A decrease in the efficiency of the refrigeration chamber or, conversely, excessive freezing of products often indicates incorrect operation of the thermoregulation system. In most cases, the culprit of such problems is thermostat, which stops sending the correct signals to the compressor. Replacing this element requires attention to detail, since the quality of the connection determines the further safety of the products and the service life of the motor.
The replacement process does not always require calling a technician if you have basic skills in working with electrical equipment and tools. However, before starting work, you must clearly understand the structure of your unit, since mechanical and electronic regulators have fundamental differences in installation. In this article we will look at the key stages of dismantling the old sensor and installing a new one.
Safety is the first thing you need to take care of. Any manipulations with the electrical wiring are carried out only after the device is completely disconnected from the network. Never try to close the thermostat contacts to check the operation of the compressor without load, this can lead to failure of the start relay. The correct approach to diagnostics and installation will avoid costly repairs in the future.
Principle work and types of thermostats
A thermostat is a device that monitors the temperature inside the chambers and opens or closes the electrical power supply circuit of the compressor. In older models, most often found mechanical thermostatsworking on the basis of the expansion of gas or liquid in a sensitive tube. When the temperature reaches a set value, the pressure in the tube changes and the contacts open, stopping the motor.
Modern refrigerators, such as Liebherr or Boschare often equipped with electronic sensors. They transmit data to the control board, which already makes the decision to turn on the compressor. Despite the difference in design, they have the same goal - maintaining a stable temperature regime. An error in determining the type of sensor can lead to the purchase of an incompatible spare part.
- 🔧 Mechanical models have a long capillary tube that is attached to the evaporator.
- 💻 Electronic analogues are a compact element with wires that do not have moving mechanical parts.
- ⚙️ Hybrid systems can combine mechanical damper control and electronic temperature reading.
⚠️ Attention: An attempt to install a mechanical thermostat instead of an electronic one (or vice versa) without altering the control circuit will lead to incorrect operation of the unit or complete system failure.
Understanding your device type is critical. If your refrigerator previously had a regulator with a rotary knob and clicks when switching modes, we are talking about mechanics. If the temperature setting is done through a digital display, then there is electronic sensorinstalled inside, the connection principle of which is distinguished by the absence of physical contacts for opening the compressor circuit by the sensor itself.
Diagnostics and preparation for replacement
Before disassembling the refrigerator, you need to make sure that the problem lies exactly in the thermostat. Users often confuse a sensor malfunction with problems start relay or a freon leak. If the compressor does not start at all, but is humming or clicking, it is worth checking the thermostat circuit. For mechanical models, there is a simple diagnostic method - closing the contacts.
To carry out the test, you will need to remove the thermostat casing. In refrigerators like Atlant or Indesit it is often located inside the chamber or outside, at the back of the unit. After providing access to the contacts, you need to carefully remove the wires and connect them together (excluding the ground wire, if any). If the motor starts and starts working continuously, it means that the thermostat is faulty and requires replacement.
☑️ Diagnostics before replacement
It is also important to inspect capillary tube. If it shows signs of corrosion, kinks or damage, then even a new thermostat may not work correctly due to loss of tightness of the sensing element system. In such cases, the tube must be positioned in the same way as the old one so that the length of immersion in the evaporator corresponds to the factory parameters.
⚠️ Attention: When working with mechanical thermostats, avoid sharp bends in the capillary tube. Damage to thin copper will lead to a leak of filler gas, and the device will have to be thrown away.
Removing the old thermostat
The process of removing the old device begins with completely de-energizing the refrigerator. This is a mandatory safety rule and, if ignored, may result in electric shock. After disconnecting, you need to gain access to the mounting location. In models with a drip defrosting system, such as Samsung or LG old series, the thermostat is often hidden under a plastic panel inside the refrigerator compartment.
Carefully disconnect the wires from the contacts. Before doing this, it is strongly recommended to photograph the connection diagram or sketch the colors of the wires and their location. In some models, the wires may be soldered, then they will have to be cut, leaving a reserve for connection to a new device. Remember that color marking wires may differ depending on the manufacturer, so you cannot rely only on color.
The next step is to remove the sensitive tube. It can be fixed in a special hole in the evaporator or pressed with a bar. Pull it out smoothly, without jerking, so as not to damage the channel in the refrigerator body. If the tube is covered with electrical tape or clamps, they must first be removed.
The table below shows the locations of thermostats in popular brands:
| Refrigerator brand | Thermostat location | Access type | Mounting features |
|---|---|---|---|
| Atlant | Inside the chamber, top right | Removing the lamp shade | The tube is fixed in the channel |
| Indesit | Outside, at the back, near the compressor | Removing the rear cover | Fixing with screws to the body |
| Beko | Inside, under the top cover | Removing the top panel | The tube is inserted into evaporator |
| Stinol | Inside, left or right | Removing the decorative trim | Rigid mounting of the body |
What to do if the tube is stuck?
If the capillary tube frozen to the evaporator, do not try to pull it out by force. Wait until the refrigerator is completely defrosted (at least 10-12 hours) so that the ice melts and the tube is released naturally.
Installation and connection diagram of the new sensor
Installation of the new thermostat is carried out in the reverse order of dismantling. First, the sensing tube is installed. It must be immersed in the same hole from which the old one was removed, to the same depth. Typically, the immersion depth is from 25 to 40 mm, but it is better to focus on the marks or the length of the old tube. Insufficient immersion will lead to frequent switching on of the compressor, and excessive immersion will lead to its infrequent operation and an increase in the temperature in the chamber.
Next comes the electrical connection. If you didn't take a photo of the circuit, use the universal rule for most mechanical thermostats: the wires coming from the mains and from the compressor are connected to contacts that close when the temperature drops. The ground wire (usually yellow-green) is connected to the thermostat body or a special terminal, if provided by the design.
For electronic models, the connection is even simpler: they use keyed connectors that cannot be inserted incorrectly. However, it is important to ensure that contacts clean and not oxidized. If necessary, use a spray to clean the contacts.
- 🔌 Connect the wires according to the color markings or the diagram made earlier.
- 🔩 Securely fasten the thermostat housing with screws to avoid vibration.
- ❄️ Make sure that the tube does not touch the moving parts of the fan (in No Frost systems).
After connecting all the wires, check the reliability of the connections. Pull the wires lightly - they should not jump out of the terminals. If twisting was used, be sure to insulate it with heat shrink or high-quality electrical tape to avoid short circuits in conditions of high humidity.
Setup and initial start-up
After installing the new thermostat, the refrigerator is ready for the first start. However, there is no need to rush to plug it into the network right away. Allow the device to stand upright for at least 2-3 hours, especially if it may have tilted during transportation. This is necessary to stabilize the oil in the compressor.
When you turn it on for the first time, set the regulator knob to the middle position (usually the number 3 or the “Normal” mark). Do not immediately set the maximum cold, this will create an extra load on the system. During the first few hours of operation, carefully monitor the cycle: the compressor should turn on, cool the chamber to the set temperature and turn off.
If the compressor runs continuously for more than 2 hours and does not turn off, the thermostat may not sense the desired temperature. This may be due to incorrect installation of the tube or a defective new part. In this case, you need to turn off the appliance again and check the installation.
⚠️ Attention: If you hear a loud click and a burning smell immediately after turning on, immediately unplug the refrigerator. There was probably an error in the wiring diagram.
To accurately adjust the temperature inside the chamber, it is recommended to use a separate thermometer. Place it in a glass of water on the middle shelf and leave it overnight. The readings must correspond to the set values on the regulator. If the temperature is very different, calibration may be required, if the design of the thermostat allows it (the presence of an adjusting screw under the seal).
Frequent installation errors
The most common mistake is ignoring the tightness of the hole through which the capillary tube passes. If this hole is not sealed with mounting foam or a special sealant, warm air from the room will constantly enter the chamber. This will lead to the formation of ice on the evaporator and increased load on the compressor.
Another mistake is incorrect placement of the tube. Some craftsmen simply place it on the evaporator without fixing it. Over time, the vibration moves the tube and it no longer reads the temperature correctly. Use standard clamps or aluminum tape for fixation.
Confusion with ground wires is also common. If you connect the ground wire to the compressor control contact, the refrigerator body may become energized, which is dangerous. Always check the integrity of the insulation and the correct connection.
In conclusion, replacing a thermostat is a completely solvable task for a DIYer, but it requires care and compliance with safety precautions. If you doubt your abilities or are faced with a non-standard connection diagram, it is better to turn to professionals.
Is it possible to use a thermostat from another refrigerator?
The use of analogues is possible, but only if the technical characteristics match: temperature range, capillary tube length, type of fastening and location of contacts. There are no universal solutions, since different manufacturers (for example Danfoss, Thermo, K50) may have different response parameters.
Why does the new thermostat click but does not turn on?
This may indicate a malfunction of the compressor start relay or the motor itself. It is also possible that the contacts of the new thermostat do not close completely due to defects or incorrect adjustment. Check for voltage at the thermostat output when the refrigerator is plugged in.
How often should you change the thermostat?
The service life of a mechanical thermostat is on average 5-7 years. Electronic sensors last longer, but can fail due to power surges. Planned replacement is not required, only when a malfunction occurs.
Is the gas inside the capillary tube dangerous?
There is an inert gas or refrigerant in small quantities inside the tube. If the tube is damaged, the gas quickly evaporates and does not pose a serious danger to humans in a well-ventilated area, but you should not specifically inhale it.