Sudden defrosting of food or, conversely, the transformation of fresh vegetables into ice blocks are sure signs that there has been a failure in the temperature control system. Most often, the culprit of such anomalies is the thermostat (thermostat), which ceases to correctly read the temperature inside the chamber or close/open the electrical circuit of the compressor. Understanding how to check this unit can save you a significant amount of money on calling a technician and buying a new spare part.
Diagnostics of the thermostat is a process that is accessible even to a person without deep technical knowledge, if you follow caution and basic electrical safety rules. You don't have to be a professional electrician to do the initial inspection, but attention to detail is key. In this article, we will analyze all available diagnostic methods: from visual inspection to using a multimeter, and will also discuss the nuances of replacing the part.
⚠️ Attention: Any work related to disassembling the case and accessing electrical contacts should be carried out ONLY after the refrigerator has been completely disconnected from the power supply. Do not risk your life for diagnostics.
Signs of a thermostat failure
Before disassembling the refrigerator and getting tools, you need to make sure that the symptoms really indicate a thermostat failure. Users often confuse thermostat failure with a freon leak or a compressor malfunction, which leads to incorrect repairs. The thermostat is the “brain” that commands the motor to turn on or off, and if it is “blind,” the refrigerator operates chaotically.
There are a number of characteristic signs that most likely indicate a problem in the temperature control circuit. If you notice that your Indesit or Atlant is behaving strangely, compare the situation with the one described below. However, remember that an accurate diagnosis can only be made by a comprehensive check.
- 🧊 The refrigerator does not turn on: The compressor is silent, the light in the chamber is on, but there is no cold - this may mean that the thermostat contacts do not close.
- ❄️ Continuous operation of the motor: The unit hums without interruption, the temperature drops below normal, food freeze even in the main compartment.
- 💧 Increasing "fur coat": Ice or frost appears in the refrigeration chamber where it should not be, due to the fact that shutdown does not occur on time.
It is important to consider that the symptoms may vary depending on your unit design. In models with mechanical control, you may hear a characteristic click that was not there before, or, conversely, not hear it at all. In electronic systems Problems can be displayed as error codes on the display, but often the system simply stops responding to adjusting the knob.
⚠️ Attention: If the refrigerator is equipped with a No Frost system, then the lack of cold when the compressor is running may indicate a malfunction of the damper or defrost sensor, and not just the main one thermostat.
Preparation for diagnostics and safety measures
A high-quality check of the refrigerator thermostat is impossible without proper preparation of the workplace and compliance with safety precautions. Chaotic actions can lead to damage to the wire insulation or, worse, to electric shock. Even if you are confident in your abilities, ignoring basic safety rules is unacceptable.
The first step should always be complete deenergization the device. Simply turning off the button on the case is not enough - you need to unplug the plug from the socket. After this, let the refrigerator stand for 10–15 minutes so that the remaining current in the condensers dissipates and the pressure in the refrigerant system equalizes.
☑️ Checklist for preparing for repairs
To carry out the work you will need a minimum set of tools. In most cases, a Phillips screwdriver is sufficient to remove the covers and pliers. However, for professional diagnostics it is critically important multimeter (tester), without which checking the electrical integrity of the contacts will be impossible. It also doesn’t hurt to have a flashlight, since refrigerator niches are often dark.
- 🔧 Tools: Screwdrivers (phillips and flat-nose), pliers, knife for stripping contacts (if necessary).
- ⚡ Device: Multimeter (ohmmeter) to check resistance and continuity of the circuit.
- 📸 Gadgets: Smartphone for photographing the wiring diagram before disconnecting them.
Pay special attention to the condition of the wires. If you see melted insulation or oxidized contacts, this may not only be due to a broken thermostat, but also to a poor connection causing heat. In such cases, replacing the regulator alone may not solve the problem completely.
Visual inspection and search for the thermostat
The location of the thermostat depends on the model and year of manufacture of the refrigerator. In old models, such as Soviet ZIL or early Minsk, it is often located inside the refrigerator compartment and covered with a plastic casing. In more modern units, for example Bosch or LG, the thermostat can be hidden behind the rear panel or even moved outside, under the hood with a compressor.
If the thermostat is located inside the chamber, you You need to carefully remove the plastic temperature switch knob. Usually it is simply pulled together by hand or pryed with a flat screwdriver through a special hole. Under the handle you will see a nut that needs to be unscrewed to gain access to the body of the device.
If the thermostat is located outside (in the engine compartment), you need to remove the back cover of the refrigerator. Be careful as there may be sharp metal edges and fragile copper tubing. Find a small box to which the wires from the network and from the compressor come, and also goes out capillary tube - this is the desired node.
| Location | Where to look | Access features |
|---|---|---|
| Inside the camera | Under the lampshade or in the corner | You need to remove the handle and protective cover |
| Outside (rear) | Next to the compressor | Removal of the rear metal cover is required |
| In the door | At the end of the door (rarely) | It is necessary to remove the decorative pad |
During a visual inspection, pay attention to the integrity of the capillary tube. If there are traces of oil or mechanical damage on it, it means that the freon has come out of the bellows, and the thermostat is physically unable to respond to temperature changes. In this case, the part cannot be restoredonly replacement.
Checking the thermostat with a multimeter
The most reliable way to check the refrigerator thermostat is to use a multimeter in resistance (Ohm) or continuity measurement mode. This method gives an unambiguous answer about the state of the electrical contacts inside the device. First, you need to completely dismantle the thermostat, disconnecting all the wires (don't forget to take a picture of their location first!).
Set the multimeter to the dialing mode. Touch the probes to the two main contacts of the thermostat. At room temperature, the contacts should be closed and the device should beep or show resistance close to zero. If there is no signal, try turning the control knob all the way - sometimes the contacts can “stick.”
Multimeter mode: 200 Ohm or “Continuity” (speaker icon)Normal reading: 0 - 5 Ohm (There is sound)
Bad reading: 1 or OL (Open circuit, no sound)
The next stage of testing is the reaction to cold. Place the sensing part of the thermostat (capillary tube or bellows) in a container of ice water for 2-3 minutes. After this, call your contacts again. A working thermostat should break the circuit and the multimeter will stop beeping. If the circuit remains closed even in the cold, it means that the mechanism is “stuck” and requires replacement.
⚠️ Attention: Do not immerse the thermostat housing itself with the electrical leads in water! Lower only the metal sensor tube, having previously isolated the contacts from moisture.
Testing methods without a multimeter
What to do if there is no tester at hand, and the refrigerator needs to be repaired urgently? There is a popular testing method that allows you to evaluate the performance of the thermostat indirectly. It is less accurate, but in skillful hands it gives a sufficient understanding of the situation. The essence of the method is to exclude the thermostat from the circuit and observe the reaction of the compressor.
To do this, you need to connect the wires that went to the thermostat directly (short them together), after making sure that the refrigerator plug is unplugged from the socket. The connection must be reliable; it is best to use a twist insulated with electrical tape or a terminal block. After this, turn on the refrigerator.
- 🔌 The compressor started: This indicates that the motor itself and the start relay are working properly, and the problem, most likely, is in the thermostat (it did not give a command to start).
- 🔇 The motor is silent: If the compressor does not hum when connected directly, it means the problem is deeper - it is faulty the starting relay, the compressor itself, or there is a break in the wiring.
This method is good for initial diagnostics, but you cannot leave the refrigerator running with a shorted thermostat! Without temperature control, it will freeze until the thermal protection relay trips or the motor burns out. Use this method only for a short-term test (for 1-2 switching cycles).
Replacing and setting up a new thermostat
If the test confirms a malfunction, the only solution is replacement. When purchasing a new part, pay attention to the markings - it must match the original or be its complete analogue. There are no universal thermostats, since the length of the capillary tube and the temperature range for different models Samsung, Stinol or Beko may differ.
The installation process is the reverse of dismantling. Carefully route the capillary tube along the same path as it was before. Avoid kinking or kinking the tube, as this will lead to its depressurization. Secure the thermostat housing in its original place and connect the wires strictly according to the photograph taken earlier.
After installation, adjustment may be required. The body of a new thermostat often has three sealed screws, which are not recommended to be twisted without special equipment and knowledge. However, the screw responsible for the temperature range (usually marked or located separately) can be adjusted. If the refrigerator turns off too early or late, turn the screw half a turn and monitor the operating cycles throughout the day.
The final step will be to check the tightness and operation. Turn on the refrigerator and let it run for a few hours. Check if it gets cold and if the compressor turns off when the desired temperature is reached. If the operating cycles are stable, the repair can be considered successful.
Is it possible to repair the thermostat yourself?
Theoretically, you can try to clean the contacts or bend the spring, but in practice this is a temporary measure. The tightness of the bellows is broken during disassembly, which leads to leakage of the filler gas. Therefore, professionals recommend only a complete replacement of the unit.
Why does the thermostat click, but the cold does not turn on?
The click means that the mechanism has worked, but the contacts may be burnt and not conduct current, or the problem is in the compressor start relay. It is also possible that the compressor itself has failed (interturn short circuit).
How often should the thermostat be changed?
The service life of the thermostat is usually 5-10 years, but it depends on the intensity of use and power surges in the network. If the refrigerator is in a draft or is often opened, the service life of the part is reduced.
Does the type of refrigerant affect the choice of thermostat?
Yes, indirectly. Different refrigerants (R134a, R600a, R12) have different boiling and condensation temperature characteristics, so thermostats are calibrated for a specific freon and evaporator design.