The situation when the refrigerator stops turning off or, conversely, does not want to gain cold, most often indicates a failure of the temperature sensor. It is thermostat responsible for opening the compressor power circuit when the specified parameters are reached. Replacing this unit yourself is a procedure accessible to a person with basic tool handling skills, but it requires strict adherence to safety precautions and sequence of actions.
Before starting work, you need to understand that you are dealing with electric current and refrigerant. Incorrect installation can lead to a short circuit or even depressurization of the circuit if the capillary tube is touched. In this article we will look in detail at how to properly disinfect seat, connect a new regulator and configure its operation for different brands of equipment.
It is important to immediately note that the design of refrigeration units from different manufacturers may differ significantly. Somewhere the sensor is hidden under a plastic cover, and somewhere access to it is possible only after dismantling the internal panel. The capillary tube of the thermostat is extremely sensitive to mechanical damage and kinks, therefore, all manipulations require accuracy and attention to detail.
Fault diagnosis and selection spare parts
Before buying a new part, you should make sure that the problem lies in the thermostat. If the compressor hums continuously and a “coat” of ice forms in the chamber, or the motor is silent and the food begins to deteriorate, these are classic symptoms. However, similar symptoms may appear if there is a freon leak or a faulty start relay. For accurate diagnostics, a multimeter is often required, which “rings” the contacts of the device in different temperature conditions.
Selecting a suitable spare part is a critical stage. Thermostats differ in length capillary tube, type of fastening, presence of a third contact group and direction of shaft rotation. Installing the wrong model can lead to incorrect operation of the refrigerator: it will either undercool the food or work non-stop, consuming excess electricity.
- 🔍 Look for the markings on the body of the old part, usually it starts with K, TAM or TA.
- 📏 Measure the length of the capillary tube, including bends, since the length margin is important for proper installation.
- 🔌 Pay attention to the number of contacts: there can be two or three, depending on the control circuit.
You should not ignore the manufacturers' recommendations, especially if we are talking about modern models with electronic control, where the mechanical thermostat is replaced by a temperature sensor. In such cases electronic module requires a completely different approach and often cannot be replaced independently without special equipment.
Necessary tools and preparation for work
To successfully carry out repair work, you will need a minimum set of tools, which can be found in the arsenal of most home craftsmen. The main requirement is cleanliness of hands and tools, since moisture or dirt entering the thermostat mechanism is unacceptable. It is also important to ensure good lighting of the work area, especially if access to the unit is limited.
You will need screwdrivers (Phillips and flathead), side cutters or wire cutters, and a multimeter to test circuits. If you plan to replace the door seal after removing the panels, it is worth preparing it in advance. Do not forget about the defrosting container if there is ice left in the chamber, which may interfere with access to the fastening elements.
⚠️ Attention: All work on replacing electrical equipment must be carried out exclusively with the refrigerator disconnected from the network. Residual voltage in capacitors can be dangerous, so let the equipment stand without power for 10-15 minutes.
Preparing the work area includes clearing the space around the refrigerator. You will need access not only from the front, but also from the rear and from the top of the unit. Remove all products from the chambers in advance so that they do not interfere with manipulations and do not spoil during long-term downtime of the equipment.
☑️ Preparing to replace the thermostat
Removing the old thermostat
The process of retrieving a faulty node begins with determining its location. In most models of Atlant, Indesit or Stinol refrigerators, the thermostat is located inside the refrigerator compartment, often hidden behind a plastic cover or directly in the temperature control knob. In some cases, for example, in refrigerators Liebherr or Bosch, access can be provided through the back wall or top panel.
Carefully remove the regulator handle by pulling it towards you or unscrewing the fixing screw, if provided by the design. Next, you should remove the protective casing. Be careful with plastic latches, which become brittle in the cold and easily break if handled carelessly. After removing the panel, you will see the device itself, mounted in the chamber wall.
The next step is to disconnect the electrical wires. Before doing this, it is strongly recommended to take a photo of the connection or draw a diagram, since the colors of the wires in different models may differ. Nip off the wires with wire cutters closer to the thermostat body, leaving the “tails” of sufficient length for subsequent twisting or soldering to the new device. Remove the old thermostat by carefully pulling the capillary tube out of the process channel.
- 📸 Take a photo of connecting the wires before they are disconnected.
- ✂️ Use side cutters to avoid damaging the insulation of the remaining wires.
- 🧊 Be careful not to damage the internal plastic of the camera when removing the tube.
If the capillary tube is stuck to the evaporator wall, do not use force. Try to carefully warm the outlet of the tube with a hairdryer at a minimum temperature or defrost the chamber completely so that the ice releases the part.
Installation of a new thermostat and electrical connection
Installation of a new temperature regulator is carried out in the reverse order of dismantling. First of all, you need to insert the capillary tube into the mounting hole. The length of the new thermostat tube may differ from the original one. If it is longer, the excess is carefully rolled up into rings inside the chamber, trying not to create sharp creases with a radius of less than 30 mm. In short, make sure that the sensitive element reaches the temperature control zone.
The thermostat housing is secured to the refrigerator wall using standard screws or latches. It is important to ensure a tight fit of the housing, if provided for by the design, for correct heat transfer from the internal volume of the chamber to the sensing element. After fixing the mechanical part, they move on to the electrical part.
The connection of the wires can be made by twisting followed by insulation by heat shrink or, more reliably, by soldering. If the new thermostat has different terminals than the old ones, use adapters or carefully strip the ends of the wires. The main thing is to ensure reliable contact, since significant starting currents of the compressor pass through these circuits.
What to do if the colors of the wires do not match?
The color marking of the wires is not always standardized. Focus on the connection diagram: the phase usually goes to the thermostat input and from the output to the compressor, and the ground (if any) is connected separately. Use a multimeter in continuity mode to find a circuit that opens when the thermostat housing heats up in your hands.
Check the reliability of all connections. Wires should not touch moving parts of the fan (if there is one) or sharp metal edges. Lay out the wiring harnesses so that they do not interfere with the closing of the panels and are not pinched by them.
Connection diagrams and contact correspondence table
Understanding the principle of operation of the electrical circuit of the refrigerator is necessary for proper installation. The thermostat in the circuit acts as a switch that opens the compressor power circuit when a low temperature is reached. In some circuits there is a third contact, which is responsible for turning on the operation indicator lamp or defrost alarm.
Below is a table showing typical contact assignments for the most common series of thermostats. However, always check the technical documentation for the specific model of your refrigerator, as manufacturers may make changes to the design.
| Thermostat type | Pin 1 (Input) | Pin 2 (Compressor Output) | Pin 3 (Additional) |
|---|---|---|---|
| Two-contact (K-50, TAM-112) | Phase (L) | To the compressor | Absent |
| Three-contact (K-59, TAM-133) | Phase (L) | To the compressor | To the lamp/signal |
| With defrost button | Phase (L) | To the compressor | Defrost circuit |
| Imported (Danfoss) | Line (L) | Load (Compressor) | Defrost/Light |
When connecting three-pin models, it is important not mix up the contacts, otherwise the refrigerator may not turn on or, conversely, may not turn off. If you are not sure of the correctness of your actions, it is better to use the services of a professional technician, since a mistake can cost a burnt out compressor.
Adjusting and setting the temperature mode
After installing a new thermostat, it is necessary to configure it. Factory settings may not suit your kitchen environment or storage requirements for specific foods. Adjustment is carried out using a screw located on the thermostat body, or by turning the temperature control knob.
For precise adjustments, it is recommended to use an external thermometer placed in a glass of water in the center of the chamber. By rotating the adjusting screw (usually marked with a dot or numbers), ensure that the contacts open at a temperature of +3...+5°C for the refrigerator compartment. For the freezer, the parameters will differ depending on the freezing class.
- 🌡️ Let the refrigerator operate for several hours before making final adjustments.
- 🔧 Turn the adjusting screw in small steps (no more than half a turn).
- ⏱️ Between each when adjusting, pause to stabilize the temperature background.
Do not forget that setting the temperature too low leads to increased energy consumption and a reduction in the life of the compressor. Too high a temperature can cause bacteria to grow and food to spoil. The optimal operating mode strikes a balance between energy efficiency and food preservation.
⚠️ Attention: If, after replacing the thermostat, the refrigerator begins to operate cyclically (turns on and off too often), the sensitivity may be set incorrectly or the capillary tube is not immersed deep enough in the control zone. Check the tight fit of the tube to the evaporator.
Frequent errors and checking the result
The final stage of work is checking the functionality of the assembled system. Plug in the refrigerator and listen to the compressor work. It should start within a few seconds of being turned on. After some time, when the temperature in the chamber reaches the set value, the compressor should turn off with a characteristic click.
One of the common mistakes is poor insulation of twisted wires. In conditions of high humidity inside the refrigerator (especially during the defrosting period), moisture can cause oxidation of the contacts or a short circuit. Use high-quality insulating materials and check the tightness of the connections.
The error of incorrect positioning of the capillary tube is also common. If it does not fit tightly against the evaporator or is in an area where the temperature does not reflect the actual condition in the chamber, the thermostat will not work correctly. Make sure that the tube is secured with standard clamps or adhesive tape.
If after all the manipulations the problem is not solved, perhaps the fault lies deeper: in the compressor itself, the defrost system or the electronic board management. In this case, self-repair may be ineffective, and professional diagnostics will be required.
Is it possible to install a thermostat with a different marking?
Installation of an analogue is possible if the basic parameters match: capillary tube length, temperature range, type of fastening and number of contacts. However, it is better to look for an original spare part or a proven analogue recommended by the manufacturer to avoid problems with setup.
Why does the refrigerator not turn off after replacing the thermostat?
There may be several reasons: the thermostat is incorrectly configured, the capillary tube does not fit tightly to the evaporator, there is a freon leak, or the new thermostat itself is faulty. It is also worth checking the integrity of the door seal.
Do you need to defrost the refrigerator before replacing?
Yes, complete defrosting is required. This is necessary to safely dismantle the panels, prevent moisture from getting on the electrical contacts and make it easier to remove the capillary tube, which may be frozen in ice.
How to check the serviceability of a new thermostat before installation?
Use a multimeter in dial mode. At room temperature the contacts should “ring” (be closed). If you put the sensitive bulb of the thermostat in the cold (for example, in the freezer or blow cold air), the contacts should open and the device will stop beeping.