lower shelves the temperature may be normal. The damper is controlled electronically, and if it breaks, the entire assembly often needs to be replaced. It is difficult to repair a plastic mechanism yourself, as it often cracks from frost.
Another reason is a violation of the tightness of the door seals. If the rubber seal does not fit tightly, warm, moist air constantly enters the chamber. Sensors detect an increase in temperature and give a command for enhanced cooling. As a result, the refrigerator wears out, trying to compensate for the heat influx, which leads to freezing.
To eliminate this problem, dismantling the rear panel of the refrigerator compartment is often required. There is the channel itself and the damper motor. Before replacing, it is recommended to check the electrical contacts suitable for the motor - they may have oxidized or been damaged by vibration.
Freon leakage and compressor operation
Paradoxically, a refrigerant leak (freon) can also lead to local freezing. When the amount of gas in the system decreases, the compressor begins to work almost non-stop, trying to reach the set temperature. Since the cycle is continuous, the evaporator freezes deeper than usual, and the cold “breaks through” into the chamber more strongly.
It is difficult to determine the leak yourself, but there are indirect signs. Pay attention to the operation of the motor: if it hums 24 hours a day without rest cycles, and the condenser (grid at the back) is only partially warm or completely cold, this is a sure sign of a lack of freon. In such cases, the refrigerator may become very cold at the back wall, where the evaporator is located.
Repair in this case is possible only in a specialized workshop. The technician must find the leak (often these are foamed areas or solder joints), solder it, evacuate the system and charge it with new refrigerant. It is strictly forbidden to add freon “by eye” yourself - this will lead to the final failure of the compressor.
| Symptom | Probable cause | Nature of motor operation | Difficulty of repair |
|---|---|---|---|
| Ice all over the chamber | Thermostat/sensor is faulty | Works without stopping | Average |
| Ice on the back wall | Stuck Air Control damper | Cyclic, but frequent | High |
| Ice crust on food | Super Cool mode enabled | Continuous operation | Low (setting) |
| Frost on the evaporator | Freon leakage | Constant operation, quiet hum | High (master) |
The influence of the fast freezing mode
Many owners forget that they have turned on the “Super Frost” function to quickly cool a large number of products. In this mode operation algorithm the refrigerator changes: it ignores the temperature in the refrigerator compartment and focuses on maximum cooling of the freezer, but due to the connectivity of the systems, the cold actively goes up.
If you forget to turn off this mode, the refrigerator will operate in emergency mode until until you cancel the command or the timer runs out (usually several hours, but in some models without a timer - indefinitely). Check the control panel: the function indicator should be lit if the mode is active.
It is also worth considering that loading a large amount of warm food can cause a long cooling period. However, if you put one pot of soup, and the refrigerator is “humming” for the second day, it’s not the food, but a breakdown.
⚠️ Attention: Long-term operation in the maximum freezing mode leads to accelerated wear of the compressor and freezing of the evaporator, which may require long-term defrosting (up to 24 hours) to restore normal operation.
When you need to call a technician
There are a number of situations when independent repair Bosch refrigerator is not only ineffective, but also dangerous. If you have checked the settings, made sure that the seals are intact and that there are no special modes enabled, but the problem persists - most likely, you need to replace electronic components or refill with freon.
A particularly alarming signal is the appearance of oil around the compressor or a change in the color of smoke from the pipes (if this is observed during disassembly). This indicates serious problems with the refrigeration circuit. Also, the help of a specialist is needed if you do not have experience with a multimeter and electrical circuits.
Modern models Bosch often have self-diagnosis. The error may be indicated by flashing temperature indicators or a code on the display. Deciphering these codes requires access to the technical documentation of the specific model that the technician has in the database.
☑️ Checklist before calling the technician
Do not ignore the problem of severe freezing. In addition to food spoilage, this leads to increased energy consumption and reduced service life of an expensive compressor. Timely diagnostics allows you to solve the problem by replacing an inexpensive sensor, avoiding replacing the motor.
Frequently asked questions (FAQ)
Why does the water in the upper chamber freeze in a Bosch refrigerator?
This is the main sign that the temperature in the chamber has dropped below 0°C. Reasons: the thermostat is faulty, the air supply damper is stuck, or the super cooling mode is turned on. Diagnostics of the thermoregulation system is required.
Is it possible to replace the temperature sensor in Bosch yourself?
Yes, if you have the skills to work with a tool and a multimeter. The sensor is located behind the back wall inside the camera. However, access to it often requires partial disassembly, which can break the seal if assembled incorrectly.
How long should a refrigerator compressor rest?
In normal mode, the compressor operates for about 10-15 minutes and rests for 20-30 minutes (the operating coefficient is about 30-40%). If it hums constantly or turns on too often (every 2 minutes), this is a malfunction.
What should you do if, after defrosting, the refrigerator starts to get very cold again?
If complete defrosting (disconnecting from the network for a day) did not help, then the problem is of a technical nature (sensor, damper, freon). A software failure is also excluded, since defrosting has already been carried out.