The situation when your Bosch refrigerator ceases to maintain a low temperature in the upper compartment always arises suddenly and causes a lot of inconvenience. Products begin to deteriorate and an unpleasant odor appears inside, which requires immediate attention. Most often, owners are faced with the fact that the freezer continues to work properly, while the refrigerator compartment turns into a regular storage shelf.
There can be many reasons for this behavior of the equipment: from the banal sticking of the thermostat to serious damage to the cooling circuit or failure of the compressor. Fault diagnosis requires careful attention to detail and understanding of the operating principles of your specific model Bosch. In this article, we will analyze in detail the main failure scenarios and methods for eliminating them.
It is important to understand that modern units are equipped with complex electronics that can block the compressor from starting at the slightest suspicion of a failure. If you notice that the equipment is humming, but there is no cold, or, on the contrary, there is absolute silence, do not rush to call a technician. An initial analysis of the situation often allows you to save time and money by identifying simple operating errors.
Operating errors and simple causes
Before disassembling the equipment or looking for spare parts, it is necessary to exclude trivial factors. Users often forget that fast freezing mode (SuperFrost) left on for a long time can cause the evaporator in the refrigerator compartment to freeze, blocking air circulation. In systems NoFrost this is a critical moment, since the ice plug blocks the cold supply channels.
Check the position of the temperature regulator. If you accidentally move the knob or touchpad to the minimum cooling mode, the camera will no longer freeze properly. It is also worth paying attention to the tightness of the products against the back wall. If vegetables or packages are placed close to the rear panel, they block the outlet of cold air and can cause local freezing of the sensors.
Pay special attention to the door. A door that is not tightly closed is one of the most common causes of failures. Seal could become dirty, deformed, or simply worn out over time. If the door is not sealed, warm, moist air constantly enters the chamber, which condenses and freezes, disrupting the operation of the system.
- ❄️ Check whether the "Super Freeze" or "Vacation" mode is turned on.
- 🚪 Make sure the door closes tightly and not skewed.
- 🥦 Move the food away from the back wall by at least 3-5 centimeters.
- 🧹 Clean the rubber seal from grease and crumbs with warm water.
⚠️ Attention: If you place the refrigerator close to the wall or furniture, the heat exchange of the condenser is disrupted. This can lead to overheating of the compressor and temporary stoppage of the refrigerator compartment.
Problems with the NoFrost system and defrosting
Refrigerators Bosch with the system NoFrost are most susceptible to problems with defrost. In these models, cold is forced into the upper chamber by a fan through special channels from the freezer. If the defrost system fails, the evaporator becomes overgrown with a “coat” of ice, the fan stops spinning or simply cannot drive air through the ice monolith.
The key elements here are the defrost heating element, the defrost thermostat (or sensor) and the fuse. If one of these components fails, the defrost cycle will not start or will be interrupted. As a result, after several days or even weeks of operation in this mode, the refrigerator compartment stops cooling food, although the compressor can work continuously.
Diagnostics often require full defrosting technicians within 24 hours. If after this the refrigerator begins to freeze normally, but after 5-7 days the problem returns with the same force, it means that the fault lies in the defrost unit. The electronics detect an abnormal situation and can block the operation of the compressor to avoid its breakdown.
Symptoms of a defrosting heating element malfunction
If the heating element is burnt out, the ice on the evaporator does not melt. This can be checked with a multimeter for an open circuit. The resistance of a working heating element is usually from 200 to 400 Ohms. If the device shows one or infinity, the part requires replacement.
Often the culprit is a defrost timer or a control module that simply “forgets” to turn on the heating. In models with electronic control Bosch this may be accompanied by flashing temperature indicators on the panel.
- 🧊 Ice crust on the back wall of the refrigerator compartment.
- 🔇 The fan does not make noise (blocked by ice or burned out).
- 📉 The temperature in the chamber is above +10...+15 degrees.
- 💡 The indicators on the panel blink or show an error.
☑️ Diagnostics of the NoFrost system
Faults compressor and start relay
The heart of any refrigerator is compressor. If it doesn't start, there won't be any cold anywhere. However, a situation where only the refrigerator compartment does not work, even if the freezer is working, more often indicates problems with refrigerant circulation or cold distribution, rather than complete death of the motor. However, a decrease in compressor performance (wear of valves) can lead to the fact that the freon pressure is only enough for the freezer.
A frequent cause of startup failure is starting relay. This is a small device that provides an impulse to start the engine. If the relay is stuck or burnt out, you may hear a characteristic click every few minutes: an attempt to start, a click, and silence. The compressor may be hot at this moment, which indicates its overheating due to unsuccessful start attempts.
In two-compressor models Bosch (which is less common, but happens in large series), each compartment is responsible for its own motor. If you have just such a model, then the lack of cold in the upper compartment while the freezer is running directly indicates a malfunction of the upper compressor or its control circuit.
| Symptom | Probable cause | Sound character |
|---|---|---|
| Silence, light yes | Faulty electronics or thermostat | Absent |
| Clicks every 2-5 minutes | Start relay burnt out | Short hum and click |
| Humming continuously, no cold | Freon leak or blockage | Smooth hum |
| Humming, but weakly | Compressor wear (valves) | Quiet, uneven hum |
⚠️ Attention: If the compressor is hot to the touch and smells of burnt insulation, immediately unplug the device. Further operation may lead to a fire or complete failure of the unit.
Refrigerant leakage and system blockage
One of the most unpleasant technical problems is freon leak. The refrigerant circulates in a closed circuit, and if a microcrack appears in the tubes (often due to corrosion or mechanical damage during cleaning), the gas gradually evaporates. First, the performance drops, the compressor begins to work non-stop, trying to gain temperature, and then the cold ceases to be enough even for the freezer, or it remains only there.
The second option for a hydraulic problem is clogging of the capillary tube. An ice or mud clot may have formed in the system. This prevents the normal flow of freon. In such cases, the refrigerator may work in cycles: freezing for a while, then stopping, then starting again, but the efficiency will be extremely low.
It is difficult to diagnose a leak visually, since freon is colorless and odorless. However, an oily spot can sometimes (not always) be seen at the gas outlet, as freon circulates along with the compressor oil. It is impossible to fix such a malfunction on your own without a vacuum pump and a refill kit.
In models with a foamed evaporator (when the tubes are mounted into the walls of the housing), leakage often occurs in the foamed circuit. This is a complex case, requiring either the installation of an external evaporator ("crying" on the back wall inside the chamber), or a complex opening of the case, which is not economically feasible.
Failures in the operation of electronics and sensors
Modern refrigerators Bosch are controlled by complex electronic modules. If the main control unit receives incorrect data from temperature sensors, it may not give a command to turn on the compressor or fan. Sensors (thermistors) change their resistance over time and begin to “lie” to the controller.
For example, if the sensor in the refrigerator compartment shows that it is already -5 degrees there (although in fact +15), the control module will consider the task completed and turn off the cooling. Sensors are checked by measuring their resistance at different temperatures and comparing them with a table of ratings for a specific model.
It is also worth mentioning software failures. Sometimes electronics can freeze. In such cases, it helps resetting errors or completely reboot the device by disconnecting from the network for 15-20 minutes. This clears temporary errors in the controller's memory.
- 🔌 Unplug the device for 20 minutes to reboot.
- 📟 Check the error code on the display (if any).
- ⚡ Inspect the control board for swollen capacitors.
- 🌡️ Test the temperature sensors with a multimeter.
⚠️ Attention: Models Bosch with the HomeConnect or Wi-Fi system may require a firmware update. Outdated software sometimes causes conflicts in the operation of sensors. Check the software version in the official application or on the manufacturer's website.
Mechanical damage and wear of seals
In addition to electronics and freon, the problem may lie in the physical condition of the camera. Rubber seal the door loses over time elasticity, cracking or coming away from the fabric. Warm air is constantly sucked in through the resulting cracks. The compressor tries to compensate for heat loss, working for wear, but at some point its power ceases to be enough.
You can check the tightness using a simple sheet of paper method. Clamp the sheet with the door around the perimeter. If it pulls out without effort or falls out easily, the seal is broken. It is also worth checking the door hinges: if they are loose, the door warps and does not fit tightly even with the seal intact.
Mechanical damage can also occur inside: cracks in plastic panels, broken air duct dampers. In systems NoFrost the damper regulates the amount of cold air coming from the freezer. If it is stuck in the closed position or the drive is torn off, the cold simply does not reach the food.
Frequently asked questions (FAQ)
Why does the Bosch refrigerator hum, but does not freeze in the upper chamber?
Most likely, there was a failure in the system defrost (the evaporator is frozen) or there is a freon leak. The compressor works, trying to gain temperature, but there is not enough cooling capacity. Diagnostics by a technician is required.
How to defrost a Bosch refrigerator correctly?
You must unplug the appliance, remove all food and leave the doors open for at least 24 hours. Do not use a hairdryer or hot water to speed up the process so as not to damage the plastic and evaporator tubes.
What does a flashing temperature indicator mean?
Flashing usually indicates that the permissible temperature in the chamber has been exceeded or a sensor malfunction. If after defrosting and rebooting the indicator continues to blink, repair is required.
Is it possible to replace the door seal yourself?
Yes, this is possible. The new seal needs to be heated (with a hairdryer or hot water) so that it becomes elastic, and carefully inserted into the groove around the perimeter of the door, following the instructions for your model.
Why does ice freeze on the back wall in the Bosch refrigerator?
This is a sign of a malfunction of the defrost system (heating element, sensor, timer) or problems with the door seal. Moisture enters the chamber and freezes on the coldest surface. Repair of the defrost unit is required.