The situation when the refrigerator stops turning off or, conversely, stops gaining cold, often indicates a failure. thermostat. This small device is responsible for maintaining a set temperature inside the chambers by opening and closing the electrical circuit of the compressor. Replacing this element yourself is one of the most accessible procedures in repairing household appliances, which does not require deep knowledge of electronics, but requires care.
Before you start disassembling the unit, you need to make sure that the problem lies in the relay. If the compressor hums constantly without turning off, or is silent, although it is warm inside, there is a high probability of a sensor malfunction. It is important to understand that thermal relay is a mechanical device that wears out over time, and its replacement is a standard maintenance procedure.
During the process you will encounter electrical current, so compliance with safety precautions is priority number one. Any manipulations with electrical components should be carried out only after the device has been completely disconnected from electrical networks. Do not neglect this rule, even if you are confident in your actions, since the risk of electric shock or short circuit is real.
To begin diagnostics and replacement work, you will need a minimum set of tools. Usually, a regular Phillips screwdriver, pliers and, preferably, a multimeter are enough to check the continuity of the circuit. In some refrigerator models, such as Indesit or Atlant, you may need to remove the plastic cover that is attached to the latches.
- 🔧 Phillips and flathead screwdrivers for removing covers and terminals.
- 🔌 Multimeter for checking thermostat contacts.
- 🧤 Dielectric gloves for additional protection.
- 📸 Smartphone for photographing the connection diagram before disassembling.
⚠️ Attention: Before starting work, be sure to defrost the refrigerator if there is ice in the chamber. Moisture can get on the electrical contacts and cause a short circuit when you first turn it on.
Diagnostics of a thermostat malfunction
The first step is to determine exactly what has gone wrong. thermostat. If the compressor runs continuously without stopping to rest, try turning the temperature control knob to the extreme “minimum” position. If the motor continues to hum and food inside the refrigerator begins to freeze, this is a sure sign of sticking relay contacts.
In the opposite situation, when the refrigerator is silent, you can carry out a simple check. With the unit connected to the network, close the contacts going to the thermostat, bypassing it. If the compressor starts, then the problem is definitely in the sensor. However, this method requires caution and an understanding of the electrical circuit to avoid damaging start relay or the motor windings.
There is also a visual inspection method that is suitable for remote tube thermostats. If the tube is damaged, freon gas could escape from it, which activated the membrane. In this case, mechanical expansion and contraction become impossible and the contacts stop switching. The integrity of the tube is a key factor in performance.
Why does the relay click?
The characteristic click when the refrigerator is operating is the sound of the contacts opening or closing inside the thermostat. If the clicks begin to occur too often or, on the contrary, disappear, and the temperature does not hold, it means that the mechanism is worn out or the tightness of the bellows tube is broken.
Connection diagram and contact marking
Having dealt with the diagnostics, we move on to the most important stage - studying the connection diagram. On the body of any thermal relay there are contact markings that indicate their purpose. Standard markings usually include numbers 3, 4 and 6, although they may differ in different models.
Contact 3 most often is the phase input from the mains or from the compressor starting relay. Contacts 4 i 6 are the output contacts that go to the compressor and, in some circuits, to the light bulb or fan. Understanding this logic is necessary for the correct installation of a new element.
| Marking | Purpose | Wire color (typical) |
|---|---|---|
| 3 | Power input (Phase) | Red / Brown |
| 4 | Compressor output | Black / Green |
| 6 | Lamp/fan output | Orange / White |
| L | Ground (case) | Yellow-green |
It is important to note that the color coding of the wires does not always meet the standards, especially if the refrigerator has been repaired previously. Therefore, you cannot rely only on the color of the insulation. Always check the circuit diagram, which is often pasted on the inner wall of the refrigerator or is in the technical data sheet.
⚠️ Attention: In some models of No Frost refrigerators, the thermostat contacts may be normally closed or normally open. Installing the wrong type of relay will lead to incorrect operation of the defrost system or compressor.
Step-by-step instructions for replacing the relay
The replacement process begins with dismantling the old device. In most refrigerators, the thermostat is located inside the refrigerator compartment, often hidden behind a plastic panel or directly on the temperature control knob. Carefully remove the handle and unscrew the mounting screws.
After gaining access to the thermostat housing, disconnect the electrical terminals. Here it is extremely important to photograph the location of the wires before disconnecting them. This action will save you from assembly errors. Then carefully pull the capillary tube out of its seat, being careful not to damage it or bend it.
☑️ Algorithm for replacing the thermostat
Installing a new one thermostat is done in the reverse order. Insert the sensitive tube into the same hole from which the old one was removed, ensuring the immersion depth matches the original. Secure the device body with screws and connect the wires strictly according to the photograph or diagram taken earlier.
After connecting all contacts, check the reliability of the terminals. They should fit tightly, without play. If the terminals are oxidized, they can be carefully cleaned with fine sandpaper or a file, but it is better to use new terminal clamps if they come with the relay.
Connection features in different models
The design and location of the thermal relay can vary significantly depending on the manufacturer and year of manufacture of the equipment. For example, in refrigerators Biryusa i Atlant mechanical relays with a long tube are often used, which is attached to the evaporator with special clamps.
In modern models LG or Samsung with a system No Frost the thermostat can be electronic or have a shortened tube built into the wall. In such cases, replacement may require partial disassembly of the inner lining of the chamber, which complicates the task.
Two-chamber refrigerators deserve special attention, where the thermostat controls only one chamber (usually the refrigerator), and the freezer operates in constant mode or is controlled by a separate sensor. Incorrectly connecting a relay from a single-chamber unit to a two-chamber unit can upset the temperature balance.
- 🧊 In models with a “crying” evaporator, the tube is attached to the rear wall.
- ❄️ In No Frost systems, the sensor is often built into the air duct.
- ⚙️ Electronic thermostats require adjustment via the control panel.
⚠️ Attention: The design of refrigerators is constantly being improved. The location of components and the type of sensors used in your model may differ from those described in the general instructions. Always check the technical documentation of the specific device.
Checking performance after installation
After completing the installation and assembly of all panels, the moment of truth comes - the first turn on. Connect the refrigerator to the mains and set the temperature regulator to the middle position. After a few minutes, you should hear a characteristic click and the compressor starts.
If the compressor starts, let the unit run until the first automatic shutdown. This can take from 20 minutes to an hour, depending on the initial temperature inside the chambers and the ambient temperature in the room. The operating time before the first shutdown is an important diagnostic parameter.
Check the door for tightness and the absence of extraneous noise. If the refrigerator turned off and after a while turned on again on its own, maintaining the cold, it means replacement of the thermostat it was successful. The regulation system has been restored.
Typical connection errors
One of the most common errors is incorrect connection of wires to contacts. By mixing up the input and output, you can cause a short circuit or leave the refrigerator without temperature control. That is why a photograph before disassembly is not just advice, but a necessity.
Another common mistake is damage to the capillary tube during installation. The thin copper tube is easily pinched or bursts if not handled carefully. If you hear a hissing sound or see traces of oil where the tube is bent, it means the seal is broken and the relay will have to be replaced again.
Also, newbies often forget to ground the thermostat housing if the old model had a grounding contact. This may cause potential to develop on the metal parts of the refrigerator, which is dangerous for the user. Always check the presence and integrity of the ground wire.
Ignoring contact cleaning can also negate all efforts. If the terminals on the wires are oxidized or melted, the new relay will quickly fail or become unstable. Cleaning the contacts or replacing the terminals is a mandatory step in a quality repair.
Is it possible to install a thermostat with other parameters?
Theoretically, it is possible if the dimensions and type of fastening match, but this is risky. Different thermostats have different response temperature ranges (differentials). Installing the wrong relay will result in food either freezing or spoiling due to insufficient refrigeration.
Why does a new thermostat click immediately after turning on?
If the click is instantaneous and the compressor does not start, the relay contacts may be stuck open or the wires are connected incorrectly. Also, the reason may be in the compressor itself or the start relay, and not in the thermostat.
Do you need to wait after replacement before turning it on?
Special waiting, as during transportation, is not required if you did not tilt the compressor. However, it is recommended to let the refrigerator stand for 10-15 minutes after installation so that the refrigerant in the system (if the tube affected the circuit) calms down, although this is not critical for the thermostat itself.