How to check the thermostat of an Ariston refrigerator

The situation when the refrigerator Ariston stops turning off or, conversely, does not start at all, often causes panic among owners. However, in most cases, the cause is the failure of one of the simplest components - the thermostat. It is this element that is responsible for maintaining a given temperature regime by opening and closing the compressor power circuit. Before calling a technician or buying a new unit, it makes sense to carry out an initial diagnosis.

Checking the thermostat yourself can save significant money, since replacing this part is a procedure accessible even to a person with basic skills in working with tools. Thermoregulator (or thermostat) is a mechanical or electronic device that reads the temperature in the chamber and sends a signal to turn it on or off motor. If this signal is not received or is received incorrectly, the cooling cycle is disrupted.

In this article we will analyze in detail the algorithm of actions for identifying a malfunction, the necessary tools and safety measures. You will learn how to distinguish a broken thermostat from problems with the compressor or a freon leak, which is often confused even by experienced users. Correct diagnosis is the key to successful and inexpensive repair of your equipment.

Main signs of a malfunctioning thermostat

Understanding the symptoms is the first step to solving the problem. If thermostat is broken, the behavior of the refrigerator Ariston becomes predictable, but may vary depending on the type of failure (contact closure or breakage). Most often, users are faced with the fact that the unit works without interruption, trying to cool the chamber to unrealistically low temperatures, or is silent, despite the fact that it is already warm inside.

Pay attention to the following alarm signals that indicate the need for inspection:

• 🧊 Continuous operation: The compressor hums constantly, without going into rest mode, and a “coat” of ice forms on the back wall.
• 🔥 Lack of cold: The motor does not turn on at all, although the light is on and it is warm inside, and a characteristic click is heard when trying to start.
• 💧 Sharp temperature changes: Food either freezes in an ice ball, then begins to thaw, although you did not change the regulator settings.
• 🔌 Spontaneous shutdown: The refrigerator turns off itself, even if the chamber is not yet cold enough.

It is important to note that similar symptoms can also occur if there is a refrigerant leak or a faulty start relay. However, if during defrosting the situation does not change during the day, and the compressor is either “silent” or “roars” without stopping, the probability of failure is more than temperature sensor more than 80%. In models with mechanical control, the rotary knob itself or the internal spring often breaks.

⚠️ Attention: If the refrigerator makes strange sounds (gurgling, whistling) or does not make any sounds of the motor operating at all when plugged in, the problem may not be in the thermostat, but in the compressor or electrical circuit. Diagnostics in this case requires more in-depth knowledge.

Preparation for diagnostics: tools and safety

Before proceeding with disassembly and testing, it is necessary to ensure safe working conditions. Electric current poses a real threat, so the first and most important rule is to completely de-energize the device. No manipulations with internal components Ariston can be carried out while the power cord is plugged into the outlet.

To carry out high-quality diagnostics, you will need a minimum set of tools that are usually found in your home arsenal:

• 🔧 Multimeter (tester): A mandatory device for checking circuit integrity and resistance.
• 🪛 Screwdriver set: Cross and flat to remove protective covers and panels.
• 🧤 Gloves: To protect your hands from sharp edges and possible condensation.
• 📸 Smartphone: To photograph the wiring diagram before disconnecting them.

Pay special attention to access to the thermostat. In refrigerators Ariston it can be located inside the chamber (under the lamp shade or on the side wall) or outside, in the upper part of the case. If the thermostat is inside, you may need to pre-defrost the chambers to avoid damage to the plastic elements during dismantling.

⚠️ Attention: Do not use sharp objects (knives, awls) to pick out frozen parts or remove ice. This can lead to damage to the evaporator and a complete loss of system integrity.

When the tools are ready and the refrigerator is unplugged, you can begin to visually assess the condition of the wiring. Often the reason lies not in the sensor itself, but in oxidized contacts or a broken wire.

Removing the thermostat in Ariston refrigerators

The process of removing the thermostat depends on the design of your model Ariston. In older models with a top freezer, the thermostat is often located inside the refrigerator compartment. In more modern No Frost systems, access may be hidden behind decorative panels. The main thing is to act consistently and not use excessive force.

The algorithm for dismantling usually looks like this:

1. Remove all shelves and drawers that interfere with access to the unit.
2. If the thermostat is under the lamp shade, carefully pry it up with a flat screwdriver and disconnect wiring.
3. Remove the temperature regulator handle (sometimes it is simply pulled onto the rod, sometimes it is screwed on with a screw).
4. Unscrew the mounting screws holding the thermostat housing.
5. Carefully pull the sensitive tube (capillary) out of the evaporator, if it fixed in the hole.

At this stage, it is critical to remember or photograph which wire is connected where. Connection diagram may differ depending on the series of the refrigerator. Usually the wires are color-coded, but you shouldn’t rely only on color, since previous masters may have made changes.

How not to mix up the wires during assembly?

Take a close-up photo of the connection. If there are a lot of wires (3 or more), label them with a marker directly on the insulation or use masking tape with marks. This will save you hours of guessing when reassembling.

After removing the device, inspect it for visible defects: melting, burn marks, corrosion on the terminals. If the thermostat housing is swollen or cracked, its replacement is necessary without additional testing.

Checking the thermostat with a multimeter: step-by-step instructions

The most reliable way to determine the performance of a part is to ring its contacts with a multimeter. This method gives an accurate answer whether there is an open circuit inside the device. Switch the device to resistance measurement mode (Ohm) or continuity mode (with a sound signal).

Carry out the test strictly according to the following instructions:

• 🔌 Step 1: Connect the multimeter probes to the two main contacts of the thermostat (usually the input and output to the compressor).
• 🧊 Step 2: At room temperature, the contacts must be closed - the multimeter will show zero or a value close to it and make a squeak.
• ❄️ Step 3: Place the thermostat sensitive tube in a container with ice water (or apply to a frozen product) for 2-3 minutes.
• 🔇 Step 4: When cooling, the contacts should open - the resistance will go to infinity, and the squeaking will stop.

If at room temperature the circuit does not ring (resistance is infinite), then the contacts are inside oxidized or burnt, and the current does not pass. This means that the compressor will not receive a command to start. If the chain rings even after cooling with ice water, it means that the mechanism is “stuck” and does not open the circuit, which will lead to eternal operation of the motor.

For three-pin thermostats (with an indicator light), the check is a little more complicated. You need to find a pair of contacts that closes to cold and opens to heat, ignoring the contact going to the lamp.

Alternative testing methods without a multimeter

What to do if you don’t have a tester at hand, and the refrigerator needs to be repaired urgently? There is an elimination method that allows you to determine with a high degree of probability that the thermostat is malfunctioning by directly applying voltage to the compressor. This method requires caution and an understanding of electrical basics.

The essence of the method is to temporarily exclude the thermostat from the circuit and connect the wires coming from the network directly to the wire going to the compressor. If after such manipulation (with the refrigerator plugged in!) the motor starts and starts to freeze, it means that the compressor itself is working, and the problem is in thermostat.

However, this method has its limitations and risks:

• ⚡ Danger: Working with a voltage of 220V under load requires maximum concentration.
• ⏱ Time: You cannot keep the compressor turned on directly for longer than 15-20 minutes, as it may overheat without automatic shutdown.
• 🌡 Control: It is necessary to manually monitor the temperature so as not to freeze products into stone.

If, when closing the contacts, the compressor hums, but does not start, or knocks out plugs in the apartment, there is a problem lies deeper - in the starting relay or the engine itself. In this case, replacing the thermostat will not solve the problem.

Comparison of types of thermostats and fault table

In refrigerators Ariston different types of thermostats can be installed: mechanical (with a bellows and capillary tube) and electronic (resistance sensors). Mechanical ones are more maintainable and cheaper, but are subject to spring wear. Electronic ones are more accurate, but require checking the resistance in Ohms at different temperatures.

Below is a table that helps systematize symptoms and probable causes:

Sometimes there is a small hole on the body of a mechanical thermostat with an adjustment screw. Turning this screw half a turn can adjust the switch-on temperature by 1-2 degrees, which sometimes saves the situation without buying a new part.

Frequent errors when doing it yourself replacement

Even with correct diagnosis, beginners often make mistakes at the stage of installing a new part. The most common of these is incorrect positioning of the sensing tube. If it touches the walls of the chamber or other metal parts, the temperature readings will be distorted and the refrigerator will not work correctly.

The tightness of the tube insertion into the chamber is also often ignored. There should be a rubber seal where the capillary enters the inside of the refrigerator. If it is forgotten or damaged, warm, moist air from the room will constantly flow into the chamber. This will lead to the formation of ice and increased load on the compressor.

Another mistake is using the wrong analogue. Thermostats have different temperature response ranges. Installing a thermostat from the freezer compartment to the refrigerator compartment (or vice versa) will result in food either spoiling or freezing.

⚠️ Attention: The characteristics of thermostats may vary, even within the same brand. When purchasing a new part, be sure to check the markings (for example, K50, K59, TAM, etc.) with the number on your old part.

Remember that capillary tube length the new thermostat may differ from the original. Excess tubes should not be twisted into tight rings or bent - this may disrupt the circulation of gas inside the bellows. Carefully place the excess length with a snake in the free space behind the back wall.

Questions and answers (FAQ)

Is it possible to temporarily operate a refrigerator with a jumper instead of a thermostat?

Technically, you can start the motor by connecting the wires directly. However, you cannot operate the refrigerator in this mode all the time. The compressor will operate continuously, which will lead to overheating, freezing of the evaporator and spoilage of food. This solution is only valid for a few hours while you wait for a new part.

Where can you find the thermostat markings on an Ariston refrigerator?

The markings are applied to the metal body of the thermostat itself (for example, K59-L1234). To see it, you need to dismantle the regulator handle and remove the protective cover. The tag on the refrigerator itself shows only the model number of the unit, but not the part number of the thermostat.

Why doesn't the new thermostat click?

Some modern thermostats are silent or make a very quiet click. If the multimeter shows a change in resistance when the temperature of the tube changes, then the part is working, even if you do not hear a characteristic switching sound.

How often should the thermostat be changed?

The average service life of a mechanical thermostat is 7-10 years. Electronic sensors may last longer, but they are more sensitive to power surges. Scheduled replacement is not required, only in the event of a malfunction.

Does humidity in the kitchen affect the operation of the thermostat?

High humidity itself does not affect the internal mechanics of the thermostat, but can cause oxidation of external contacts and wiring, which will lead to interruptions in operation. It is important to monitor the serviceability of the door seal so that moisture does not condense inside the control unit.