The situation when the refrigerator Bosch continues to hum, ignoring the set temperature, causes concern for any owner. Constant operation of the compressor not only increases energy bills, but also creates intrusive noise that interferes with rest. Most often, this indicates that cooling system cannot achieve the specified parameters or sensors transmit incorrect data to the controller.
Modern models, such as Bosch Serie 6 or Bosch KGNare equipped with complex electronics that control cycles of on and off. If the unit operates without interruption, this may be either a temporary failure after defrosting or a serious technical malfunction. It is important not to panic, but to consistently analyze the operating conditions and external signs of failure.
In this article we will analyze in detail the mechanical and electrical reasons for continuous operation, and also explain when a technician’s intervention is necessary, and when the problem can be solved independently. Understanding the principles of operation compressor will help you quickly diagnose a malfunction.
The influence of external temperature and Super Freeze mode
The first thing you need to check before looking for a breakdown inside the unit is external factors. If the room where the refrigerator is located is too hot, or it is exposed to direct sunlight, heat exchange it is violated. The unit simply does not have time to cool down to the required temperature, so the sensor does not give the command to turn off the engine.
It is also worth paying attention to the activated function Super Freeze (Super Freeze). In models Bosch this mode is often turned on automatically when loading a large volume of warm products, but sometimes the user forgets to turn it off. In this mode, the refrigerator operates continuously, ignoring standard cycles.
Attention! ⚠️ If you have turned on the fast freezing mode, do not forget to turn it off after 24 hours or after the food has frozen, otherwise the compressor may overheat due to prolonged operation without stopping.
Check the tightness of the door. If seal is worn out or dirt has adhered to its surface, warm air constantly enters the chamber. The temperature sensor detects an increase in degrees and forces the motor to work in an increased mode, trying to compensate for the heat influx.
Malfunctions of the thermostat and temperature sensors
One of the most common reasons why the refrigerator Bosch does not turn off is the failure of the thermostat. This mechanical or electronic component is responsible for opening the compressor power circuit when the desired temperature is reached. If the contacts are “stuck” or a mechanism breakdown occurs, the circuit does not open and the engine hums endlessly.
In more modern models with the system No Frost instead of a classic thermostat, electronic sensors (thermistors) are used. They transmit data to the control board. If the thermistor sends an erroneous signal that the chamber is too warm, the board will keep the compressor on. Diagnostics of such elements requires the use of a multimeter to check the resistance.
- 🔧 Mechanical thermostat: often fails due to loss of tightness of the bellows or oxidation of the contacts.
- 📉 Adjustment offset: sometimes the thermostat knob accidentally moves to the “Maximum” position, which causes the refrigerator to work at the limit capabilities.
- ⚡ Electronic sensor: may fail due to voltage surges or natural aging of elements.
To replace the thermostat in older models Bosch often it is necessary to dismantle the plastic lining inside the refrigerator compartment.
How to check a thermostat with a multimeter?
To check a mechanical thermostat, you need to remove the wires from it and ring the contacts. At room temperature they should “ring” (resistance is close to zero). If you place the sensing element in cold water (about 0°C), the circuit should open. Lack of response indicates a malfunction.
Problems with circuit tightness and refrigerant leakage
If the refrigerator hums, but does not cool or cools very little, and the compressor does not turn off, there is a high probability of a leak. freon. The refrigerant circulates through the system, picking up heat. When its quantity becomes critically low, the unit is physically unable to cool the chambers to the specified values, so it works 24/7, trying to somehow maintain the temperature.
A leak can occur anywhere: in the foamed part of the body, in the evaporator or at the joints of the tubes. Often the cause is metal corrosion or mechanical damage due to careless defrosting (for example, piercing the ice with a knife). In models Bosch with a system No Frost the leak is more difficult to notice visually, since the evaporator is hidden behind a plastic panel.
Attention! ⚠️ Trying to fill the refrigerator with freon yourself without finding and eliminating the leak will only lead to a temporary effect. After a few days, the gas will leave again, and the compressor will burn out from running “dry.”
Diagnostics of a leak includes a visual inspection for oily stains (freon often comes out along with the oil) and checking the pressure in the system with a pressure gauge station. This is a job for a professional who has the appropriate equipment and a license to work with refrigerants.
Clogged capillary tube and compressor malfunction
Another technical reason for continuous operation is clogging of the capillary tube. This is a thin element through which freon is supplied to the evaporator. If there is moisture in the system, it turns into an ice plug, or debris from oil breakdown gets in there, the circulation of the refrigerant is disrupted. The pressure increases, the compressor operates with overload, but cooling does not occur.
It is also worth considering the possibility of wear of the compressor itself. Over time motor-compressor loses its performance: the piston group wears out, the valves no longer hold pressure. In this state, the unit may hum for days, but not create the necessary pressure for a normal cooling cycle.
| Symptom | Possible cause | Necessary actions |
|---|---|---|
| The refrigerator is humming, but it is cold only at the back wall | Freon leak | Call a technician to find a leak and refill |
| The compressor is hot, clicks, but does not start or does not stall | Malfunction of the starting relay or compressor | Replacement of the starting-protective relay or motor |
| The chamber is warm, the condenser (grid at the back) is cold | Clogged capillary tube | Purge the system or replace the filter-drier |
| The sound of liquid flowing is heard, but there is no cold | Air lock or lack of freon | Evacuation and refilling the system |
If you notice that the condenser (black grille on the back) remains cold while the engine is running, this almost always indicates a problem with the circulation of refrigerant or lack thereof. Normal operation implies that the condenser should be warm or hot.
☑️ Primary diagnostics of the refrigerator
Failures in the operation of the electronic control module
Refrigerators Bosch electronically controlled (often have a display on the door) depend on the software and serviceability of the control board. If the module is “buggy”, it can send a continuous signal to start the compressor, even if the temperature sensors indicate normal. This often happens after power surges.
In some cases, it helps resetting the error by completely disconnecting the device from the network for 15-20 minutes. If, after turning on, the refrigerator began to operate in normal cyclic mode, it means that a single software failure has occurred. However, if the problem recurs, diagnostics of the board is required.
Error codes, for example, E01 or E09, may light up on the display, which indicate problems with the sensors or communication with the module. The decoding of the codes depends on the specific series Bosch, so it is important to check the instructions or databases of service centers.
When you need to call a specialist
Independent repair is only possible if you replace the seal, thermostat (in simple models) or check the electrical circuits. However, there are situations where the intervention of an unqualified user can lead to permanent breakdown of the unit. If you do not have the skills to work with refrigeration equipment, it is better not to risk.
It is strictly not recommended to open a sealed circuit, change the compressor, or try to find a leak without professional equipment. This is not only difficult, but also dangerous, since the system contains oil and gas under pressure.
⚠️ Attention: Information about diagnostics is for informational purposes only. The design of Bosch refrigerators may vary depending on the year of manufacture and model. Before starting any disassembly work, make sure that the device is disconnected from the power supply and check the technical data in the manufacturer's official documentation.
If, after checking all external factors and simple settings, the refrigerator continues to work without interruption, and the temperature inside does not drop, this is a sure sign of an internal malfunction. Delay in repairs can lead to failure of the expensive compressor, which is the “heart” of your refrigerator.
Frequently asked questions (FAQ)
Why does the new Bosch refrigerator work without interruption on the first day?
This is normal. When you first turn on the unit, it takes time (sometimes up to 24 hours) to cool the entire internal volume and enter operating mode. During this period, the compressor may not turn off.
Is it possible to operate the refrigerator if it does not turn off?
For a short time, it is possible, but this will lead to increased energy consumption and wear on the compressor. If the reason is a freon leak, long-term dry operation will quickly damage the motor.
How can you tell that the thermostat is broken and the freon has not run out?
If the refrigerator freezes too much (everything freezes even in the refrigerator compartment) and does not turn off, most likely the thermostat is stuck. If it hums, but there is little or no cold, most likely there is a freon leak or a blockage.
Where is the thermostat in a Bosch refrigerator?
In older models it is located inside the refrigerator compartment, often hidden by a plastic cover or located next to the light bulb. In models with electronic control, its function is performed by sensors located at different points in the chambers.