Sudden shutdown compressor or, conversely, its continuous operation often indicates a failure of one of the key elements of the control system - the thermostat. This small device is responsible for maintaining a set temperature inside the chambers, opening and closing the electrical circuit depending on the sensor readings. When thermostat stops responding correctly to changes in thermal conditions, food begins to deteriorate or freeze, and energy bills rise.
Many home craftsmen with basic skills in working with tools can replace this part on their own. However, the process requires attention to detail, since different refrigerator models Indesit, Atlant or Bosch have their own design features. Incorrect installation can lead to compressor breakdown or system leakage.
Before proceeding with disassembly, you need to make sure that the problem lies in the temperature controller, and not in a freon leak or a malfunction of the start relay. In this article, we will analyze the stages of diagnostics, selection of analogues and direct replacement of the device so that you can return your refrigerator to functionality.
Diagnostics of a thermostat malfunction
The first sign of a breakdown is often the absence of a characteristic click when turning the adjustment knob. If you turn the switch and there is no sound or the compressor does not start, this may indicate an open circuit or stuck contacts. However, in some models with electronic control, the click may not be heard at all, so you should not rely on hearing alone.
A more reliable test method is visual inspection and testing the contacts with a multimeter. To do this, it is necessary to dismantle the device and cool its sensitive tube (capillary) for 15-20 minutes by placing it in the freezer or applying it to a cold source. If after cooling the contacts do not close and the multimeter shows an open circuit, thermostat it is faulty and requires replacement.
⚠️ Attention: Before any diagnostics, be sure to disconnect the refrigerator from the power supply. Working with live electrical wiring is deadly.
Another symptom is that the refrigerator works nonstop, not turning off for days. In this case, the thermostat contacts are stuck in the closed position, and the device does not send a signal to turn off the compressor when the temperature has reached normal. This leads to freezing of food and excessive load on the engine.
Preparing tools and selecting spare parts
For successful repairs, you will need a minimum set of tools. The main attention should be paid to the selection of compatible spare parts, since thermostats have different capillary tube lengths and types of mounting. An incorrectly selected part may not fit into the normal place or have the wrong temperature range.
You will need the following tools:
- 🔧 Screwdrivers (phillips and flat) for dismantling panels.
- 🔌 Pliers or pliers for working with terminals.
- 🧊 Hair dryer (construction or household) for defrosting ice if it interferes with access.
- 📏 Multimeter for checking the circuit (optional, but desirable).
When choosing a new part, pay attention to the markings of the old device. It is usually applied to the body or metal plate. The key parameters are the operating temperature range and the length of the capillary tube. If you cannot find an exact analogue, it is possible to install a universal thermostat, but calibration may require additional settings.
Where to look for the markings?
The marking is usually applied to the metal body of the thermostat or to the plastic handle. Look for codes like TAM-133, K-59, L-338. The numbers after the letter designation indicate the length of the capillary tube in centimeters (for example, 1.3 meters or 0.8 meters).
Access to the thermostat in different models
The location of the thermostat depends on the design of the refrigerator. In most modern models, it is located inside the refrigerator compartment, often hidden behind a plastic panel or built into the lampshade. In older models, such as some series ZIL or Minsk, the regulator can be located outside, on the top of the case.
For access to the internal thermostat in refrigerators Indesit i Stinol often it is necessary to remove the plastic cover, which is secured with latches. You need to act carefully so as not to break the fragile plastic. In models Atlant and Beko the thermostat can be combined with a light bulb, and to remove it you need to unscrew the screws holding the lamp.
In some cases, access to the mounting point is difficult due to frozen ice. If you see that an ice crust has formed around the seat, do not try to chip it off with a knife - you may damage the evaporator. It is better to use a hairdryer or let the ice thaw naturally, placing a rag to absorb water.
☑️ Preparation for dismantling
The process of dismantling the old device
After access to the thermostat is obtained, it is necessary to fix the current position of the wires. Take a photo or draw a connection diagram so that when installing a new part you do not mix up the terminals. Typically, three contacts are used: one for grounding (if any) and two for breaking the phase.
Carefully remove the terminals from the thermostat contacts. If they are oxidized or are sitting very tightly, you can move them slightly with pliers, but without excessive force. Then disconnect the capillary tube itself. It can be simply inserted into the hole or secured with a pressure plate.
When pulling out the old thermostat, be careful with the capillary tube. It is very thin and bends easily. If the tube becomes damaged, the refrigerant inside it will escape and the appliance will stop working. Remove the device smoothly, turning it around its axis to release it from its seat.
⚠️ Attention: The capillary tube is filled with refrigerant under pressure. Do not bend it, hit it or heat it with an open fire, as this may lead to depressurization.
Installation and connection of a new thermostat
Installation of a new device is carried out in the reverse order of dismantling. Insert the sensing tube into the hole as far as it will go, ensuring that it goes in to the same depth as the old one. The depth of immersion directly affects the accuracy of temperature readings.
Connect the wires to the contacts according to the diagram or photograph made earlier. If the wire colors match, there shouldn't be any problems. If you use a universal thermostat with a different color marking, be guided by the logic of operation: the common wire and the wire going to the compressor must close the circuit during cooling.
Fix the thermostat housing in its original place. Make sure it fits snugly and doesn't wobble. After this, reinstall the plastic panels, lampshades and adjustment knobs. All latches should snap into place with a characteristic click.
Setting up and checking operation
After assembly, turn on the refrigerator. Let it run for 30-40 minutes. At this time the compressor should turn on and start cooling. If after a while you hear the click of the motor turning off, it means thermostat it worked correctly.
Check the temperature in the chambers using an external thermometer. Place it on the middle shelf of the refrigerator. After a few hours, the readings should stabilize in the range of +2 to +6 degrees Celsius. If the temperature differs significantly, adjust the position of the screw under the seal (if there is one) or recheck the installation.
The following is a table of common problems and their possible causes after replacement:
| Symptom | Possible cause | Solution |
|---|---|---|
| The refrigerator does not turn on | Incorrect wire connection | Check the circuit and contacts |
| The compressor runs without stopping | The capillary tube is not fully inserted | Immerse the tube deeper into evaporator |
| Temperature too low | Incorrect calibration or thermostat type | Adjust with a screw or replace with the correct one |
| Crackling noise is heard during operation | Poor fastening housing | Tighten the screws or check the latches |
If the problem does not disappear after replacement, the problem may lie deeper - in the start relay, the compressor itself, or in the refrigerant circulation system. In such cases, it is recommended to contact professional technicians for a more in-depth diagnosis.
Frequently asked questions (FAQ)
Is it possible to replace the thermostat with universal if the original is discontinued?
Yes, in many cases this is possible. Universal thermostats (such as the TAM or K series) often have an adjustable temperature range and a removable capillary tube that can be cut to the desired length. The main thing is to make sure that the current characteristics of the contacts are suitable for the power of your compressor.
Why does the new thermostat click, but the refrigerator does not freeze?
The click means that the electrical circuit is closed and a signal to turn on is given. If the compressor hums but does not start, or is silent, the problem may be with the start relay, the capacitor, or the compressor itself. It is also worth checking whether voltage is being supplied to the engine terminals.
Is it necessary to release freon before replacing the thermostat?
No, it is not necessary. The thermostat is part of the electrical control circuit and does not come into direct contact with the refrigerant inside the system. The capillary tube is sealed and filled with a separate coolant substance (often an inert gas), which reacts to temperature, but does not mix with freon in the cooling circuit.
How to determine that the thermostat is “lying”?
For this, an external thermometer is used. If the regulator is set to the average value, and the food in the chamber freezes or, conversely, spoils from the heat, then the calibration is broken. In mechanical thermostats, this is often treated by tightening the adjusting screw hidden under the seal.