Equipment owners who are faced with interruptions in the operation of the freezer or constant thawing of food often begin to look for the answer to the question of where the thermostat of the Pozis refrigerator is located. This small but critical element is responsible for maintaining the set temperature by turning the compressor on and off at the right moments. If your unit has stopped freezing or, conversely, has turned food into a block of ice, the problem most likely lies in this particular unit.
Understanding the design and exact location thermostat is the first step to self-repair, which will save you significant money on calling a technician. However, it is worth remembering that interfering with the electrical circuit requires caution and compliance with safety precautions. In this article, we will analyze in detail the design of the temperature control system in models Pozis, consider the symptoms of malfunctions and provide a step-by-step algorithm of actions for diagnosis and replacement.
The principle of operation and the design of the thermostat
The thermostat, or thermostat, is a mechanical or electronic device that senses the temperature inside the refrigerator compartment and signals the compressor to start or stop. In classic refrigerator models Pozis, such as the RD or Sviyagaseries, mechanical thermostats are most often used. Their work is based on a change in the volume of a gas-filled sensitive system (bellows) when heated or cooled.
When the temperature in the chamber rises above the set one, the gas in the capillary tube expands, increasing the pressure onto the bellows membrane. This mechanical action opens or closes the electrical contacts, starting the motor-compressor. Insulated tube (capillary) emerging from the regulator body is inserted directly into the evaporator or attached to it in order to accurately read changes in thermal conditions.
In more modern models with electronic control, such as Pozis RK-139 or Smart, the function of a mechanical sensor is taken over by thermistor. This is a semiconductor element whose resistance changes depending on temperature. The signal from it is sent to the electronic control module, which already makes a decision about the operation of the compressor. Replacing such elements requires not only physical replacement of the part, but often also calibration or testing of the circuit.
⚠️ Attention: Never try to repair the body of a mechanical thermostat or solder the capillary tube yourself. Violation of the tightness of the bellows makes the part completely unsuitable for use, since the working substance evaporates.
The key element of the design is the adjusting screw, which allows the user to change the tension of the spring inside the mechanism, thereby setting the temperature range. It is this screw that is connected to the adjustment knob that you see inside the refrigerator compartment. If the handle scrolls endlessly or, conversely, is jammed, this is a direct sign of mechanical destruction of the internal components.
Typical symptoms of a malfunctioning thermostat
Before disassembling the refrigerator and looking for where the thermostat is located in the model Pozis, you need to make sure that the problem lies there. The absence of cold does not always indicate a sensor failure; it could be a freon leak or a compressor malfunction. However, there are a number of specific signs that indicate failure of the thermostat. One of the most obvious symptoms is the continuous operation of the compressor without shutdowns. If the motor hums constantly, and the temperature in the chamber drops significantly below normal, turning vegetables into ice, it means that the thermostat contacts are “stuck” in a closed state and do not allow the system to go into standby mode. In this case, thermostat.
One of the most obvious symptoms is the continuous operation of the compressor without shutdowns. If the motor hums constantly, and the temperature in the chamber drops significantly below normal, turning vegetables into ice, it means that the thermostat contacts are “stuck” in a closed state and do not allow the system to go into standby mode. In this case capillary tube may be in working order, but the mechanics of the contacts are broken.
The opposite situation - the refrigerator does not turn on at all. The light inside is on, there is power, but the motor is silent. If in this case the forced closure of the thermostat contacts (which we will discuss below) starts the compressor, then the diagnosis is clear: temperature regulator requires replacement. It is also worth paying attention to the following signs:
- 🔌 Sudden temperature changes: products either freeze or thaw without changing the handle settings.
- 🧊 The appearance of a “snow coat” on the back wall even in models with No Frost, which indicates an incorrect defrost cycle due to false sensor readings.
- 🔊 Clicks and crackles inside the chamber, accompanied by a lack of response from the compressor.
- 🎛️ Visual damage: melting of the housing, burn marks on the contact group or broken adjustment knob.
It is important to differentiate the breakdown thermostat from problems with the start relay. If the compressor tries to start, makes a beep and clicks, but immediately stalls, the problem is most likely in the relay or the motor itself. If there is absolute silence or, conversely, the motor runs for days without stopping, the culprit is most likely temperature sensor.
Where is the thermostat located in Pozis refrigerators
The location of the thermostat in refrigerators Pozis depends on the year of manufacture of the model and type of control (mechanical or electronic). In most classic two-chamber models, such as RD-109, Sviyaga-405 or RD-149, the thermostat is located inside the refrigerator compartment. Traditionally, it is hidden in a plastic casing, which also serves as a lampshade for the lighting lamp.
To get to the unit, you need to open the door of the refrigerator compartment and pay attention on the right or left upper part of the internal volume. There you will see a plastic block from which the temperature control knob comes out. In Pozis models with mechanical control, the thermostat is almost always hidden under a protective plastic casing, which is secured with latches or screws. By removing this casing, you will gain access to the part itself and the wires that go to it.
In models with system No Frost or more modern electronics, the situation may differ. Here, sensors (thermal resistors) can be built directly into the chamber wall or located in the air ducts. However, if we are talking about a classic thermostat with a capillary tube, look for it at the evaporator. In some modifications, for example, in old Soviet or early Russian models, the thermostat could be placed outside, on the top of the refrigerator body, but for modern Pozisov this is rare.
To accurately determine the search location, check the table below, which shows data on popular series:
| Refrigerator model | Thermostat location | Sensor type | Access |
|---|---|---|---|
| Pozis RD-109 / Sviyaga | Inside the chamber, under the lamp shade | Mechanical (T-133, TAM-133) | Removing the plastic casing |
| Position RK-139 | Inside the chamber, top right | Electronic (thermistor) | Removing the decorative panel |
| Posis Sviyaga-405 | Inside the chamber, combined with the ceiling | Mechanical (T-133) | Unscrewing the ceiling screws |
| Pozis Biryusa (analogues) | Inside the chamber, upper left corner | Mechanical | Removing the protective box |
If you do not find the thermostat in the standard location, check the technical documentation of the specific model. Sometimes manufacturers change the layout, hiding the assembly behind decorative panels on the ceiling of the chamber. The main rule: look for the adjustment knob - the thermostat is always located directly below it or is connected to it mechanically.
Dismantling and preparation for replacement
Before you begin to physically remove the faulty part, it is necessary to ensure safe working conditions. Repair of electrical appliances requires mandatory disconnection from the network. Even if it seems to you that you are just “looking”, the risk of electric shock from accidentally touching bare 220V wires is too great.
The dismantling process begins with completely defrosting the refrigerator. Remove all food, unplug the unit and leave the doors open for at least 8-10 hours. This is necessary not only to remove ice, but also to ensure that any condensation that might get on the contacts completely evaporates. Working with wet components is prohibited.
After defrosting, remove the plastic casing hiding the thermostat. It is usually held in place by two screws or plastic clips. Be careful with plastic - in the cold it becomes brittle and can easily crack if moved carelessly. Disconnect the adjustment knob, if it is removable, by simply pulling it towards you.
- 📸 Take a photo of the wire connection diagram before disconnecting them. The colors of the wires in different batches may vary, and the photo will help to avoid errors during assembly.
- 🔧 Prepare tools: screwdrivers (Phillips and flat-head), pliers, side cutters and possibly a multimeter for checking.
- 🧤 Wear protective gloves to avoid cutting yourself on the sharp edges of the metal elements of the evaporator or housing.
Now you need to disconnect capillary tube from the evaporator. It can be secured with a special clamping bar or simply inserted into the hole. Remember or mark with a marker the depth of immersion of the tube - when installing a new thermostat, it will need to be inserted to the same depth. Do not pull the tube sharply, it is very thin and is easily pinched or broken.
⚠️ Attention: The capillary tube of the thermostat is filled with freon or other gas under pressure. It is strictly forbidden to bite, bend or pierce the tube. This can lead to the release of gas and loss of functionality of the new part even before installation.
After releasing the tube, unfasten the thermostat housing itself from the chamber wall. It can be secured with screws or latches. Disconnect the electrical wires from the contact group. If the wires are soldered, you will have to carefully remove them with a soldering iron. If terminal blocks or “chips” are used, simply remove them.
☑️ Checklist before dismantling
Instructions for installing a new thermostat
Installation of a new one thermostat is carried out in the reverse order of dismantling. However, there are important nuances here, ignoring which will lead to the fact that the refrigerator will not work or will not work correctly. First of all, make sure that you purchased the exact same model of regulator. They may differ in the length of the capillary tube, the type of contacts (normally open or normally closed) and the temperature range.
Start by installing the capillary tube. Carefully insert it into the evaporator opening to the same depth to which the old one was immersed. Secure the tube with a clamping bar or standard fasteners. Make sure that the tube does not touch moving parts (if any) and that there are no kinks. Carefully roll the excess tube into a ring and place it in the free space behind the back wall of the chamber, making sure that it does not interfere with the closing of the door.
Fix the thermostat housing in its normal place. Connect the electrical wires strictly according to the photograph or color marking taken earlier. If you use soldering, be sure to insulate the joints with heat shrink tubing or good quality electrical tape. Poor insulation can lead to a short circuit and failure of the compressor.
What to do if the length of the capillary tube is different?
If the new tube is longer, carefully roll the excess into a ring with a diameter of at least 5 cm and secure with a clamp in a warm place (outside the freezing area) to avoid false readings. In short, this is critical, such a thermostat cannot be used, since it will not reach the temperature measurement zone.
After connecting all the wires and fixing the case, reinstall the plastic casing and adjustment knob. Make sure all screws are tight and no wires are caught between the chassis and bezels. Now you can proceed to the first test run.
Plug in the refrigerator. The compressor should start working immediately after switching on. Place the control knob in the middle position. Let the unit run for several hours without loading it with food. Check whether the motor turns off when the desired temperature is reached (usually this can be heard by a characteristic click and the cessation of the hum).
Checking performance and setting
After replacement thermostat it is important to make sure that the refrigerator is in operating mode. During the first hours of operation, the unit may operate longer than usual, raising the temperature. This is fine. However, if the compressor does not turn off for more than 2-3 hours in a row, and the temperature in the chamber has already dropped to +2...+4°C, this is a signal that the installed unit is not operating correctly.
Checking can be done using an external thermometer placed in a glass of water in the center of the chamber. Let the refrigerator run for a day. If the thermometer readings correspond to the set values on the regulator handle, then the replacement was successful. If the temperature fluctuates or does not reach the desired values, it may be necessary to adjust the quality screw located on the thermostat housing (usually it is closed with a seal or plug).
In models with electronic control, such as Pozis RK-139, after replacing the thermistor, it may be necessary to reset errors in the controller memory. To do this, sometimes it is enough to simply unplug the refrigerator for 15-20 minutes. If the error persists, perhaps the problem is not in the sensor, but in the control module itself.
- 🌡️ Check the temperature in different zones of the chamber: it should be colder at the back wall, warmer at the door.
- 🔊 Listen to the operation: there should be no extraneous vibrations or frequent switching on/off (clocking).
- ❄️ Make sure that condensation or an ice crust does not form on the food, which indicates a correct defrost cycle.
⚠️ Attention: If after replacing the thermostat the refrigerator started working, but after a few days it stopped freezing again, do not rush to blame the new part. Check the tightness of the circuit and the amount of refrigerant. Often, replacing the thermostat is only a temporary measure in the event of a freon leak, when the compressor simply cannot gain pressure to turn off.
A correctly installed and configured thermostat ensures a long life for the compressor and the safety of your products. Do not neglect regularly checking the temperature conditions, especially in the hot season, when the load on the cooling system increases.
Frequently asked questions (FAQ)
Is it possible to use a thermostat from another manufacturer, for example, TAM instead of T-133?
Yes, in most cases this is possible if the mounting dimensions, capillary tube length and contact type match. TAM-133 and T-133 are complete analogues and are often interchangeable in refrigerators Position. However, it is better to select a part with a similar temperature range indicated in the marking.
Why does the new thermostat click, but the refrigerator does not turn on?
The click means that the contacts open or close, but the current does not pass further. The reasons may be a malfunction of the compressor start relay, a break in the motor windings, or poor contact in the connection circuit of the thermostat itself. It is necessary to test the circuit with a multimeter.
How to determine that the thermostat is “lying” and shows the wrong temperature?
For this you need an external thermometer. Place it in the refrigerator next to the thermostat. If the handle is set to +5°C, and the thermometer shows 0°C or +10°C, and adjusting the quality screw does not help correct the situation, it means that the calibration is broken and the part must be replaced.
Is it dangerous to change the thermostat yourself in a refrigerator with a No Frost system?
Replacing a sensor (thermistor) in a No Frost less dangerous because there is no capillary tube with gas. However, there are more electronics and more difficult to access. The main thing is not to damage the plastic air ducts and connect the connectors correctly. A mechanical thermostat in No Frost is rare, usually in the refrigerator compartment area.
How long does the thermostat in a Pozis refrigerator last on average?
The average service life of a mechanical thermostat is 5-7 years of intensive use. Electronic sensors can last longer, up to 10 years, but they are more sensitive to power surges. Regular temperature changes (frequent defrosting) also reduce the service life of the part.