The situation when the refrigerator Ariston stops maintaining the temperature correctly, often baffling the owner. Products begin to deteriorate, an ice crust forms on the walls, or, conversely, the device works non-stop. In most cases, the culprit of these problems is a failed thermostat. This is a key element of the control system that controls the operation of the compressor depending on the temperature inside the chambers.
Replacing this component is a task that you can do yourself if you have basic skills in working with tools and strictly follow safety precautions. It is important to understand that there are refrigerants inside the refrigerator, and the electrical network poses a potential threat if handled carelessly. The exact model of your thermostat must match the marking of the old device, since the length of the capillary tube and the temperature range may vary. In this article we will analyze in detail the process of diagnostics, dismantling the old sensor and installing a new one.
Before starting disassembly, you need to make sure that the problem lies precisely in the mechanics or electrics of the regulator, and not in a freon leak or a compressor malfunction. Often users confuse the symptoms, which leads to the purchase of unnecessary spare parts. We will look at the characteristic signs of failure, which indicate the need to replace the thermostat in refrigerators of the brand Ariston.
Signs of a malfunction of the thermostat
You can determine that the thermostat has failed by a number of specific symptoms that appear in the operation of the refrigerator. If you notice that the compressor is running continuously without turning off for hours, this is the first alarm signal. In normal mode, the engine should periodically stop, giving the system a rest. Also, the alarm should be sounded if a “snow coat” has formed inside the chamber or food begins to freeze even at minimum power settings.
The opposite situation, when the refrigerator does not turn on at all or turns on for a very short time, may also indicate a problem with the contact group of the regulator. In this case, the electrical signal simply does not reach the compressor start relay. To confirm the diagnosis, you can carry out a simple check: if, when the contacts are forced to close, the compressor starts and operates, it means that the control circuit is broken in the thermostat unit.
It is worth noting that some models Ariston are equipped with electronic control modules, where the thermostat function is performed by a temperature sensor. However, in classical mechanical systems, which most often require repairs, it is the capillary thermostat that is used. Its breakdown is often associated with depressurization of the bellows or sticking of contacts due to overloads.
Necessary tools and preparation
For successful repair work, it is necessary to prepare the appropriate equipment in advance tools. Lack of the necessary tools may delay the process or lead to damage to the plastic elements of the case. You will need a standard DIY kit, which many people have in their garage.
The list of tools includes:
- 🔧 A set of screwdrivers (phillips and flathead) for removing panels and terminals.
- 🔪 A sharp knife or scalpel for careful removal of insulation (if required).
- 🧤 Dielectric gloves to protect against possible residual voltage.
- 🔦 Flashlight for illuminating the interior of the refrigerator.
- 🧼 Clean rags for wiping contacts and removing condensation.
Particular attention should be paid pay attention to safety. Before starting any work, the refrigerator must disconnect the power. Unplug the power cord from the outlet. This is a critical step because working with live electrical wiring is prohibited. It is also recommended to defrost the chamber if a lot of ice has accumulated in it, so that water does not get on the electrical contacts during dismantling.
⚠️ Attention: Do not try to remove the thermostat by force. The capillary tube is very thin and easily breaks, and its damage will require a complete replacement of the unit or complex refilling of the system.
Location and access to the thermostat
In refrigerators Ariston the thermostat is most often located inside the fridge compartment. The exact location depends on the year of manufacture and the specific model series. In most cases, it is hidden behind a plastic panel or is located directly in the temperature control unit, which can be combined with a lampshade.
To gain access to the unit, it is often necessary to remove the temperature control knob. It can be removed by simple force or have a hidden locking screw under a decorative plug. In some modifications, it is necessary to remove the top cover of the refrigerator or the side panel if the regulator is placed outside, although Ariston the internal location is more typical.
After removing the handle and decorative trims, access to the thermostat itself will open. This is a metal or plastic case, from which comes a bundle of wires and a thin copper tube - capillary. The tube is usually secured with special clips to the evaporator or chamber wall. Carefully inspect the fasteners to understand the logic of disassembly without sharply pulling the wires.
The process of dismantling the old device
The most critical stage is removing the faulty element. You need to start by disconnecting the electrical wires. Before doing this, we strongly advise you to take a photo of the connection diagram or sketch it, so that when installing a new thermostat you do not confuse the colors. Each wire is responsible for a specific function: power, ground, signal to the compressor.
Use pliers or a screwdriver to carefully remove the terminals from the thermostat contacts. Be careful not to damage the wire insulation. After disconnecting the electrical part, it is necessary to free the capillary tube. It can be threaded through a hole in the chamber wall or secured to the evaporator with plastic brackets.
If the tube passes through the wall, it must be pulled very slowly and smoothly from the inside out. Sudden movements can lead to a break in the tube inside the insulating layer, which will make repairs impossible without calling a specialist with vacuum equipment. After releasing the capillary, unscrew the fixing screws of the thermostat housing and remove it from the seat.
☑️ Removal checklist
Installing and connecting a new thermostat
Installation of the new regulator is carried out in the reverse order of dismantling. Make sure that the new thermostat has the same geometric dimensions and capillary tube length. If the tube is longer, you can carefully roll it into a ring, but in no case bend it or shorten it. The bending radius must be at least 5 cm so as not to disrupt the permeability of the refrigerant inside the capillary.
Insert the sensitive element (capillary) into the hole in the wall or attach it to the evaporator in the same way as the old sensor was attached. The contact between the sensing element and the surface whose temperature it measures must be tight. Often, a special heat-conducting paste is used for this or they are simply pressed tightly with a metal strip.
Connect the wires according to a previously made diagram or photograph. Color coding is usually standard, but it is better to double-check the documentation for the specific model Ariston. Tighten the housing mounting screws and install the adjustment knob in place. Make sure that the handle rotates freely and does not touch adjacent elements.
What to do if the wires are not the right length?
If the wires of the new thermostat are shorter, you can carefully extend them using soldering and high-quality insulation. However, it is best to avoid connections inside the humid compartment of the refrigerator. Ideally, the wires should be of such length that the twist or terminal block is located outside the chamber, in a dry technical compartment.
Checking and setting
After assembling all the elements, you can start testing. Plug in the refrigerator. In the first minutes, the compressor may not start immediately - this is normal for some protection systems. After 5-10 minutes you should hear the characteristic hum of the engine. If the refrigerator is working, monitor its operation cycle.
The table below shows the main parameters for checking the correct operation after replacement:
| Check parameter | Normal value | Possible problem |
|---|---|---|
| Operation time before shutdown | 20-40 minutes | Thermostat faulty or freon leak |
| Downtime | 15-30 minutes | Thermal insulation is broken or the door does not close |
| Temperature in the chamber | +2...+5 °C | Incorrect calibration of the new regulator |
| Frost on the back wall | Uniform, without “fur coats” | Sticking thermostat contacts |
If the refrigerator turns off when the desired temperature is reached and turns on automatically when it rises, then the replacement was successful. The adjustment is made experimentally: if the food freezes, turn the knob towards lower values, if the temperature is too high - towards higher values.
Typical errors when replacing
Even following the instructions, beginners often make mistakes that can negate all efforts. One of the most common is incorrect installation of the capillary tube. If it does not fit tightly to the surface to be cooled or hangs in the air, the thermostat will show the wrong temperature and the compressor will not work correctly.
Another common mistake is poor contact in electrical connections. It is not enough to just put the terminal on, it must fit tightly. Oxidized contacts can cause repeated failure or sparking. Also, do not ignore the condition of the wire insulation: if it is damaged, moisture inside the chamber can cause a short circuit.
⚠️ Attention: Never use thermostats from other refrigerator models without checking the characteristics. A different on/off temperature range will either spoil the food or overload the compressor.
Sometimes users forget to check the condition of the door seal after repair. If the door does not close tightly, the cold escapes and the thermostat causes the compressor to run constantly, which may be mistakenly perceived as a malfunction of the new part. Always check the chamber for leaks.
Is it possible to repair an old thermostat or just replace it?
At home, repairing a mechanical thermostat is practically impossible and impractical. The device is sealed, and violation of its integrity will lead to final failure. In addition, calibration of springs and contacts requires special equipment. The only thing that can be done is to clean the contacts if they have oxidized, but this is a temporary measure.
Why does the new thermostat click, but the refrigerator does not turn on?
The click means that the contacts are closed, but the compressor does not start. This may indicate a malfunction of the start relay, the compressor itself, or an open circuit in the power supply. It is also possible that the new thermostat is faulty or not wired correctly. It is necessary to test the circuit with a multimeter.
How often do you need to change the thermostat in an Ariston refrigerator?
The service life of the thermostat is usually 5-7 years, but depends on operating conditions. Frequent voltage surges, high humidity and mechanical stress can shorten this period. Scheduled replacement is not required; change only when signs of malfunction appear.