The situation when the refrigerator Bosch does not stop the cooling cycle can frighten the owner. The hum of a compressor that does not subside for hours often indicates that the unit has entered emergency operation or is trying to compensate for the loss of cold. This is not just noise that interferes with rest, but also a direct threat to the safety of food, as well as the life of the device itself. If you notice that the motor is running without interruption, you must immediately carry out initial diagnostics.
Modern models, such as the series Bosch Serie 6 or Bosch Serie 4, are equipped with smart electronics that should control temperature conditions. However, even reliable German technology is subject to external factors and natural wear and tear. Understanding why your refrigerator does not turn off will help you avoid costly repairs or complete replacement of expensive equipment.
In this article we will analyze in detail the mechanical and electrical causes of the malfunction. We will look at simple steps that you can do yourself, and situations where you cannot do without calling a specialist. Ignoring the problem in the early stages, it often leads to failure of the compressor, the replacement of which is not economically feasible.
Primary diagnostics: checking the temperature conditions
Before looking for complex breakdowns, it is worth eliminating trivial operating errors. Often the reason that the refrigerator Bosch does not turn off is the incorrectly set temperature. Users, wanting to cool a large number of products faster, set the thermostat to maximum. As a result, the system cannot reach the set stopping point, and the motor wears out.
Check the settings in the electronic menu or the position of the mechanical knob. For the main camera, the optimal value is considered to be from +3 to +5 degrees Celsius. If you have the SuperCooling or “Super Freeze” mode enabled, the device will work constantly until you forcefully disable this function. It is also worth remembering whether you loaded hot or warm food into the chamber, which sharply increased the internal temperature.
⚠️ Attention: Prolonged operation of the compressor at maximum power leads to overheating of the windings and can cause thermal breakdown of the insulation.
Pay attention to the location of the thermometer if you are using an external device for testing. Temperatures may vary in different areas of the refrigerator. Sensors in the models Bosch KGN read readings at specific points, and if it is warm there, the cycle will not be interrupted. Make sure that food does not block the air channels, interfering with circulation.
Problems with the tightness of the chamber and the seal
One of the most common reasons for continuous operation is a violation of the tightness of the internal circuit. If warm air from the room constantly penetrates inside, sensors detect an increase in temperature and command the compressor to work more actively. First of all, you need to inspect rubber seal the doors. Over time, the rubber loses its elasticity, cracks or deforms.
Check the door for a tight fit. This can be easily done using a sheet of paper: press it between the door and the body around the perimeter. If the sheet is removed without resistance or falls out, the seal is broken. In models Bosch NoFrost even a small gap leads to constant freezing of the evaporator, which forces the cooling system to work in enhanced mode.
Also the reason for loose closure can be:
- 🧊 Stuck food or dishes that prevent the door from closing tightly.
- 🧊 Warped hinges caused by heavy weight on the door.
- 🧊 Contamination of the magnetic seal strip with grease or crumbs.
- 🧊 Uneven installation of the refrigerator itself when it is tilted forward.
If the door is skewed, it can be adjusted by tightening the hinge mounting bolts. However, if the rubber is severely worn or torn, a complete replacement of the seal will be required. It is better to order spare parts using the exact model number indicated on the nameplate inside the chamber.
Malfunctions of the defrost system and sensors
In refrigerators with the system NoFrost the proper operation of the defrost system is critically important. If the evaporator becomes overgrown with a “coat” of ice, the cold ceases to flow effectively into the chamber. The compressor tries to compensate for the lack of cold by working non-stop. The main elements that fail in this circuit are A defrost heating element, a thermal fuse or a defrost sensor.
The defrost sensor is responsible for turning the heater on and off. If it is “lying” or shorted, the system may not enter defrost mode on time. As a result, ice blocks the fan and air circulation stops. In models Bosch with electronic control, this problem is often signaled by a flashing temperature indicator or an error code on the display.
Typical symptoms of a malfunction in the defrost system:
- ❄️ The hum of the fan is heard, but the cold does not enter the chamber.
- ❄️ A layer of ice or frost is visible on the back wall.
- ❄️ The compressor works constantly, but the temperature inside is higher than normal.
- ❄️ The appearance of puddles of water under the refrigerator or in the pan.
⚠️ Attention: Replacing the heating element or sensors yourself requires disassembling the internal panel and skills in working with a multimeter. Inexperienced intervention can damage the plastic elements of the case.
How to check the defrost heating element?
To check the heating element, you need to “ring” it with a multimeter. The resistance of a working heater is usually from 200 to 600 Ohms. If the device shows an open circuit (infinity) or a short circuit (zero), the element must be replaced. It is also important to check the integrity of the wires going to the heater, as they often rot at the bend points.
Failures in the operation of the thermostat and electronic module
In older models of refrigerators Bosch a mechanical thermostat is responsible for turning off the motor. This is a device that opens the electrical circuit when a set temperature is reached. If the capillary tube of the thermostat has lost sensitivity or the contacts inside are stuck, the circuit will not break and the compressor will hum continuously. In modern models, this function is performed by an electronic control module that reads data from temperature sensors.
If a temperature sensor (thermistor) fails, it can transmit incorrect data about the high temperature inside the chamber to the control board. The “brain” of the refrigerator, receiving a false signal, forces the compressor to work without rest. Replacing the sensor is a quick procedure, but requires accurate diagnostics, since there may be several sensors in the system (in the refrigerator compartment, in the freezer, on the evaporator).
Below is a table with approximate symptoms of malfunction of various control elements:
| Element | Symptom breakdown | Probability of breakdown | Difficulty of repair |
|---|---|---|---|
| Mechanical thermostat | The refrigerator does not turn off at all or does not turn on | High (for old models) | Low |
| Thermal sensor (NTC) | Incorrect temperature readings, errors on the display | Average | Low |
| Control board | Chaotic operation, lack of response to buttons | Low | High |
| Start relay | Clicks when starting, motor does not start or does not stall | Medium | Low |
Diagnostics of the electronic module at home is almost impossible without special equipment. If you have ruled out all mechanical causes and sensor problems, the control board is most likely faulty. In this case, it requires flashing or replacement.
Refrigerant leak and problems with the compressor
The most serious and expensive problem is a freon leak. If a microcrack has formed in the system, the refrigerant gradually evaporates. The pressure in the circuit drops and the compressor cannot gain the required power to achieve the target temperature. In an attempt to compensate for the lack of freon, the motor runs constantly, but does not produce cold. This is a classic scenario when the refrigerator “threshes” for days.
Another critical situation is the loss of performance of the compressor itself. The engine life of the unit may be exhausted, the valves inside the compressor may be worn out. In this case, it hums, but does not create the necessary pressure. Only a master can determine this using a manometric manifold, measuring the discharge and suction pressure.
Signs of a freon leak or problems with the compressor:
- 🔥 The compressor is very hot to the touch (not just warm, but scalding).
- 🔥 It is warm in the refrigerator compartment, but in the freezer the food begins to thaw.
- 🔥 There is no characteristic heating on the condenser tubes (at the back or on the sides).
- 🔥 The sound of gurgling or hissing is heard inside the system.
⚠️ Attention: Refilling with freon and searching for leaks requires a license and special equipment. Trying to solder pipes or refill gas on your own is strictly prohibited - this is dangerous to life and health.
☑️ Checklist before calling a technician
The influence of external factors and operating conditions
Sometimes the reason lies not in the breakdown, but in the conditions in which the device is placed. Refrigerators Bosch, like any equipment, have a climate class. If a device designed for a temperate climate (SN, N) is installed in an unheated room or, conversely, next to a hot stove, it will not be able to turn off correctly. Heat transfer is disrupted, and the system operates at its limit.
It is also important to consider the distance to the walls. For normal operation of a condenser located on the rear wall or in the side walls, free air flow is necessary. If the refrigerator is pushed tightly against the wall or is filled with things on all sides, the heat is not removed and the compressor does not turn off. The minimum gap should be at least 5-10 cm.
Do not forget about the seasonal factor. In summer, when the ambient temperature in the apartment is high, the refrigerator runs longer and more often. This is normal operation and not a breakdown. However, if it does not turn off even at night, when the house is cool, you should be wary. In winter, if the refrigerator is placed on the balcony, the oil in the compressor may thicken, which will also lead to incorrect operation.
Frequently asked questions (FAQ)
How long should a Bosch refrigerator operate normally?
In normal operation, the cooling cycle is approximately 15-20 minutes, followed by a pause (off-time) lasting from 30 to 60 minutes. The working time ratio usually does not exceed 40-50%. If the refrigerator works for 20 minutes and rests for 10, this is already a cause for concern.
Can the refrigerator not turn off due to power surges?
Yes, power surges in the network can damage the electronic control board or the compressor starting relay. As a result, the relay may become stuck closed, supplying power to the motor continuously. It is recommended to use a voltage stabilizer or surge protector to protect equipment.
What to do if a Bosch refrigerator makes a loud hum and does not turn off?
A loud hum may indicate that the compressor is running dry due to a freon leak or problems with the fan in the NoFrost system. In the first case, the motor overheats. It is necessary to immediately disconnect the device from the network and call a specialist so as not to completely burn out the compressor.
Is it true that a new refrigerator should work for a long time when first turned on?
Yes, when first started or after long-term transportation, the refrigerator takes time (from 4 to 12 hours) to reach operating temperature and stabilize processes. During this period, the compressor can work almost without stopping. It is normal if after reaching a temperature it starts to turn off.
Is it possible to operate the refrigerator if it does not turn off?
For a short time - you can while you are waiting for the technician. Long-term operation in this mode will lead to burnout of the compressor windings, melting of the wiring and damage to the products. If you see that the temperature inside does not drop and the motor does not stop for more than a day, it is better to turn off the device and unload the products.