A sudden stop of the compressor or, conversely, its continuous operation often indicates a malfunction. thermostat. This small device is responsible for maintaining a set temperature inside the chambers, opening and closing the electrical circuit at the right time. If you notice that the food in the refrigerator has begun to freeze or, on the contrary, deteriorate due to lack of cold, the first thing you should check is this particular unit.
Independent repair of a thermostat is a task quite feasible for a person with basic skills in working with tools, but it requires compliance with safety precautions and an understanding of the principles of operation of the device. Touch control panels Modern models can hide mechanical damage to the sensor, so it is important to carry out proper diagnostics before replacement. In this article, we will look at how to identify a breakdown, what tools are needed and how to properly install a new regulator.
Before starting disassembly, make sure that the unit is completely disconnected from the power supply. Even briefly touching exposed live wires can lead to serious consequences. Next, we will look at a step-by-step algorithm of actions that will help you bring the refrigerator back to life without calling a technician.
Operating principle and types of thermostats
The main task of the thermostat is to control the temperature of the evaporator. Structurally, most of these devices are a sealed capsule filled heat-sensitive agent (gas or liquid), which responds to temperature changes by expansion or contraction. This process is transmitted to a membrane, which mechanically opens or closes the contacts, controlling the compressor.
There are two main types of devices found in household appliances: mechanical and electronic. Mechanical models, such as Tam 112 or K 59are widespread in refrigerators of older generations (Atlant, Indesit, Stinol). They are reliable, cheap and easy to diagnose with a multimeter. Electronic thermostats are complex microcircuits with resistance sensors and require more in-depth knowledge to test.
It is important to understand that the length of the capillary tube for mechanical thermostats can vary. When replacing, it is necessary to select an analogue with similar parameters, otherwise the refrigerator will not work correctly: either it will not turn off at all, or it will work with long interruptions. The exact marking on the body of the old thermostat is the only reliable guide when buying a spare part.
- 🔍 Mechanical: they are controlled by turning the knob, have a capillary tube, and are easily dialed by a tester.
- 💻 Electronic: transmit a signal to the control board, often combined with a display, require resistance testing.
- ⚙️ Universal: some models (for example, TAM-133) have a removable capillary tube, which simplifies replacement in hard-to-reach areas places.
⚠️ Attention: Installing a thermostat with a shorter capillary tube than the original will result in the sensor not having time to respond to temperature changes, which will cause frequent starts of the compressor.
Fault symptoms and primary diagnostics
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 most striking sign of a thermostat failure is the absence of a characteristic click when turning the regulator to its extreme positions. If the compressor is silent and the light inside is on, this often indicates an open circuit in the sensor.
Another common symptom is “endless” operation of the motor. The refrigerator hums for days without turning off, the food in the upper chamber turns into ice. This indicates that the contacts of the thermostat are “stuck” in the closed state, and the signal to stop the compressor is not received. In such cases, even forced defrosting does not help for long.
For the initial check, you can use the exclusion method. Try closing the thermostat contacts directly (more on this in the section on replacement). If after this procedure the compressor starts working, then the problem is definitely in the sensor. If the motor does not start even with the contacts closed, look for the reason in the start relay or the compressor itself.
- ❄️ Lack of cold: the compressor does not turn on, it is warm in the chamber, there are no clicks.
- 🧊 Severe freezing: the refrigerator works without stopping, a formation forms on the back wall “fur coat.”
- 🔌 Short cycles: the motor turns on for 1-2 minutes and immediately turns off (rare, but possible with incorrect calibration).
It is also worth paying attention to the condition of the capillary tube. If it is damaged, the gas has escaped and the device stops responding to temperature. A visual inspection of the tube for kinks and creases can answer the question about the cause of the breakdown.
Necessary tools and workplace preparation
Refrigerator repair requires not only theoretical knowledge, but also the right tools. You don't need a complex industrial kit, but a basic DIY kit is a must. First of all, prepare a multimeter (tester) to check the electrical circuit - without it, the diagnosis will be blind.
To disassemble the case and remove the panels, you will need different types of screwdrivers: Phillips (PH1, PH2) and flat. Some models, such as Liebherr or Boschmay use Torx screws, so it's best to have a set of bits on hand. Pliers are also useful for carefully removing the terminals.
Organize good lighting. The insides of a refrigerator, especially the evaporator area, are often hidden deep within the cabinet, and dim light can lead to errors when disconnecting wires. Prepare a container for small parts so as not to lose screws during operation.
☑️ Preparation for repair
- 🔧 Tools: set of screwdrivers, pliers, side cutters (for wire cutters), multimeter.
- 🧼 Consumables: isopropyl alcohol for cleaning contacts, insulating tape or heat shrink.
- 📦 Spare parts: new thermostat corresponding to the model of your unit.
Step-by-step instructions for replacing the thermostat
The replacement process begins with completely disconnecting the refrigerator from the network. Locate the power cord and unplug it from the outlet. Only after this can you begin to dismantle the inner lining. In most models, the thermostat is hidden under a plastic cover inside the refrigerator compartment or behind a decorative panel on the outside, next to the handle.
Carefully remove the temperature control handle. It can be removed with a simple push or have a hidden locking screw under the plug. Removing the handle will give you access to the thermostat housing mounting screws. Unscrew them and remove the control unit.
The most crucial moment is working with the capillary tube. It is very thin and fragile. It should not be bent at an acute angle, twisted or scratched with sharp objects. Damage to the tube will result in a gas leak and the new thermostat will have to be thrown away. Carefully move the old tube to the side, remembering the trajectory of its installation, and install the new one in the same grooves.
Next you need to disconnect the electrical wires. Before doing this, it is strongly recommended to photograph the connection diagram or mark the wires with a marker so as not to confuse them during assembly. Usually the terminals are simply removed by force, but in older models they can be soldered - then a soldering iron is required.
| Wire color | Designation | Function | Note |
|---|---|---|---|
| Red / Pink | L | Phase (input) | Power supplied from the mains |
| Black / Brown | 1 | Output to compressor | Closes when turned on |
| Yellow / Green | 2 | Output to lamp/fan | Opens when the compressor is running |
| Blue | Grounding | Protection | Attached to the body |
Install the new thermostat into the seat, secure it with screws and put the terminals on the contacts according to the marks made earlier. Make sure the connections are tight and not loose. After assembly, check the operation of the device by turning on the refrigerator.
What to do if the capillary tube is too long?
If the new tube is longer than the old one, it can be carefully rolled into a spiral with a diameter of at least 5 cm and placed in the free space behind the evaporator. The main thing is to avoid sharp bends and creases that will block the passage of gas.
Adjustment and performance testing
After installing a new thermostat, the refrigerator must be started and monitored for several hours. Ideally, the operating cycle should look like this: 10-15 minutes of compressor operation and 30-40 minutes of rest (the cycle may vary depending on the load and ambient temperature).
If the compressor does not turn on, check the contacts again. The terminal may have slipped or oxidized. If the engine hums but does not start, and after a few seconds the relay clicks, the problem may be with the starter, not the thermostat. However, if you are confident that the rest of the electrics are working properly, try turning the adjustment knob.
To fine-tune the temperature inside the chamber, you can use an external thermometer by placing it in a glass of water on the middle shelf. By turning the thermostat knob, achieve readings of +3...+5°C. You should not turn the knob sharply - the mechanics need time (about 15-20 minutes) to react to the change in setting.
⚠️ Attention: If, after replacing the thermostat, the refrigerator began to work “jerkily” (turns on for 1 minute, turns off for 5), perhaps the new sensor has a capillary tube that is too short or an incorrect response range. Replacement with a more suitable model is required.
Pay attention to the freezing of the evaporator. If the “fur coat” appears only in the corner where the tube lies, it means that the heat exchange is impaired. In this case, you can use a special heat-conducting paste or press the tube tightly to the evaporator with a clamp, but without fanaticism, so as not to crush it.
Typical mistakes in self-repair
The most common mistake is neglecting safety precautions. Working with electrical appliances under voltage is prohibited. Even if you think you are just “fixing the wiring,” the risk of getting an electric shock or dropping a metal object on the control board is real. Always work only with the device turned off.
The second mistake is rough handling of the capillary tube. Many beginners try to straighten it by force, pulling or bending it at a right angle. This leads to microcracks and immediate loss of functionality of the new part. Act with pinpoint precision.
The third mistake is ignoring the markings. Installing a universal thermostat “by eye” without taking into account the temperature range of operation leads to the fact that the refrigerator either does not freeze to the required temperature or freezes the food. Always look for a complete analogue by catalog number.
- 🚫 Ignoring photo fixation: Assembling “how to” often leads to extra wires.
- 🚫 Using low-quality electrical tape: in cold and humid conditions, it quickly peels off, causing a short circuit.
- 🚫 Forced starting: An attempt to start the compressor bypassing the thermostat for a long time can damage the motor.
Remember that modern refrigerators with a system No Frost have a more complex circuit where the thermostat can control not only the compressor, but also fans or defrosting heating elements. In such cases, an error in the connection can lead to failure of the entire defrosting system.
Frequently asked questions (FAQ)
Is it possible to repair an old thermostat rather than change it?
Theoretically, you can replace the bellows or bend the contacts, but in practice this inappropriate. The tightness of the capsule is broken when opened, and it is almost impossible to find spare parts for older models (such as TAM). It is easier and more reliable to buy a new analogue, which is inexpensive.
Why does the refrigerator not turn off after replacing the thermostat?
There may be several reasons: the temperature range of the new sensor is incorrectly selected, a freon leak (the compressor is working, but there is no cold, the sensor does not work) or a malfunction of the compressor itself. Also check the tight fit of the capillary tube to the evaporator.
Where is the thermostat located in Indesit and Atlant refrigerators?
In most models of these brands, the thermostat is located inside the refrigerator compartment, in the upper right corner, hidden under a plastic cover on which the temperature control knob is attached. In some older models, it may be located outside, above the door.
How to check the thermostat with a multimeter?
It is necessary to remove the terminals from the thermostat contacts. Switch the multimeter to continuity mode (or resistance measurement). At room temperature, the contacts should “ring” (resistance is close to 0). If you put the sensor in the freezer for 10-15 minutes, the circuit should break (a unit will appear on the screen or the sound will disappear).