A sudden breakdown of the refrigerator is always stressful, especially when there are perishable foods left inside. One of the most common causes of failure is a thermostat failure, which stops sending the signal to the compressor to turn on or off. As a result, the unit either remains silent and does not cool, or works without interruption, turning into an icy monolith. Understanding how to choose a thermostat for a refrigeratorbecomes a critical skill for an owner who wants to save money on service.
Replacing this component does not require deep knowledge of electrical engineering, but does require attention to detail. An incorrectly selected temperature controller can lead to incorrect operation of the entire system, food spoilage, or even damage to the compressor. In this article, we will analyze in detail the principle of operation of the device, how to decipher the markings and the nuances of installation.
Before going to the store or placing an order, it is necessary to accurately identify the failed part. The market offers many analogues, and confusion in models is unacceptable here. Thermoregulator is a precise device that responds to the slightest changes in temperature in the chamber.
Each manufacturer of refrigeration equipment uses specific components, which may differ in the length of the capillary tube, operating temperature range and type of fastening. Ignoring these parameters will lead to the fact that the new element simply will not fit into place or will not work correctly. Let's look at the main types of faults that indicate the need for replacement.
⚠️ Attention: Before starting any work on diagnosing or replacing the thermostat, be sure to disconnect the refrigerator from the power supply. Working with live electrical wiring is deadly.
Symptoms of a malfunctioning thermostat
Diagnostics begins long before disassembling the unit. The behavior of the refrigerator itself will tell you where the problem lies. If you notice that the compressor is humming continuously, without turning off for hours, and the food in the chamber is frozen, most likely the sensor is “stuck” in the “on” position. This is a classic sign that thermostat contacts do not open when the set temperature is reached.
The reverse situation is also possible and occurs even more often. The refrigerator is silent, it’s warm inside, the light is on, but there is no cold. If, when turning the regulator knob to the extreme position (maximum cold), a characteristic click does not occur, the circuit is not closed. In this case thermostat requires replacement. However, it is worth remembering that similar symptoms may indicate a breakdown of the start relay or the compressor itself.
There is another indirect sign - turning the motor on and off too often. This may indicate that the sensor's response range has gone astray and it responds to minimal temperature fluctuations. It is also worth paying attention to condensation or ice inside the chamber if they appear where they should not be.
For an accurate check, you can use a multimeter in dial mode. At room temperature, the contacts should be closed (if it is a regular thermostat), and when the sensitive element cools, they should open. If the device shows an open circuit or, conversely, a short circuit in any conditions, the part is faulty.
Types of thermostats and their features
In modern and old refrigerators, mainly two types of thermostats are used: mechanical and electronic. Mechanical models, such as the well-known DANFOSS or Thermostatseries, work based on the expansion and compression of a gas or liquid inside a capillary tube. These are reliable, time-tested devices that are easy to repair and replace.
Electronic thermostats are complex modules with resistance sensors. They are often integrated into the overall refrigerator control board. If your unit controls the temperature via a digital display, then most likely you have an electronic type. Replacing such an element requires not only selection according to the model, but often also reprogramming or complex calibration.
Mechanical regulators are divided by the type of freon they work with (R12, R134a, R600a) and by temperature range. There are models for single-chamber refrigerators, for double-chamber refrigerators (with separate adjustment) and for freezers. It is important to understand that the thermostat from the freezer is not suitable for the main compartment due to different response temperature ranges.
Particular attention should be paid to the mounting design. Some models have a standard threaded hole, others are mounted with latches or special brackets. The length and diameter of the capillary tube are also important: a too long one can be carefully rolled up, but a short one cannot be extended.
Can a universal thermostat be used?
Universal thermostats exist, but they often have average characteristics. Their installation is possible as a temporary solution, but for long-term and stable operation it is better to look for an original analogue or a high-quality substitute with identical response parameters.
Deciphering markings and compatibility
The most difficult stage is finding an analogue. Manufacturers use different coding systems, but the most common are markings starting with letters TAM, K, T. For example, the company's popular thermostats Ranco have markings like K59-L1234, where letters indicate the series and numbers indicate specific characteristics.
Marking TAM is often found on analogues for refrigerators Indesit, Ariston, Stinol. The numbers after the letters indicate the length of the capillary tube and the temperature range. For example, TAM-133 and TAM-145 may differ in turn-on and turn-off temperatures, which is critical for proper operation.
Series K (for example, K-50, K-59) is a classic from DANFOSS. They were installed in a huge number of Soviet and European refrigerators. Here it is important to pay attention to the last digit or letter index, as they determine what refrigerant the device is intended for.
Below is a table of correspondence between some popular models and their analogues, which will help you navigate your search:
| Original | Analogue 1 | Analogue 2 | Application |
|---|---|---|---|
| TAM-133 | K-59 L1102 | 17D9TAM133 | Single-chamber refrigerators |
| TAM-145 | K-59 L1108 | 17D9TAM145 | Double-chamber (refrigerator compartment) |
| TAM-112 | K-56 L1101 | 17D9TAM112 | Freezers |
| T-110 | T-111 | T-112 | Soviet refrigerators |
When selecting an analogue, always check not only the letter code, but also the length of the capillary. If you take a thermostat with a 1.5 meter tube instead of 2.5, you may not have enough length for proper installation in the chamber, which will lead to incorrect temperature readings.
Instructions for replacing the thermostat
The replacement process begins with dismantling the old element. Depending on the design of your refrigerator, the thermostat may be located inside the chamber (under the plastic cover of the adjustment knob) or outside, in the technical compartment. In the first case, you will need to remove the plastic plug, unscrew the screw and carefully remove the handle.
After removing the decorative elements, access to the thermostat housing will open. It is necessary to photograph the wiring diagram so that when installing a new element you do not mix up the contacts. Then the wires are disconnected and the retaining nut holding the housing is unscrewed.
The most delicate part of the work is removing the capillary tube from the evaporator. It can be simply inserted into the hole or secured with a clamping bar. You need to pull it out very carefully, without sharp jerks, so as not to damage the thin tube and not to break the tightness of the system.
☑️ Checklist before replacement
Installing the new thermostat is done in the reverse order. The capillary tube is carefully inserted into the hole until it stops, the body is fixed with a nut, and the wires are connected according to the photograph taken earlier. Pay special attention to grounding if it is provided for in the design.
⚠️ Attention: Under no circumstances bend the capillary tube at an acute angle or damage it. This will lead to leakage of sensitive liquid and complete inoperability of the thermostat.
Setting and calibration after installation
After the new thermostat is installed and the refrigerator is assembled, it is necessary to carry out the initial setup. Do not immediately load food into the chamber. Let the unit run idle for at least 2-3 hours. This will allow the system to enter operating mode and stabilize the temperature.
Initially it is better to set the regulator knob to the middle position. If the refrigerator starts to freeze too much or, conversely, does not get cold, adjustments will be required. Some models of thermostats have a calibration screw under the seal, but it is not recommended to touch it without special equipment (thermometer and pressure gauge).
In domestic conditions, adjustment is made by selecting the position of the handle. If food in the refrigerator compartment freezes at the back wall, turn the knob towards lower values. If the temperature is too high, add cold. The process may take up to a day to fully stabilize.
Frequent errors in selection and installation
One of the most common mistakes is ignoring the type of refrigerant. Thermostats designed for freon R134ahave different response characteristics than models for R600a (isobutane). Installing an unsuitable element will result in the refrigerator operating inefficiently or constantly freezing.
Another mistake is incorrect installation of the capillary tube. It must be placed so that it fits tightly to the evaporator in a specially designated channel or is pressed with a bar. If the tube hangs in the air of the chamber, the thermostat will respond to the air temperature, and not to the evaporator temperature, which will cause the compressor to turn on chaotically.
Also, users often forget to check the integrity of the door seals after repairs. If the door does not close tightly, no thermostat, even the newest one, will be able to maintain the set temperature, and the compressor will wear out.
Is it possible to replace the thermostat with a universal one if the original is removed from production?
Yes, it is possible, but you need to be very attentive to the parameters. Universal thermostats (for example, the K59 or TAM series with average characteristics) are often suitable in size and thread. However, the temperature range may vary. If you set a thermostat with a lower shutdown threshold, the food may freeze. It is better to look for cross-tabs of correspondence for your specific refrigerator model.
Why does the new thermostat click, but the compressor does not start?
This may indicate a problem not with the thermostat, but with the start relay or the compressor itself. The thermostat only completes the circuit. If there is a click (the circuit is closed), but the motor is silent, it means that the current does not reach the windings or the motor is faulty. It is also worth checking the integrity of the wires themselves coming from the thermostat.
Is it necessary to defrost the refrigerator before replacing the thermostat?
Complete defrosting is desirable, especially if access to the evaporator is difficult due to ice. However, if the capillary tube is brought out through a hole in the back wall of the chamber, you can sometimes avoid complete defrosting by carefully removing the old sensor. But to properly clean the channel and check the condition of the evaporator, it is better to let the ice melt.
How can you tell that the thermostat is “lying” and shows the wrong temperature?
If you set the middle position, and within an hour a coat of ice forms on the food in the chamber, or vice versa - the room is warm, but the compressor is silent, most likely the calibration is broken. This can only be checked using an external thermometer, comparing the readings of the handle and the actual temperature.