The situation when Bosch refrigerator stops turning off is familiar to many owners of household appliances. You notice that the compressor is humming non-stop, the door is hot, and the temperature inside the chamber may even be below normal. This is not just an annoying noise, it is a signal that the cooling system is working in emergency mode, trying to achieve the set parameters, but cannot do so. Ignoring the problem can lead to engine burnout or food spoilage.
Most often, the reason lies in a violation of the tightness of the circuit or failure of electronic sensors. Modern models Side-by-Side and two-chamber Bosch units are equipped with a complex self-diagnosis system, which, when a heat or refrigerant leak is detected, causes the motor to wear out. It is important to understand that in some cases, equipment tries to “save” products by sacrificing the life of the compressor.
In this article we will analyze in detail the mechanical and electrical causes of the malfunction. You will learn how to carry out initial diagnostics yourself and in what cases calling a specialist becomes inevitable. Do not rush to throw away the equipment - often the problem can be solved by replacing the seal or adjusting the thermostat.
No Frost system malfunctions and cold leakage
One of the most common reasons for the continuous operation of the compressor in models with the system No Frost is a violation of the chamber seal. If warm air from the room constantly enters the chamber, the temperature sensor records the increase in degrees and gives the command to the motor not to stop. First of all, you need to check the condition of the sealing rubber around the perimeter of the door.
Over time, the rubber dries out, cracks, or simply becomes contaminated with grease, causing the door to not fit tightly. The problem may also lie in skewed hinges, especially if heavy pots were placed on the shelves. Check whether the door closes tightly using a simple test with a sheet of paper: squeeze the sheet between the seal and the body - if it pulls out easily, the seal is broken.
⚠️ Attention: If you find cracks or tears in the seal, do not try to seal them with superglue. This is a temporary solution that will ruin the rubber structure. A complete replacement of the circuit will be required.
Additionally, it is worth checking the condensate drainage channels. If the drainage hole is clogged with ice or debris, the moisture does not leave, freezes and creates a “thermal cushion” that interferes with normal cooling. The system will work in enhanced mode, trying to break through this barrier.
- 🧊 Check the tight fit of the door around the entire perimeter.
- 🚪 Inspect the hinges for distortion or sagging.
- 🧹 Clean the drainage hole from ice and dirt.
- 🌡️ Make sure that the products do not interfere with the door closing tightly.
☑️ Diagnosis of tightness
Problems with the thermostat and temperature sensors
In older models of Bosch refrigerators, the mechanical one is responsible for temperature control thermostat. This is a device with a capillary tube that senses heat in a chamber. If the thermostat fails and gets stuck in the "on" position, the compressor will run continuously even when it's already deep freeze inside. In such cases, freezing of the rear wall is often observed.
Modern digital models Bosch Serie 4 or Serie 6 use electronic sensors (thermistors). They transmit data to the control module. If the sensor “lies” and shows that the chamber is warm, although in fact it is cold there, the controller will not give the command to turn off the motor. Replacing such an element requires disassembling the internal panel and having a multimeter to check the resistance.
Sometimes the problem is not in the sensor itself, but in oxidation of the contacts or a break in the wiring going to it. The humid environment inside the chamber promotes corrosion of connections. In this case, the signal simply does not reach the control board, and it goes into emergency mode of constant operation.
How to check the thermostat with a multimeter?
To check the mechanical thermostat, it must be removed. When cold (can be put in the freezer for 15 minutes), the contacts should be closed (resistance close to 0). When heated in the hands, they should open (resistance is infinity). If the circuit does not break, the part is faulty.
It is also worth mentioning the defrost sensor. If it is faulty, the evaporator becomes overgrown with a “fur coat”, which blocks the circulation of cold air. The refrigerator cannot cool the chamber to the required temperature and hums non-stop.
Freon leak and blockage in the cooling system
The most unpleasant technical reason is a refrigerant (freon) leak. This can happen due to corrosion of the evaporator tubes (especially if you cleaned the chamber with sharp objects or ice) or microcracks in the soldered joints. When freon becomes low, the pressure in the system drops, and the compressor works non-stop, trying to pump up the required pressure, but cannot turn off because the temperature does not reach normal.
The second option is Clogged capillary tube. Oil breakdown products or moisture entering the system form a plug. Freon does not circulate through the circuit, the cooling capacity drops to zero, although the motor hums very loudly and intensely. In such cases, a characteristic gurgling sound is often heard.
| Symptom | Probable cause | Necessary actions |
|---|---|---|
| The compressor is hot, cold no | Freon leak | Looking for leaks, vacuuming, refilling |
| Loud hum, gurgling | Capillary clogged | Purge system, replacement filter-drier |
| The refrigerator turns off, but does not freeze | Compressor malfunction | Replacement of the compressor motor |
| Frost only at the entrance to the evaporator | Partial leak | Circuit diagnostics, soldering |
To eliminate these problems, you need to call a technician with professional equipment: a leak detector, a vacuum pump and scales for refilling freon. It is almost impossible to eliminate a leak or blockage on your own without special tools.
Improper operation and external factors
Often the owners themselves create conditions under which the Bosch refrigerator cannot turn off. The most common but common reason is installing the unit too close to heat sources. If the refrigerator is located next to a radiator, stove, or in direct sunlight, heat exchange is disrupted. The motor has to work twice as hard to remove heat from the condenser.
It is also critical to maintain clearances for ventilation. The side walls and back must have free air access. If the refrigerator is built into a kitchen niche without proper ventilation, it will overheat and work without interruption. This leads to rapid wear of the insulation of the motor windings.
Another factor is loading with warm products. If you put a pot of hot soup or just defrosted food at room temperature into the chamber, the sensors will detect a sharp jump in heat. The compressor will operate at maximum for several hours until the temperature balance is restored. This is normal mode, but it should not last for days.
- ☀️ Do not install the refrigerator in direct sunlight.
- 🍲 Do not place food hotter than room temperature in the chamber.
- 💨 Provide a gap of at least 5-7 cm from the walls and furniture.
- 🧊 Do not open the door often and for a long time in hot weather.
Malfunction of the compressor and start relay
If all previous reasons are excluded, the problem may lie in the very “heart” of the refrigerator - the compressor. Over time, the mechanical part wears out, the valves lose their tightness, and the engine loses its power. It seems to work, but does not create enough pressure to effectively circulate the freon. As a result, the temperature does not drop and shutdown does not occur.
Often the culprit of continuous operation is starting relay. This device starts the motor. If the relay contacts are burnt or stuck in the closed position, current continues to flow to the windings even when the thermostat requires stopping. This can be visually determined by black deposits on the relay body or a characteristic crackling sound when trying to start.
In Bosch inverter models the situation is more complicated. There, an electronic board is responsible for the operation of the motor. If one of the transistors or capacitors on the inverter board burns out, the control is lost and the compressor may work chaotically or constantly. Diagnostics requires measuring the voltage at the output of the board.
⚠️ Attention: When replacing a compressor or relay, be sure to use parts with the same characteristics as the original. Installing an unsuitable relay can lead to the burnout of the windings of a new motor in a matter of minutes.
Replacing a compressor is an expensive and complex repair that requires resoldering the tubes and evacuating the system. It is often more economically feasible to consider purchasing new equipment if the refrigerator is more than 10 years old.
Electronics errors and software failures
Modern refrigerators Bosch are complex computerized systems. Sometimes the reason lies not in the hardware, but in a software or control module failure. A power surge in the network could damage the microcircuits, and the controller “forgot” how to correctly read sensor readings.
In such cases, a complete reset (reboot) helps. It is necessary to unplug the refrigerator for 15–20 minutes. This will allow the capacitors on the board to discharge and the controller memory to clear temporary errors. After turning on, the system will launch a test and possibly return to normal operation.
If after a reboot the situation repeats and error codes (for example, E or F with numbers) light up on the display, this is a direct path to the service center. Independent flashing of the control module at home is impossible and requires special equipment.
Frequently asked questions (FAQ)
How long can a Bosch refrigerator work without interruption after defrosting?
After complete defrosting and turning on the network, the refrigerator takes from 2 to 6 hours to return to work mode. During this time, the compressor may run continuously - this is normal. If it does not turn off for more than 10-12 hours, the ice does not subside or the heat inside is a sign of a malfunction.
Why does the refrigerator hum, but does not freeze or turn off?
This is a classic symptom of a freon leak or a blockage in the system. The compressor idles, trying to build up pressure, but the refrigerant is not circulating. You need to call a technician to diagnose the circuit and find the location of the leak or plug.
Is it possible to operate the refrigerator if it does not turn off?
For a short time - yes, to save food. But long-term operation without stopping (a day or more) will lead to overheating of the compressor windings and its combustion. The engine resource in this mode is exhausted within a few days. It is better to temporarily shift the food and start repairing.
How can you tell that it is the thermostat that is faulty and not the compressor?
If when you turn the thermostat knob to the “0” (off) position, the compressor goes silent, but when it returns to operating mode it hums again without stopping and does not cool, most likely the problem is in the cooling system (freon). If it turns off only when completely turned off, but there is already a deep minus inside, the thermostat is to blame.