Thermostat in the Indesit refrigerator: device, principle of operation and fault diagnosis

The thermostat is the “brain” of the refrigerator Indesit, which is responsible for maintaining the set temperature. Without it, the unit will either stop freezing or start working without stopping, risking burning out. In this article we will figure out how the thermostat works in models Indesit, on what principle it controls the compressor and what to do if it fails.

You will find out what signals indicate a thermostat malfunction, how to check it with a multimeter and whether you can repair it yourself. We will also compare mechanical and electronic thermostats that are installed in refrigerators Indesit of different generations, and give recommendations on choosing a replacement.

If your refrigerator suddenly stops turning off, freezes too much or, conversely, does not cool, the problem most likely lies in the thermostat. Below you will find step-by-step instructions that will help you diagnose a breakdown without calling a technician.

What is a thermostat and why is it needed in a refrigerator?

A thermostat (or thermostat) is a device that measures the temperature inside the refrigerator or freezer and controls the operation of the compressor. Its main task is to maintain the temperature regime specified by the user, turning the motor on and off as needed.

In refrigerators Indesit two types of thermostats are used:

• 🔧 Mechanical — with a manual regulator (wheel or switch) and siphon tube filled with refrigerant. Installed in budget and mid-range models (for example, Indesit BIA 18, Indesit ST 167).
• 📱 Electronic - with a digital sensor and microcontroller. Found in modern refrigerators with a display (Indesit ITF 118, Indesit EF 18).

When the temperature in the chamber rises above the set value, the thermostat closes the contacts and starts the compressor. As soon as the air cools to the desired level, the circuit opens and the motor turns off. This cycle is repeated continuously, ensuring stable storage of products.

Thermostat design in the Indesit refrigerator

The design of the thermostat depends on its type, but in both cases the operating principle is based on the physical properties of gases and liquids. Let's look at the device of each type in more detail.

Mechanical thermostat

Consists of the following key elements:

• 🔄 Siphon tube - a thin capillary tube filled with freon or other refrigerant. One end of it is attached to the evaporator, the other to the thermostat membrane.
• 📏 Membrane - a flexible plate that responds to the pressure of the refrigerant in the tube. When heated, the gas expands, the pressure. grows, and the membrane bends.
• ⚙️ Contact group - mechanical contacts that close/open under the action of the membrane.
• 🎛️ Adjustment knob - allows the user to set the desired temperature (usually from 1 to 7, where 1 is the most warm, 7 - the coldest).

When the temperature in the chamber rises, the refrigerant in the tube expands, the pressure rises, and the membrane closes the contacts, turning on the compressor. When cooling, the process occurs in the reverse order.

Electronic. thermostat

Modern models Indesit instead of mechanics are used:

• 🌡️ Thermistor —a semiconductor sensor, the resistance of which varies depending on the temperature.
• 🖥️ Microcontroller —analyzes signals from the sensor and controls the relay compressor.
• 📊 Display - displays the current temperature and allows you to more accurately adjust the mode (for example, in Indesit ITF 118 you can set the temperature in steps of 1°C).

Electronic thermostats are more accurate than mechanical thermostats, but are more sensitive to voltage fluctuations. During power surges, they can reset settings or fail.

What does the thermostat look like in an Indesit refrigerator?

A mechanical thermostat is usually a plastic box the size of a palm, to which a thin capillary tube fits. It is attached to the evaporator (the back wall of the refrigerator. cameras). The electronic thermostat can be built into the control board or look like a small module with connectors for sensors.

Signs of a thermostat malfunction

If the thermostat is faulty, the refrigerator Indesit here are the main symptoms that should alert you:

• ❄️ The compressor runs without stopping — the motor does not turn off even when the minimum temperature is reached. This means that the thermostat does not open the contacts.
• 🔥 The refrigerator does not turns on —if the thermostat does not close the circuit, the compressor does not start and the chamber stops cooling.
• ❓ Temperature does not match the settings —for example, you set mode “3”, but the chamber is too cold or, conversely, warm.
• 🔊 Clicks without starting the motor —if you hear characteristic sounds of the relay operating, but the compressor does not start, the problem may be in the thermostat contacts.
• 💧 Freezing of the back wall —if the thermostat is faulty, the compressor can run for too long, which leads to ice on the evaporator.

In Indesit refrigerators with the No Frost system, a faulty thermostat often causes the fan to constantly work, which leads to to icing of air ducts and deterioration of cooling.

If you notice at least one of these signs, first check the thermostat. In 70% of cases, it is to blame for the unstable operation of the refrigerator.

⚠️ Attention: Before diagnosing, unplug the refrigerator and wait until the compressor cools down. (10–15 minutes). Working under voltage is dangerous!

How to check the thermostat of an Indesit refrigerator

You can carry out diagnostics yourself using a multimeter. We will consider both options - for a mechanical and electronic thermostat.

Checking a mechanical thermostat

You will need:

• 🔧 Screwdriver (Phillips or flathead).
• 📊 Multimeter (in continuity or resistance measurement mode).
• 🧊 Container with cold water (to simulate low temperature).

Step-by-step instructions:

1. Disconnect the refrigerator from the power supply.
2. Remove the thermostat protective cover (usually it is located inside the refrigerator compartment, next to the temperature control knob).
3. Disconnect the wires from the thermostat terminals (take a photo of their location, so as not to get confused during reassembly).
4. Switch the multimeter to the continuity mode and connect the probes to the contacts 3 and 4 (usually they are marked).
5. If the contacts are closed, the thermostat is working. If not, it is needed. replace.
6. For additional testing, place the siphon tube in cold water (for example, +5°C). After 2-3 minutes, the contacts should open. If this does not happen, the thermostat is faulty.

Disconnect the refrigerator from the power supply

Remove the thermostat casing

Disconnect the wires (take a photo of the circuit)

Ring contacts 3 and 4 with a multimeter

Place the tube in cold water and check the opening-->

Checking the electronic thermostat

Electronic thermostats are more difficult to diagnose, since they are integrated into the control board. You will need:

1. Unplug the refrigerator and remove the back cover (in some models Indesit the board is located under the top panel).
2. Find the thermistor - it looks like a small cylinder with two wires attached to the evaporator.
3. Measure its resistance multimeter. At room temperature (~20°C) it should be in the range 5–7 kOhm.
4. Place the sensor in cold water (for example, +5°C) and measure the resistance again - it should increase to 20–30 kOhm.
5. If the resistance does not change or is zero/infinity, the thermistor is faulty.

If the thermistor is working, but the refrigerator is not working correctly, the problem may lie in the control board. In this case, it is better to contact a specialist.

⚠️ Attention: In refrigerators Indesit with electronic control (for example, Indesit ITF 118), when replacing the thermostat, it may be necessary to reflash the board. It is impossible to do this on your own - you need a special programmer.

Table: Comparison of mechanical and electronic thermostats

As can be seen from the table, electronic thermostats are more accurate and durable, but their repair is more expensive. Mechanical ones are easier to maintain, but less stable.

How to replace the thermostat in an Indesit refrigerator

If diagnostics showed that the thermostat is faulty, it needs to be replaced. In most cases, this can be done independently, without the help of a specialist.

Tools and materials

• 🔧 Screwdriver (Phillips or flat, depending on the model).
• 🔌 New thermostat (must match the refrigerator model).
• 📸 Phone or camera (to take a photo of the connection diagram).
• 🧴 Thermal paste (if you need to replace the thermistor in electronic models).

Step-by-step instructions for a mechanical thermostat

1. Unplug the refrigerator and defrost it.
2. Remove the temperature control knob (usually it is secured with latches or a screw).
3. Unscrew the mounting screws and remove the thermostat casing.
4. Disconnect the wires from the terminals (be sure to photograph their location!).
5. Carefully remove the capillary tube from the mounts on the evaporator.
6. Install a new thermostat, connect the wires according to the diagram and secure the tube.
7. Assemble the casing, install the handle and turn on the refrigerator.

After replacement Let the refrigerator run for 2-3 hours, then check the temperature in the compartment. If everything is done correctly, the compressor should turn off periodically.

Replacing the electronic thermostat

In electronically controlled refrigerators (for example, Indesit EF 18) the process is more complicated:

1. Turn off the refrigerator and remove the back cover.
2. Find the control board and thermistor (usually it is attached to the evaporator).
3. Disconnect the sensor connector from the board.
4. Install a new thermistor, applying thermal paste to it for better contact.
5. Connect the connector back and reassemble refrigerator.

⚠️ Attention: In some models Indesit after replacing the electronic thermostat, errors must be reset through the service menu. To do this, press and hold the button Super Cool (or Super Freeze) for 10 seconds. If the indicators on the panel are blinking, contact the service center.

Common mistakes when replacing a thermostat

Even with the apparent simplicity of the procedure, many make mistakes that lead to repeated breakdowns. Here are the most common of them:

• 🔌 Incorrect connection of wires - if you mix up the terminals, the refrigerator will either not turn on or will work continuously. Always take photographs of the original circuit!
• 🧊 Damage to the capillary tube - if dismantled carelessly, it can be bent or torn. This will lead to refrigerant leakage and incorrect operation of the thermostat.
• 🔧 Using an incompatible thermostat - even if it looks similar, the internal characteristics (temperature range, resistance) may not be suitable. Always check the model by catalog number.
• 💡 Ignoring checks after replacement —if you do not test the refrigerator within 24 hours, you can miss hidden defects (for example, freon leakage).

To avoid these errors, follow the instructions and take your time. If you are not confident in your abilities, it is better to contact a specialist - it is cheaper than repairing the consequences of incorrect replacement.

FAQ: Frequently asked questions about thermostats in Indesit refrigerators

Can the thermostat be repaired or just replaced?

Mechanical thermostats cannot be repaired - they can only be replaced. In some cases, electronic ones can be restored (for example, by replacing the thermistor or re-soldering the contacts), but this requires special equipment and skills.

Which thermostat is better - mechanical or electronic?

Electronic thermostats are more accurate and reliable, but more expensive to repair. Mechanical ones are simpler and cheaper, but less stable. The choice depends on the model of the refrigerator and your budget.

Why does the Indesit refrigerator not turn off after replacing the thermostat?

Possible reasons:

• The wires are not connected correctly.
• The new thermostat is defective.
• Refrigerant leak (refill required).
• Failure of the control board (in electronic models).

Check the connection and, if the problem persists, contact service.

How much does it cost to replace the thermostat at a service center?

The price depends on the model of the refrigerator and the type of thermostat:

• Mechanical: 1,500–3,000 RUR (spare part + labor).
• Electronic: 3,000–6,000 RUR (board replacement may be required).

In some cases, it is cheaper to buy a new refrigerator if repairs cost half of its cost.

Is it possible to temporarily operate a refrigerator without a thermostat?

No, this is dangerous! Without a thermostat, the compressor will run continuously and may overheat. If the thermostat is broken, turn off the refrigerator before replacing it.