Sudden increase in temperature in refrigerator compartment or, conversely, excessive freezing of food often indicates a failure of the climate control sensor. In models Bosch this unit is responsible for the timely switching on and off of the compressor, maintaining the specified microclimate. If you notice that the unit works without interruptions or starts up too rarely, and a “coat” of ice forms on the back wall, most likely the thermostat needs to be replaced.
Performing this procedure yourself allows you to save a significant amount that service centers charge for calling a technician and diagnostics. However, the process requires accuracy, a basic set of tools and strict adherence to safety precautions when working with electrical appliances. In this article, we will analyze in detail the algorithm of actions necessary for the successful repair of your equipment.
Diagnostics of a thermostat malfunction
Before disassembling the refrigerator, you need to make sure that the problem lies in the thermostat, and not in a freon leak or a compressor malfunction. The primary sign of a breakdown is a violation of the temperature regime: food in the refrigerator compartment begins to deteriorate, although the compressor hums continuously. In other cases, the unit may be silent for days, leading to the defrosting of the contents.
For an accurate check, you can use the exclusion method. If, when the thermostat contacts are forcibly closed, the compressor starts and cools normally, then the motor is working. It is also worth paying attention to capillary tube: if it is damaged or disconnected from the evaporator, the sensor will not read the correct temperature readings.
There is a simple way to check with a multimeter, which requires removing the part. At room temperature the contacts should “ring” (show resistance), and when placed in the cold (about -15°C) they should open. If the circuit does not break in the cold or does not close in the heat, thermostat is considered faulty and requires replacement.
⚠️ Attention: Before starting any diagnostic work, be sure to disconnect the refrigerator from the electrical network to avoid electric shock!
Necessary tools and preparation
To successfully carry out repair work, you will need a minimum set of tools that can be found in the arsenal of most home craftsmen. The main tool will be Phillips screwdriver of the appropriate size, since fasteners in refrigerators Bosch most often have just such a slot. You may also need a flat-head screwdriver to carefully remove the plastic latches.
It is important to prepare a container to collect melt water if defrosting the chamber is required during the dismantling process. It would be a good idea to have a multimeter on hand for a final check of the functionality of the new part before final assembly. All work should be carried out in good lighting so as not to damage the fragile plastic elements of the interior.
- 🔧 Phillips and flathead screwdrivers
- 🔋 Multimeter for checking the circuit
- 🧤 Protective gloves (optional)
- 🧊 Water container and rag
- 🔦 Flashlight for illuminating internal cavities
Access to the thermostat in different models
The location of the thermostat in refrigerators Bosch may differ depending on the series and year of manufacture of the device. In classic mechanically controlled models, the sensor is often hidden under a plastic cover inside the refrigerator compartment, next to the temperature control knob. In more modern modifications, access may require removing the top cover of the unit or dismantling the lampshade.
If the adjustment knob is located inside the chamber, you must carefully remove it by pulling it towards you, and then unscrew the screws securing the thermostat housing. In some cases, it is necessary to remove the top panel of the refrigerator by unscrewing the bolts on the back and sides to gain access to the assembly from above. Always act without excessive force to avoid breaking the plastic guides.
Particular attention should be paid to models with a system No Frostwhere the thermostat can be located in a niche behind the rear wall or in the control unit. Here it is important not to damage the thermal insulation and carefully remove the capillary tube, which can be glued to the evaporator.
| Model type Bosch | Thermostat location | Difficulty of access |
|---|---|---|
| Classic (KGN, KGV) | Inside the chamber, under the handle | Low |
| With top panel | Under the top cover of the unit | Medium |
| Built-in series | Behind the decorative door panel | High |
| No Frost | Near the evaporator or in the control unit | Medium/High |
Step-by-step instructions for dismantling
The process of removing the old thermostat begins with completely disconnecting the device from the network and, if necessary, defrosting it for 10-12 hours. After removing the decorative overlays and gaining access to the assembly, it is necessary to fix the exact position capillary tube. It can be secured with special clamps or glued, and its position is critical for the correct operation of the new sensor.
Carefully disconnect the electrical wires from the contact group of the thermostat. It is best to mark each wire with a marker or take a photo so that when installing a new part you do not mix up the terminals. Then carefully remove the thermostat housing from the seat, trying not to damage the surrounding elements.
☑️ Removal algorithm
If the capillary tube is glued to the evaporator, it must not be torn off by force. You must wait until it is completely defrosted or use a hair dryer on low power (with great care) to soften the glue. Damage to the tube will lead to a refrigerant leak and will require expensive repairs from professionals.
⚠️ Attention: The capillary tube is very thin and can be easily bitten. Do not use wire cutters or scissors in close proximity to it.
Installing a new thermostat and setting
Installing a new one thermostat is done in the reverse order of dismantling. It is important to choose an analogue with identical parameters, especially the length of the capillary tube and the temperature range of operation. If the tube of the new sensor is longer, it can be carefully rolled into a ring and secured in free space, but under no circumstances should it be bent or shortened.
After fixing the housing and connecting the wires according to the previously made marks, check the reliability of the connections. The capillary tube must be placed in the same position as the old sensor, pressed tightly against the surface of the evaporator or placed in a sleeve, if the design provides for this. The accuracy of the refrigerator’s operation depends on the quality of contact between the tube and the cooled element.
After completing installation, assemble all the removed panels and turn on the refrigerator. The initial startup may take some time until the system is up and running. Do not load the chamber with products immediately; let the unit reach idle temperature for 2-3 hours.
Common mistakes and precautions
One of the most common mistakes is ignoring the condition of the door seals after repair. If during work you often opened the door or removed panels, check the tightness of the rubber band. A loose closure will cause the compressor to run continuously, giving the false impression that the newly installed thermostat is faulty.
Also, technicians often forget to check the tension of the contacts inside the terminal block. Poor contact will lead to sparking, heating and eventual melting of the plastic, which can cause a fire. Use a multimeter to check the reliability of the connection before final assembly.
- ❌ Using an unsuitable thermostat analogue
- ❌ Kink in the capillary tube during installation
- ❌ Weak contact in the electrical circuit
- ❌ Ignoring checking the door seals
⚠️ Attention: If after replacing the thermostat the refrigerator continues to work incorrectly, the problem may be deeper (freon leakage, compressor malfunction) and require professional diagnostics.
How to extend the life of a new thermostat?
For maximum durability of the new unit try not to open the refrigerator door unless necessary, especially during the hot season. Sudden temperature changes cause the thermostat to operate more often, increasing contact wear. Also, keep the condenser at the back of the unit clean - overheating of the system negatively affects all components.
Questions and answers (FAQ)
Is it possible to install a thermostat from another manufacturer, for example, Danfoss or K59?
Yes, this is often possible if the mounting dimensions and length match capillary tube and temperature range. However, it is better to look for original spare parts Bosch or proven analogues specified in the technical documentation for your model.
Why does the refrigerator freeze too much even after replacing the thermostat?
This may indicate incorrect installation of the capillary tube (poor contact with the evaporator) or that a thermostat with the wrong one is selected temperature range. Also check the door tightness.
Is it necessary to defrost the refrigerator before replacing?
It is advisable, especially if the capillary tube is glued to the evaporator with ice. An attempt to tear it off by force will damage the thin tube and leak freon.
How long does a new thermostat last?
The service life of a high-quality thermostat is on average 5-7 years, but depends on the intensity of use and the stability of the voltage in the network.