Modern refrigeration units of the brand Bosch famous for their reliability and sophisticated electronics, which carefully controls the microclimate inside the chambers. However, even the most advanced equipment can fail, and often the cause of malfunction is a malfunction in the sensor system. Temperature sensor This is a small but critical element that tells the control module when to turn the compressor on or off.
If you notice that the food in the refrigerator has begun to freeze or, conversely, deteriorate due to insufficient cold, the problem may lie precisely in incorrect readings of the temperature sensor. Owners often wonder where this element is physically located and whether they can reach it themselves. The location depends on the specific series of the refrigerator and the type of defrosting system.
In this article we will analyze in detail the architecture of refrigerators Boschso that you can accurately determine the location of the sensor in your model. Understanding the structure of the unit will help you save time on diagnostics or even carry out repairs without calling a technician.
The principle of operation of the Bosch thermoregulation system
The temperature maintenance system in refrigerators Bosch is built on a constant cycle of reading data and reacting to it. Thermal sensor (or a thermostat in more older models) acts as the “eyes” of the system, continuously measuring the thermal state of the air or evaporator. The received data is transmitted to the electronic control module, which makes a decision to start or stop the compressor.
Modern models with the system No Frost use not one, but several sensors. One is responsible for the temperature in the main chamber, the other in the freezer compartment, and often the third controls the defrosting process of the evaporator. Such a distributed network allows you to maintain high cooling accuracy and save energy.
⚠️ Attention: Electronic sensors are very sensitive to voltage surges. If the lights in your house flicker frequently, it is recommended to use a stabilizer to protect the control board and sensors from burning.
Failure of any of the elements of this chain leads to desynchronization of the refrigerator. The compressor may work continuously, trying to reach a non-existent low temperature, or, conversely, turn on too rarely. Diagnostics It begins with checking the readings of these sensors.
Types of sensors and their features in different models
Before looking for where sensor, you need to understand what type is installed in your refrigerator Bosch. Depending on the year of manufacture and series, the manufacturer uses different design solutions for climate control.
Mechanical is often found in older models. thermostat. This is a device with a capillary tube that is filled with a temperature-sensitive gas. When heat changes, gas expands or contracts, opening or closing electrical contacts. Such sensors usually have an adjustment knob inside the chamber.
Modern units are equipped with electronic ones NTC thermistors. They are compact elements whose resistance varies depending on temperature. These sensors have no moving parts and are highly accurate, but require proper electronics to process the signal.
You can determine the type of sensor visually or by indirect signs. If you have a digital control panel that displays precise degrees, chances are there are electronic thermistors inside. If the adjustment occurs by turning the scale from 1 to 7, you are dealing with mechanics.
Where the sensor is located in the refrigerator compartment
The search for the sensor in the main compartment depends on how the cooling system is implemented. In most models Bosch with a system No Frost or Low Frost, the air sensor is often hidden from the user's eyes so as not to disturb the aesthetics and not interfere with the placement of products.
Most often, the main temperature sensor of the refrigerator compartment is located in the upper part of the internal space. It can be built into the plastic panel of the chamber ceiling or located behind the decorative grille of the air circulation system. In some models of the series VarioFresh the sensor is hidden in a special compartment next to the vegetable storage area.
If your model has a mechanical thermostat, its capillary tube usually runs along the inner wall, and the contact block itself is located outside, on the back wall of the case, or hidden under a plastic cover inside. You can get to it by carefully removing the protective cover.
Is it possible to move the sensor?
It is strictly not recommended to move the standard location of the sensor. Changing the installation location will lead to incorrect readings, since in different areas of the chamber the temperature may differ by several degrees.
To access the electronic sensor in modern models, partial disassembly of the internal plastic is often required. Mounts usually made with latches that need to be pressed with a plastic spatula so as not to damage the fragile material.
Sensor location in the freezer and No Frost zone
The freezer is a zone of extreme temperatures, so sensors here play a key role in preventing the formation of an ice coat. In systems No Frost it is critical to know exactly the moment when the evaporator is frozen in order to start the defrost mode.
The defrost sensor in the freezer Bosch is most often located directly on the aluminum evaporator. To see it, you need to remove the back wall of the freezer compartment. The sensor is usually fixed in a special hole or pressed to the metal with a bracket to ensure tight contact.
A separate air temperature sensor in the freezer can be located at the top of the chamber or integrated into the air damper unit. It is he who gives a signal when the temperature set by the user is reached, for example, -18°C.
☑️ Search for the sensor in the freezer
When searching, pay attention to the wires going to the plastic panel. They often lead directly to where the thermistor is installed. Be careful: plastic becomes very fragile after prolonged exposure to cold and can crack if handled carelessly.
Table of sensor locations in popular Bosch series
Different series of refrigerators have their own design features. Below is a summary of information that will help you navigate depending on your model.
| Refrigerator series | Location of the refrigerator compartment sensor | Location of the freezer compartment sensor | Sensor type |
|---|---|---|---|
| Bosch Serie 4 | Behind the top panel or in the ventilation unit | On the evaporator (behind the rear wall) | Electronic NTC |
| Bosch KGN (No Frost) | In the ceiling of the chamber, under the decorative grille | Built into the defrost system evaporator | Electronic NTC |
| Bosch KGV (Low Frost) | On the side wall inside or outside at the back | Capillary tube around the perimeter | Mechanical/Hybrid |
| Bosch Intra | Hidden in the top parts, access through removing the shade | Behind the rear panel of the freezer | Electronic NTC |
This table is for reference only, as the manufacturer may make changes to the design without notice. If your model is not listed, be guided by the general search principles described above.
Symptoms of malfunction and diagnostic methods
Understand what temperature sensor out of order, based on characteristic symptoms. The refrigerator ceases to “understand” what is happening inside the chambers and begins to behave chaotically. Ignoring these signs can lead to food spoilage and compressor failure.
Main symptoms of malfunction:
- ❄️ The compressor runs non-stop, and the temperature in the chamber does not drop below +10°C.
- 🧊 Food in the refrigerator compartment freezes, although the regulator is set to minimum.
- 💡 An error appears on the display (for example, E1 or E2) or the temperature indicator flashes.
- 🔊 The motor turns on and off too often (short cycle).
For accurate diagnostics you need a multimeter. The sensor is removed from the socket and its resistance is measured. At room temperature, a working NTC thermistor Bosch usually shows a resistance in the range 5-7 kOhm. When cooling (for example, if you hold it in your hand or put it in the freezer), the resistance should gradually increase.
⚠️ Attention: If the resistance of the sensor shows zero (short circuit) or infinity (open), the element must be replaced. Attempts to “fix” it by insulating or heating are useless.
The process of replacing the sensor with your own hands
If diagnostics have confirmed a breakdown, the sensor can be replaced yourself. This is a procedure of medium complexity, requiring a minimum set of tools: a screwdriver, a multimeter and a new compatible sensor.
The first step should always be to completely disconnect the refrigerator from the power supply. Working with live electrical appliances is deadly. After this, empty the chambers of food and remove the shelves to gain access to the back wall or ceiling.
Carefully remove the plastic panels hiding the sensor. Disconnect the wiring connector (usually located on the top of the chassis or behind the control panel). Install the new sensor in the same position as the old one, ensuring tight contact with the surface, if required by the design.
After assembly, turn on the refrigerator and check its operation for several hours. The temperature should stabilize within the specified limits. If the error on the display disappears and the operating mode becomes normal, the repair can be considered successful.
Which sensor most often fails in Bosch?
Statistics from service centers show that the defrost sensor in the freezer compartment most often breaks down. It operates in an aggressive environment (water, ice, temperature changes), which leads to oxidation of the contacts or destruction of the thermistor housing.
Is it possible to temporarily operate a refrigerator without a sensor?
Theoretically, you can short-circuit the circuit to make the refrigerator work, but this will lead to continuous operation of the compressor and deep freezing of all products. Long-term operation in this mode will quickly damage the main unit.
Where to buy an original sensor for Bosch?
Original spare parts have specific part numbers (for example, starting with 00.. or 64..). It is better to look for the exact model number (E-Nr) indicated on the nameplate inside the camera. Universal Chinese analogues often have a different resistance curve and will not work correctly.
Why does the refrigerator not freeze after replacing the sensor?
Perhaps the new sensor has a different resistance or you connected the wires incorrectly. Also, the problem may not be in the sensor, but in the control module, which does not process the signal, or in the absence of freon in the system.