Breakage thermostat is one of the most common reasons for which the refrigerator stops freezing or, conversely, turns food into ice blocks. Owners of household appliances who decide to repair them themselves often encounter difficulties when installing a new temperature controller. The main difficulty lies not in the electrical connection, where everything is quite simple, but in the mechanical installation of the sensitive element.
It is the capillary tube thermostat that requires special attention, since it is responsible for reading the temperature inside the chamber. If it is secured incorrectly, too deep or, conversely, not deep enough, the sensor will not work correctly. This will lead to the compressor turning on too often or rarely, which will significantly reduce the life of the motor and spoil the products.
In this article we will look in detail at where exactly the tube should be attached, what nuances exist for different models of refrigerators and how to avoid common mistakes. Understanding the operating principle of this unit will help you carry out a quality replacement and forget about the problem for a long time.
The principle of operation and the role of the capillary tube
The temperature regulator is a mechanical or electronic device that controls the operation of the compressor. A mechanical thermostat is based on a sealed system filled gas freon or with a special liquid. This system consists of the regulator body itself and a thin copper tube, which is called a capillary.
The essence of the work is simple: when the temperature in the fridge compartment changes, the pressure inside the tube changes. When it gets warmer, the gas expands, the pressure rises, and the membrane opens the contacts, starting the compressor. When cooling, the process occurs in the reverse order. Therefore, physical contact of the tube with the cooled object is critical for the accuracy of the readings.
If the tube does not fit tightly to the surface of the evaporator or a special plate, heat transfer will be disrupted. The sensor will “think” that the chamber is warmer or colder than it actually is. This leads to the so-called “short cycle” of the motor operation or, conversely, to its constant operation without shutting down.
⚠️ Attention: The capillary tube is very thin and fragile. If carelessly bent or bent at an acute angle, it may burst, which will lead to leakage of filler gas and complete inoperability of the thermostat.
Modern models can use electronic sensors, but in classic refrigerators Indesit, Atlant, Beko and Stinol mechanical thermostats with capillary water are still widely used tube. Understanding their structure is the key to successful repair.
Types of fastening depending on the design of the refrigerator
The answer to the question of where the tube is attached directly depends on the type of your refrigerator. There are two main options for the design of an evaporation system, and in each case the installation is carried out differently. You can’t make a mistake here, since the mounting location determines the accuracy of thermoregulation.
Old models and many budget options use open evaporator. This is an aluminum plate with zigzag tubes located directly in the freezer compartment. In such refrigerators (often “Saratov”, “Biryusa” or old ones) the thermostat tube is attached directly to this evaporator. Indesit) The thermostat tube is attached directly to this evaporator.
In more modern models where the system is used No Frost or “crying” the evaporator is hidden behind a plastic panel; mounting is carried out differently. Here the tube is inserted into a special technological hole in the chamber body or fixed on a metal heat sink strip, which, in turn, is attached to the back wall.
You can determine the type of fastening by looking into the freezer. If you see an aluminum grill without a plastic coating, you have the first option. If the back wall is smooth, plastic, and it’s just cold from the air, you have the second option, and the tube needs to be pushed deep into the hole.
Installation of the tube in refrigerators with an open evaporator
Let's consider the first, most common mounting option. In a freezer, there is often a special tab, bracket, or clamping bar on the evaporator (aluminum plate). It is under this that the capillary tube should be placed capillary tube.
Sometimes there is no standard fastening, and the tube is simply glued or pressed with a clamp. The main rule here is to ensure maximum contact area. The tube should run along one of the evaporator tubes or fit tightly to its surface in an area where a thick crust of ice does not form that interferes with heat transfer.
☑️ Checking the tube fastening
It is important not to overtighten the fastening element. Aluminum is a soft metal and excessive force can damage the evaporator housing, causing refrigerant to leak from the refrigerator circuit. This is a much more serious and expensive breakdown than replacing the thermostat.
The tip of the tube must be free. It should not rest against the back wall of the camera or other metal elements that could transmit vibration. Vibration from a running compressor can be transmitted to the tube, causing false alarms or, conversely, sticking of contacts.
Installation in models with a hidden evaporator (No Frost)
In refrigerators with a system No Frost or a hidden evaporator, you will not see an aluminum grill. In such models, on the back wall of the refrigerator compartment (less often the freezer) there is a small round hole with a diameter of about 5-7 mm. This is where the sensitive element is immersed.
When replacing the thermostat in such models, for example, LG, Samsung or Electrolux, the tube is carefully inserted into this hole. Immersion depth is critical. Usually it ranges from 25 to 35 mm, but it is better to look at the exact data in the technical documentation for the specific model.
If the tube is inserted too deeply, it may rest against the heat insulator or damage the internal partitions. If it is too shallow, the sensor will respond to the temperature of the air in the chamber, and not to the temperature of the evaporator, which will lead to incorrect operation.
What to do if the tube is loose in the hole?
If the diameter of the hole is larger than the diameter of the tube, you can use a small rubber bushing or a drop of heat-resistant sealant (very carefully!) to fix the position and improve heat sink However, it is better to choose a thermostat with a tube of a suitable diameter.
Often, such holes already have a factory plug or heat-conducting paste. When installing a new tube, it is advisable to add a little silicone grease or special heat-conducting paste to the tip of the tube before insertion. This will improve the transfer of heat from the walls of the hole to the sensor.
Table of correspondence between depth and type of fastening
To systematize the information, consider the main installation parameters depending on the brand and type of refrigerator. The data is average, since manufacturers can make changes to the design.
| Refrigerator type | Mounting location | Immersion depth / Features | Examples of brands |
|---|---|---|---|
| With open evaporator | Aluminum freezer plate | Tight contact along the length of 5-10 cm | Atlant, Indesit (old), Biryusa |
| Hidden evaporator | Hole in the rear wall | 25-35 mm, heat-conducting lubricant required | LG, Samsung, Bosch, Siemens |
| Two-chamber No Frost | Hole in the chamber or on the evaporator | Up to 40 mm, bend control | Electrolux, Beko, Haier |
| Industrial cabinets | Special pocket or clamp | Depends on the model, often reinforced fasteners | Pozis, Liebherr (professional series) |
As can be seen from the table, the approach to installation varies significantly. In industrial models, the requirements for fastening reliability are even higher due to intensive use.
⚠️ Attention: The design and location of the holes may vary depending on the year of manufacture of the model. Before starting work, check the service documentation or diagram of a specific device.
Common installation errors and their consequences
The most common mistake is bending the tube at an angle of less than 90 degrees or the formation of “creases”. Copper is a ductile material, but if sharply bent it will crack. Even a microscopic crack will lead to the release of gas, and the thermostat will stop responding to temperature changes.
The second mistake is insufficient contact. If the tube is just lying next to the evaporator, but is not pressed down, the refrigerator will not work properly. The compressor may turn on too late, when the food has already begun to deteriorate, or too early, consuming excess electricity.
The third mistake is damage to the insulation of the wires going to the thermostat. In the process of pushing the tube into narrow holes, the sharp edge of the plastic can touch the wires. This may cause a short circuit to the refrigerator body.
It is also worth mentioning the mistake of ignoring cleanliness. If you are replacing the thermostat in an old refrigerator, there may be dirt, ice, or old grease left in the hole. They must be removed, otherwise the sensor will heat up from friction or work with a large error.
Checking the correct installation and configuration
After the tube is installed and secured, it is necessary to check the operation of the system. Don't rush to load products right away. Turn on the refrigerator and let it run idle for at least 2-3 hours.
Watch the cycle of operation. The compressor should turn on, cool the chamber to the set temperature and turn off. If the refrigerator runs non-stop or turns on too often (every 2-3 minutes), it means that the tube is installed incorrectly or the wrong thermostat is selected.
You can use an external thermometer to fine-tune the temperature inside the chamber. Place it on the middle shelf, set the control to the middle position and check the readings after a few hours. The temperature must correspond to the set mode (usually +3...+5°C for the refrigeration chamber).
If you notice that a “coat” of ice forms on the evaporator unevenly or, conversely, the evaporator is dry with the engine running, try to slightly change the position of the tube (if the design allows) or check the pressure.
Frequently asked questions (FAQ)
Is it possible to lengthen the capillary tube of the thermostat?
It is strictly not recommended to extend the tube by welding or soldering at home. This will break the tightness of the system filled with gas under pressure. It is better to buy a thermostat with a tube of the required length or carefully lay the excess in a ring inside the case without bending it.
How to lubricate the tube before installing it in the hole?
It is best to use a special heat-conducting paste for electronics or silicone grease. You should not use ordinary machine oil or grease, as they can thicken in the cold or destroy plastic elements.
What to do if the tip of the tube rests and does not go further?
Do not use excessive force. Try to slightly rotate the tube around its axis. If it hits an obstacle inside the wall, the thermostat model may not be the right length, or there is a defect inside. It is dangerous to force it in - you can break the internal partition of the chamber.
How to understand that the thermostat tube is broken?
If during bending or installation you hear the hissing of escaping gas, it means that the seal is broken. This thermostat will not work. Also, a sign of a malfunction may be a complete lack of reaction of the contacts to heating or cooling of the thermostat bulb.