The situation when in a two-chamber refrigerator Bosch The freezer continues to diligently freeze food, and in the refrigerator compartment the temperature rises to room temperature, this is one of the most common breakdown scenarios. Owners are often frightened, believing that the unit has completely failed, but this is not always the case. Partial loss of cooling capacity indicates that the refrigerant circulation or temperature control system is functioning, but not fully.
Modern models of the German brand, be then classic NoFrost or simpler systems LowFrostequipped with complex electronics and mechanical components. When you encounter the fact that the temperature in the refrigerator compartment is above +10°C, while in the freezer it is below -18°C, this narrows the scope of troubleshooting to a few specific nodes. Ignoring the problem in the first hours can lead to spoilage of food, but there is no need to panic ahead of time.
In this article we will analyze in detail the mechanical and electronic causes of temperature imbalance. You will learn how to carry out initial diagnostics on your own and in which cases calling a specialist with professional equipment will be the only right decision. Understanding the principles of operation combined cooling system will help you make the right decision on repairs.
System leakage and refrigerant leak
One of the most likely reasons why a refrigerator Bosch the upper chamber stops cooling when the freezer is running, there is a partial leak of refrigerant. In dual-circuit systems or systems with one evaporator and air distribution, a decrease in the amount of freon leads to the fact that there is not enough of it for the full cooling cycle of both compartments. First, the cold stops flowing to a lower priority zone - the refrigeration compartment.
If there is a leak, the compressor can work almost without interruption, trying to reach the set temperature, but to no avail. If you notice that the motor-compressor is constantly humming, and the radiator grille at the back is only partially or unevenly hot, this is a sure sign lack of refrigerant. It is difficult to visually detect the location of the leak, since freon is colorless and odorless, and the tubes are often hidden in thermal insulation.
Leaks often occur in soldering areas or in foamed parts of the housing, where corrosion could form over time. If the system is completely depressurized, the compressor may run idle, overheat and eventually fail. Therefore, long-term operation of the unit with signs of leakage is strictly not recommended.
⚠️ Attention: Independent refilling of the refrigerator with freon is impossible without special equipment and skills. An attempt to simply “add” gas without finding and eliminating the leak will lead to a repeated breakdown in a short time.
To fix this problem, you need to call a specialist who will pressurize the system with nitrogen, find the location of the leak, seal it and charge the unit with new refrigerant in strict accordance with the standards for your model. Bosch.
Faulty temperature sensors and thermostat
Refrigerator electronics Bosch relies on the readings of temperature sensors to control the operation of the compressor and fans. If the sensor located in the refrigerator compartment fails and transmits incorrect data (for example, it shows that it is too cold), the module may not turn on the compressor or shut off the cold air supply. This is a classic “false rest” situation.
In models with mechanical control, the thermostat is responsible for this process. Its capillary tube may lose sensation or become dislodged. As a result, even if the chamber is warm, the contacts do not close and the cooling cycle does not start. Malfunction of the thermostat Often manifested by a sudden stop in the operation of the unit or, conversely, by its endless cyclic on-off switching.
Temperature sensors (thermistors) are semiconductor elements whose resistance changes depending on heat. Over time, their characteristics may “float”. You can check them with a multimeter, measuring the resistance at different temperatures and comparing the readings with a table of values for a specific series. Bosch.
How to check a sensor with a multimeter?
To check, you need to disconnect the refrigerator from the network, find the sensor (usually a plastic cylinder on the chamber wall), disconnect the chip and ring it. At room temperature, the resistance should be in a certain range (usually several kOhms), and when placed in the freezer it should change. If the readings do not change or show an open/short circuit, the sensor is faulty.
Replacing the sensor or thermostat is a relatively inexpensive and quick procedure. However, it is important to use original spare parts or high-quality analogues, since incorrect characteristics of a new element can lead to incorrect operation of the entire system in the future.
Problems with the NoFrost system and ventilation
In refrigerators Bosch with the system NoFrost cold is generated in the freezer compartment and is forced by a fan into the refrigeration compartment through special air ducts. If the freezer is freezing, but the top is warm, the problem often lies in poor air circulation. The fan may stop due to motor failure or freezing of the blades.
Another common scenario is blockage of air channels with ice. This occurs if the evaporator defrost system is not working correctly. The defrost heating element, timer or defrost sensor may fail, resulting in a “fur coat” growing on the evaporator in the freezer, which blocks the air supply channels. The fan hums, but the air simply does not pass through.
Symptoms of such a malfunction are often:
- ❄️ Severe freezing of the back wall in the freezer.
- 🔇 Absence of the characteristic noise of a working fan (or vice versa, the cracking of ice on blades).
- 💧 The appearance of puddles of water under the drawers or on the floor near the refrigerator (the water does not have time to drain into the drain).
To diagnose, you need to defrost the refrigerator completely (for 24 hours) and check whether cold appears in the upper chamber after turning it on. If yes, then the problem is definitely in the defrost or ventilation system. If not, the reason is deeper.
☑️ Primary diagnostics NoFrost
Failures in the operation of the compressor and start relay
The compressor is the heart of the refrigerator. In two-chamber models Bosch one compressor is often used, which pumps freon through both circuits (or one circuit with separation). If the compressor has lost its performance (valve wear), the freon pressure may only be enough to maintain low temperatures in the freezer, but it is no longer enough to cool a large volume of the refrigeration chamber.
The compressor start-up relay also often fails. It is responsible for starting the engine and protecting against overloads. If the relay is stuck or burnt out, the compressor may hum, click but not start, or start and immediately stall. In some cases, a faulty relay may pass current, but not provide the correct operating mode, which leads to inefficient cooling.
Signs of problems with the compressor group:
- 🔊 Loud knocking, clicking or buzzing when trying to start.
- 🔥 Extreme heating of the housing compressor (impossible to touch with your hand).
- ⚡ Frequent power outages or knocked out plugs (less often).
Diagnostics of the compressor requires measuring the current strength and discharge pressure. If the compressor is “weak”, replacing it is the only way out, since this unit, as a rule, cannot be repaired.
⚠️ Attention: Replacing a compressor is a complex technical procedure that requires evacuation of the system and precise dosage of oil and freon. Do not try to change the compressor yourself without experience.
Malfunctions of the control module and electrics
Modern refrigerators Bosch are controlled by an electronic module. This “brain” receives signals from sensors and controls actuators: compressor, fan, heating elements. If the triac on the control board controls the defrost heating element, or the transistor responsible for the flow switching valve, the refrigerator will stop working correctly.
A frequent problem is oxidation of the contacts in the connectors or a break in the wiring running from the door to the housing (where the sensors are located). Constantly opening and closing the door leads to broken wires in the corrugation. In this case, the module may “think” that the sensor is indicating normal, although in fact there is no connection with it.
To diagnose the control module, it is often necessary to connect diagnostic equipment or conduct deep circuit testing. Visually, burnt tracks, swollen capacitors, or traces of burning may be visible on the board. However, the absence of external signs does not guarantee the serviceability of the electronics.
Diagnostic table of main symptoms
For convenience, we will systematize the main symptoms and probable causes in a summary table. This will help you quickly navigate the nature of the breakdown of your unit Bosch.
| Symptom | Probable cause | Nature of the breakdown | Difficulty of repair |
|---|---|---|---|
| Freezer works, the top is warm, the compressor is silent | Malfunction of the thermostat or sensor | Electrics/Electronics | Low |
| The compressor is humming, does not turn off, there is not enough cold | Freon leak | Mechanics/Tightness | Average |
| There is ice in the freezer, the fan is noisy, it’s warm at the top | Faulty defrost system (NoFrost) | Mechanical/Electrical | Average |
| The compressor is hot, clicks, does not start | Start relay or the compressor itself | Electrical/Mechanical | High |
| The refrigerator turns on and off immediately | Control module or relay | Electronics | High |
What you can do yourself before calling a technician
Before filing a repair request, it is worth performing a number of simple steps that will eliminate false alarms. Sometimes the problem lies not in a breakdown, but in improper operation or external factors. Checking these points can save you time and money.
First of all, make sure that the refrigerator is not overloaded with food that is blocking the vents. Check the tightness of the sealing rubber on the refrigerator door. If the rubber comes off or becomes dirty, the cold will go away and the unit will not be able to maintain the temperature, even if it is in good working order.
It is also worth checking the temperature settings. Perhaps one of the household members accidentally switched the mode to “Eco” or minimum cooling, or activated the “Super Freeze” mode only for the freezer, which in some models can affect the distribution of compressor resources.
FAQ: Frequently asked questions
Is it possible to continue to operate the refrigerator if it is warm in the upper chamber?
For a short time - yes, to save food by moving it to another place. But you cannot keep the refrigerator in this mode for a long time. The compressor will work hard, trying to reach an unattainable temperature, which will lead to overheating and other damage. In addition, bacteria will quickly multiply in a warm chamber.
How long do you need to wait for the cold after defrosting a Bosch refrigerator?
After complete defrosting (24 hours) and turning on, the refrigerator takes from 2 to 5 hours to return to operating mode. At this time, you should not load it with products. If after 5-6 hours the temperature in the refrigerator compartment has not dropped below +10°C, it means that defrosting did not help and repairs are required.
Why is the back wall in the refrigerator compartment covered with ice?
This may indicate a malfunction of the defrost sensor (in NoFrost systems) or that the door does not close tightly, and humid air constantly gets inside, condensing on the cold wall. This also happens when there is a freon leak, when the compressor operating cycle is disrupted.
Is it necessary to change the freon completely when eliminating the leak?
Yes, when repairing the tightness system, the old freon is released, the system is evacuated to remove moisture and air, and then a new portion of refrigerant is charged strictly according to the weight specified in the technical documentation for your model Bosch.