The situation when the refrigerator stops cooling often confuses the owner, especially if the unit is full of products, and it is impossible to call a technician right now. One of the most common causes of failure is the failure of the thermostat (thermostat), which stops closing the circuit and supplying power to the compressor. In such cases, it becomes necessary to start the motor directly to check its performance or temporarily store products until the part is replaced.
However, it is worth immediately defining the limits of what is permissible: direct starting of the engine without a control element is an emergency mode of operation, which is not intended for long-term operation. Atlant refrigerators, Indesit or LG have their own design features, but the principle of supplying voltage to the motor windings is similar. Incorrect actions can lead not only to compressor failure, but also to a wiring fire.
Before you begin any manipulations with the electrical part, you must clearly understand what you are doing and why. This procedure is primarily intended diagnostics: you need to find out whether the compressor itself is alive or the problem lies deeper. If the engine starts and starts humming, creating cold, then the problem is really in the temperature sensor, and replacing it will solve the issue.
⚠️ Attention: All work on opening the electrical panel and manipulating 220-volt wires is carried out only when the device is disconnected from the network. Power supply is carried out exclusively at the final stage of testing and only by qualified personnel or persons with appropriate electrical installation skills.
To understand the process, it is necessary to understand what role the thermostat plays in the overall circuit. This small device serves as the “brain” that reads the temperature inside the chamber and opens or closes the electrical circuit. When you exclude it from operation, you take control over yourself, which requires constant monitoring.
The principle of operation and the role of the thermostat in the circuit
The thermostat is a simple electromechanical device that breaks the phase wire when the set temperature is reached. In normal mode, the current passes through the thermostat contacts, then through the thermal protection relay (tablet) and enters the compressor starting relay. Without a thermostat, the circuit opens and the engine does not receive a starting impulse, remaining at rest.
Structurally, the connection diagram looks sequential. The phase from the socket goes to one contact of the thermostat, and a controlled signal comes out from the other. If this element is faulty (the contacts have oxidized, the bellows has lost its seal, or the capillary tube has burst), the circuit remains open forever. This is why electricians often use the "jumper" method to test the motor, eliminating the sensor from the equation.
It is important to understand the difference between single-prong and two-prong thermostats. In modern models, a second contact is often found, which is responsible for the lighting bulb or, in more complex systems, for an error signal to the control board. To start the motor, it is the power contact that breaks the phase that is important to us.
Technical details of the bellows operation
Inside the thermostat there is a bellows - a corrugated tube filled with refrigerant. When heated, the gas expands and opens the contacts; when cooled, it contracts, closing them. If the tube bursts, the gas escapes and the contacts never close, requiring replacement of the assembly.
Ignoring the role of the protective thermal relay when creating a bypass circuit can be fatal. This device stands between the thermostat and the engine start relay and protects the windings from overheating. When connecting directly, it is important not to lose this element of protection, otherwise the motor will burn out at the first overheat.
Necessary tools and safety measures
To carry out a successful and safe starting procedure, you will need a minimum set of tools that a home mechanic usually has. The quality of the tools directly affects safety, so using damaged or handicraft devices is strictly not recommended.
You will need:
- 🔧 Screwdrivers (Phillips and flathead) for removing the casing and terminals.
- ✂️ Side cutters or wire cutters for cutting insulation when necessary.
- 🧤 Dielectric gloves to protect hands when working under voltage.
- 💡 Indicator screwdriver or multimeter to check the presence of a phase.
- 🔌 Insulating tape or terminal blocks for connecting wires.
Particular attention should be paid to the condition of the wire insulation. Old refrigerators often have dry insulation that cracks at the slightest bend. Before connecting, carefully inspect the wires leading to the compressor. If bare areas of copper are visible, they must be insulated.
The work place should be dry and well lit. Do not allow electrical contacts to get wet. If the kitchen floor is wet or you are standing in a puddle of water, work cannot be carried out. Also make sure that the refrigerator plug is easily accessible for immediate removal from the socket in case of sparking or smoke.
The use of low-quality insulating materials can lead to a short circuit. Regular tape or cling film will not work - only specialized PVC tape or heat shrink.
Step-by-step instructions for connecting a compressor
The process of starting the engine bypassing the thermostat requires sequential steps. Any deviation from the algorithm can lead to an incorrect connection, which can lead to failure of the starting relay or the motor itself.
Action algorithm:
- Disconnect the refrigerator from the power supply. This is the first and mandatory rule.
- Remove the protective cover at the bottom of the rear wall (or top, depending on the model) where the compressor is located.
- Find the thermostat. It is usually located inside the chamber, but its electrical contacts may be routed outside or located in the same compartment with the motor.
- Locate the wires going to the thermostat. As a rule, there are two of them (incoming phase and outgoing phase for protection).
- Connect these two wires directly, bypassing the thermostat contacts. Use twisting followed by soldering or a reliable terminal block.
- Carefully insulate the connection point.
- Plug in the refrigerator.
If after turning on you hear a characteristic click of the start relay and the hum of the motor, which after a few seconds turns into a smooth hum, it means the compressor OK The system will start to get cold. At this moment, it is necessary to control the temperature, since now the refrigerator will work continuously until you break the circuit again.
☑️ Check before turning on
In some models, for example, in old ones ZIL or Ocean, the circuit may also include a button quick freezing. If there is one, make sure it is not blocking the circuit either. In modern systems with electronic control (No Frost with a board), a simple mechanical bypass of the thermostat may not work, since the temperature signal goes to the processor.
⚠️ Attention: When connected directly, the refrigerator loses the ability to automatically turn off. This means that the evaporator may become coated with ice, and the food in the main chamber may freeze. Do not leave such a refrigerator unattended for a long time.
Diagnostics of faults during startup
Even with the correct connection of the wires, the refrigerator may not work. This indicates that the problem is not only in the thermostat, or that the thermostat itself was working properly, and the reason lies in another unit. It is important to be able to read the “symptoms” that the unit gives.
If after turning on the power you hear a quiet hum lasting 1-2 seconds, followed by a click and silence, this is a sign of a faulty start relay or a jammed compressor. Attempts at repeated start (multiple starts) in this case can finally finish off the engine. The relay could “stick” or burn out, failing to start the rotor.
The table below shows the main symptoms and their probable causes:
| Symptom | Probable cause | Action |
|---|---|---|
| The engine hums, but does not start | The starting relay is faulty or the piston is jammed | Replace the relay, check compressor |
| Complete silence, no light | Open circuit, burned out wiring or socket | Check the voltage with a multimeter |
| There is a hum, no cold | Leakage freon or clogged capillary | A technician with equipment is required |
| Strong vibration and knocking | Destruction of the compressor suspension | Replacement of the compressor |
The situation when the engine starts, runs, but does not cool down deserves special attention. In this case, bypassing the thermostat was successful, the engine is alive, but the tightness of the circuit is broken. Freon could have evaporated through a microcrack. There is no point in operating such a refrigerator - it will consume electricity but not produce cold.
It is also worth checking the integrity of the motor windings. To do this, you will need a multimeter in resistance measurement mode. The resistance between the common winding and the starting winding, as well as between the common and working windings, must be within the normal range (usually from 10 to 30 Ohms). Infinite resistance will indicate a break in the winding.
Risks and limitations of temporary operation
Using a refrigerator without a thermostat is always a compromise between the need to preserve food and the risk of losing expensive equipment. Understanding these risks will help you make an informed decision.
The main danger is the lack of a defrost cycle. In normal mode, when the thermostat opens the circuit, the temperature in the evaporator rises, and the ice has time to thaw. With constant operation of the compressor, moisture from the air turns into an ice monolith. This creates a load on the engine and worsens heat transfer.
In addition, the compressor life is designed for cyclic operation. Constant work without stopping leads to overheating of the oil, loss of its lubricating properties and, as a result, accelerated wear of rubbing parts. The motor can work for days, but its service life will be reduced significantly.
⚠️ Attention: In models with the No Frost system, constant operation of the fan and compressor without defrosting cycles will lead to rapid freezing of the air ducts. This can cause mechanical damage to the fan blades due to ice.
Another aspect is the quality of the products. In the main chamber, the temperature may drop below zero. Vegetables and fruits will freeze, losing their structure, and dairy products may separate. Therefore, when operating in emergency mode, it is better to transfer the products into containers or temporarily reduce the amount of stored supplies.
Frequently asked questions and answers (FAQ)
Is it possible to leave the refrigerator running without a thermostat for a week?
It is strictly not recommended. A week of continuous operation will lead to severe freezing of the evaporator, possible failure of the compressor due to overheating and spoilage of food in the main chamber. This is an emergency measure for a few hours, maximum for a day, until the spare part is delivered.
Which thermostat should I buy as a replacement?
Thermostats are not universal. You need to know the exact model of your refrigerator or, better yet, the markings of the old thermostat (for example, TAM 133, K-59, TAM-112). They differ in the length of the capillary tube, the on/off temperature and the presence of additional contacts.
Why does the refrigerator not turn off after replacing the thermostat?
Perhaps the new thermostat has a different temperature range or the capillary tube is installed incorrectly (not deep enough into the evaporator). Also, the cause may be a freon leak: the sensor cannot reach the desired temperature, since there is simply no cold, and the motor turns constantly.
Is it dangerous to touch the wires when the refrigerator is on?
Yes, it is deadly. The voltage of 220 Volts is not always visually noticeable, but an electric shock can be fatal. Make all connections only with the plug removed from the socket. To check the voltage, use only working tools with dielectric insulation.
To summarize, it is worth saying that starting a refrigerator without a thermostat is an effective diagnostic method, but a bad strategy for life. If you are sure that the motor is working, try to purchase and install a new temperature sensor as soon as possible. This will extend the life of your refrigerator and keep your home safer.