If your refrigerator stops turning off, works without interruption, or, conversely, stops cool, most often the problem lies in the temperature control system. Thermostat (or thermostat) is a key unit that is responsible for turning the compressor on and off depending on the temperature inside the chambers. When this element fails, the entire cooling cycle is disrupted, which can lead to spoilage of food or even defrosting of the contents of the freezer.
Independent replacing the thermostat is a very real task for a home craftsman who has basic skills in working with tools and electrical circuits. However, it is important to understand that the process requires care, since it is necessary not only to physically install the new part, but also to correctly configure its operating range. In this article, we will analyze all the stages: from diagnostics to final calibration, so that you can safely bring the equipment back to life.
Before you begin disassembling, you need to make sure you have the necessary tools and, most importantly, safety. Installing the refrigerator thermostat always starts by disconnecting the device from the power supply. Ignoring this rule may result in electric shock as you will be working with live contacts. Prepare a multimeter, screwdrivers, pliers, and possibly new refrigerant if soldering is required (although this is rarely necessary when simply replacing the regulator).
⚠️ Attention: Before starting any work, be sure to unplug the refrigerator from the outlet. Working with live electrical components is deadly.
Diagnostics of a thermostat malfunction
Before buying a new part, you need to make sure that this is the problem. Symptoms may be similar to a compressor failure or freon leak. The main sign of a malfunction thermostat is either constant operation of the motor (the refrigerator hums and does not turn off), or complete silence of the unit when there is power in the outlet. In the first case, the contacts could “stick” in the closed position, in the second, an opening has occurred and the reverse connection of the circuit does not occur.
For an accurate check, multimeteris used. You need to remove the thermostat and “ring” its contacts. In the normal state (at room temperature), the contacts should be closed, and the device will show zero or a resistance value close to it. If the multimeter shows “infinity” (break), then the part is faulty and requires replacement.
There is also a simple visual and tactile test method that does not require complex instruments, but gives only a preliminary result. You can place the thermostat capillary tube in a container of ice water. If after some time a characteristic click is heard, the mechanism is working. However, such a test does not guarantee the correct operation of the part inside the refrigerator body under load.
Selecting a suitable analogue and preparation
Selecting the right one thermostat is a critical stage. These parts are not universal: they differ in the length of the capillary tube, the type of fastening, the location of the contacts and the operating temperature range. Installing an unsuitable model can lead to incorrect operation of the compressor or damage to the evaporator.
When purchasing, pay attention to the markings of the old device. Manufacturers often use standard codes, for example, series TAM, K, R or DF. It is also important to measure the length of the capillary tube - it should be equal to or slightly longer than the original one so that it can be correctly placed in the evaporator.
Here are the main parameters that need to be checked before purchasing:
- 📏 Capillary length: must correspond to the original so that the temperature sensor reaches the desired area of the evaporator.
- 🔌 Type of contacts: the number and location of terminals (2 or 3 contacts) must match for correct connection.
- 🌡️ Temperature mode: different response ranges are used for single-compressor and double-compressor models.
- 🔩 Type of fastening: check how the regulator body is attached to the wall of the refrigerator (screws, latches, brackets).
Where to find the thermostat markings?
The marking is usually applied to metal body of the thermostat. This can be a set of letters and numbers, for example, K59-L1102 or TAM133. Also, the part number is often indicated in the technical documentation of the refrigerator or on a sticker inside the chamber.
Removing the old thermostat
The process of removing the old regulator depends on the design of your refrigerator. In most models with a “crying” evaporator, the thermostat is located inside the refrigerator compartment. To get to it, you will need to remove the plastic cover covering the light bulb or temperature controller, as well as dismantle the internal panel.
If we are talking about the system No Frost, the thermostat (or air sensor) is often located behind the back wall of the refrigerator compartment or in the upper part where the control unit is located. It is important to act carefully here so as not to damage the fragile plastic and insulation.
Sequence of actions for dismantling:
- Disconnect the refrigerator from the mains and empty the refrigerator compartment of food.
- Remove the temperature control knob and decorative trim.
- Unscrew mounting screws holding the thermostat housing.
- Carefully pull the capillary tube out of the evaporator (be careful not to damage it and prevent freon leakage).
- Take a photo of the wiring diagram before disconnecting the terminals.
⚠️ Attention: Capillary The tube is very thin and fragile. Do not bend it at an acute angle or pull with force, otherwise you may damage the refrigerant circulation system.
Connection diagram and installation of a new element
Installation of a new thermostat is carried out in the reverse order of dismantling. The most important thing here is the correct connection of electrical wires. An error in the connection can lead to a short circuit or failure of the compressor. Use a photo or diagram taken earlier, if it is preserved.
The standard diagram usually contains the following contacts:
| Designation on the diagram | Wire color (often) | Function |
|---|---|---|
| 1, 2 | Red, Brown | Compressor power supply (main circuit) |
| 3, 4 | Green, Yellow | Grounding (not always involved in the regulator) |
| L | Black | Phase (power input) |
| C | Blue | Compressor (motor output) |
After connecting the electrical part, it is necessary to correctly position the capillary tube. Its sensitive end should fit tightly to the evaporator in a specially designated place (usually a hole in the back wall or a bracket on the evaporator tube). To improve heat transfer, special thermal paste is sometimes used, although in domestic conditions they often make do with tight pressing.
☑️ Ready for installation
Temperature setup and calibration
After the physical installation of the new part, the setup stage begins. The thermostat housing often has an adjustment screw hidden under a seal or plastic plug. It is designed to calibrate the temperature at which the compressor turns on and off.
Turning the screw clockwise usually increases the response temperature (the refrigerator will turn off at a higher temperature in the chamber), and counterclockwise it decreases it. However, you should not turn it unnecessarily: the factory settings are usually optimal for most situations.
To check the correct installation, use a thermometer placed in a glass of water in the center of the refrigerator compartment. After turning on the refrigerator, let it run for a few hours (the stabilization cycle may take up to 24 hours). The temperature in the main chamber should be kept within +2...+5°C, and in the freezer - -18°C and below.
Checking the system functionality
The final stage is testing. After assembling all the panels and turning on the refrigerator, listen to the operation of the compressor. It should start in a few seconds or minutes (depending on protection). After some time, when the temperature in the chamber reaches the set value, the motor should turn off with a characteristic click.
Pay attention to the duration of the work and rest cycles. The normal mode is when the refrigerator operates about 30-40% of the time (working time coefficient). If it works constantly or turns off too often (every 2-3 minutes), it means that the thermostat is configured incorrectly or is selected incorrectly.
Also check for the absence of extraneous noise and vibrations. Sometimes a loose thermostat or a vibrating capillary tube can create a humming noise that will be annoying in quiet conditions.
⚠️ Attention: If, after replacing the thermostat, the refrigerator begins to operate abnormally (too long or in cycles that are too short), turn it off immediately and recheck the capillary tube installation and screw settings.
Frequently asked questions (FAQ)
Is it possible to install a thermostat with a longer capillary tube?
Yes, it is possible if the tube is longer than the original. The excess length is carefully rolled into a ring and placed inside the body or in free space, being careful not to bend it. The main thing is that the sensitive end is located exactly in the right place on the evaporator. It is strictly forbidden to shorten the tube - this will break the tightness of the system.
Why does the refrigerator not turn off after replacing the thermostat?
There may be several reasons: the adjusting screw is incorrectly adjusted, the capillary tube does not fit tightly to the evaporator (the sensor does not “feel” the cold), or a thermostat with an inappropriate temperature range has been selected. It is also worth checking to see if there is a freon leak, as the symptoms may be similar.
Does it need to recharge the refrigerator with freon when replacing the thermostat?
No, replacing the thermostat does not require intervention in the refrigerant circulation system. The capillary tube of the thermostat is not connected to the internal cooling system of the refrigerator; these are separate circuits. Soldering and refilling are required only when repairing the cooling system itself.
How often do you need to change the thermostat?
The service life of the thermostat is usually 5-10 years, but it can fail even earlier due to power surges, mechanical damage or manufacturing defects. This unit does not require a special scheduled replacement - only when malfunctions occur.
Can the thermostat click during operation?
Yes, a characteristic click when turning the compressor on and off is normal operation of the thermostat contacts. However, if the clicks occur very often (every few seconds) or are accompanied by a crackling sound, this may indicate a malfunction or incorrect setting.