The situation when an old refrigerator stops turning off and works without interruptions is one of the most common and critical problems in the operation of household appliances. This is not just the annoying hum of the compressor that prevents you from sleeping at night, but also a direct signal that the cooling system is operating in emergency mode. Homeowners often notice that their energy bills have skyrocketed and that the inside of their refrigerator or freezer is not at normal temperatures. Sometimes products begin to freeze, and in other cases, on the contrary, they deteriorate due to insufficient cold, despite the continuous operation of the motor.
Ignoring this symptom can lead to complete failure of an expensive component - the compressor, the replacement of which is often economically impractical for old equipment. Continuous operation the unit leads to overheating of the motor windings, burnout start relay and loss of refrigerant properties. Understanding the reasons for this behavior of the equipment will allow you to make the right decision: call a technician, try to fix the problem yourself, or think about buying a new model. In this article, we will analyze in detail the mechanical, electrical and physical reasons why your refrigerator “forgot” to rest.
It is important to understand that old models, even such proven brands as Atlant, Indesit or Stinol, have their own resource, calculated in years of service. Wear of seals, loss of elasticity of tubes and microscopic freon leaks are natural aging processes. However, if the equipment suddenly starts working non-stop, this always indicates a specific breakdown or violation of operating conditions that require immediate intervention.
Malfunctions of the thermostat and temperature sensors
The most likely reason for the endless operation of the compressor in old refrigerators is the failure of thermostat (thermostat). This device is responsible for opening the electrical circuit when the temperature inside the chamber reaches a set value. If the thermostat contacts stick in the closed position or the capillary tube loses sensitivity, the “brain” of the refrigerator simply does not receive a signal that the goal has been achieved. As a result, the motor continues to drive cold until the thermal protection relay operates or a breakdown occurs.
In modern models with a system No Frost or electronic control, the role of a mechanical thermostat is performed by temperature sensors (thermistors). Their resistance changes depending on the heating, and if the sensor “lies”, showing the control module that the chamber is warm, the compressor will work constantly. Diagnostics of such elements requires the use of a multimeter to measure resistance at different temperatures.
- 🔧 Sticking of contacts inside the mechanical thermostat, due to which the circuit does not open.
- 🌡️ Displacement or damage to the capillary tube of the thermostat, which should be in close contact with the evaporator.
- 📉 Incorrect readings of the electronic temperature sensor, transmitting a false signal to the control board.
- 🧊 Freezing of the sensor itself, which often happens when the defrosting system malfunctions.
⚠️ Attention: Before replacing the thermostat, be sure to disconnect the refrigerator from the power supply! Working with live electrical components is fatal. Also make sure that the new thermostat matches the parameters of your model, since the temperature response range may differ from one manufacturer to another.
If you notice that the refrigerator does not turn off, but it is too cold inside, and food freezes even at minimum settings, this is almost a hundred percent sign of a malfunction of the thermoregulatory system. In older models, carefully adjusting the screw on the thermostat itself sometimes helps, but this is a temporary solution. Completely replacing the thermostat or sensor is the only reliable way to solve the problem in the long term.
Refrigerant leak and circuit failure
The second most common reason why an old refrigerator hums but does not turn off is a leak freon (refrigerant). The principle of operation of the refrigerator is based on the circulation of gas, which takes heat from the chambers and releases it into the environment. If a microcrack appears in the circuit, the amount of refrigerant decreases. The compressor tries to compensate for the lack of cold by working to wear out, but it can no longer reach the set temperature.
Leaks often occur in the places where the tubes are soldered, in the foamed part of the housing (where the pipes approach the evaporator) or in the heat exchanger itself, located on the rear wall. In old refrigerators, the metal corrodes over time, especially if the equipment has been rarely washed or has been allowed to accumulate moisture for a long time. Also, the cause may be mechanical damage during inaccurate defrosting, when a sharp object touches the evaporator grille.
It is not always possible to visually diagnose a leak, since freon is a colorless and odorless gas. However, there are indirect signs that point specifically to this problem. If the compressor works, but does not turn off, and there is not enough cold, or it turns on for a short time and is turned off by the thermal relay, these are alarm bells.
- 🔍 Swelling of the back wall of the refrigerator or the appearance of yellow oily spots (oil leaks out along with freon).
- 🧊 Poor cooling the top of the refrigerator compartment during normal operation of the freezer (or vice versa).
- 🔊 Change in the sound of the compressor: it may become quieter or, conversely, louder and more intermittent.
- 🌡️ Heating of the side walls of the case is less than usual, since the condenser does not receive enough hot gas.
To eliminate the leak, you need to call a technician with professional equipment. It is necessary to find the location of the damage, seal it, evacuate the system and fill in a new volume of refrigerant strictly by weight. It is impossible to carry out this procedure independently without a vacuum pump and a pressure gauge station.
Why can’t you ignore working on freon?
If the refrigerator operates for a long time with a leak, moisture and air can enter the system through a leaky place. This leads to the formation of acids inside the circuit, which corrode the windings of the compressor from the inside, causing its rapid demise.
Problems with sealing rubber bands and heat loss
Often the reason for continuous operation lies not in the “insides” of the unit, but in its ability to retain cold. The rubber seals on the doors of an old refrigerator lose their elasticity over time, crack and become deformed. Through the resulting cracks, warm air from the room constantly enters the chamber. Sensors detect an increase in temperature and command the compressor to work harder to compensate for the heat gain.
You can check the tightness of the door using a simple folk method. Take a regular sheet of paper, clamp it with the refrigerator door and try to pull it out. If the sheet is removed easily, without resistance, it means that the fit is broken in this place. Particular attention should be paid to the corners of the door and places near the hinges, where wear occurs most quickly.
In addition, heat loss can occur due to door misalignment. If the refrigerator is not level or the hinges have weakened over time, the door may not close completely on its own. In older models with magnetic seals, contamination of the rubber itself with grease and dirt also reduces its magnetic properties and tightness.
⚠️ Attention: Do not try to stretch or heat the seal with a hairdryer if there are visible breaks on it. This will not restore the rubber structure. In case of physical damage, only complete replacement of the sealing tape with a new one helps.
☑️ Checking the door tightness
Freezing and malfunctions of the defrost system
For refrigerators with the system No Frost or drip defrosting, timely removal of moisture is critical. If the drainage hole in the refrigerator compartment becomes clogged with crumbs, ice or mold, the water does not go into the pan, but freezes, forming an ice plug. Over time, ice build-up can reach the temperature sensor or even block the operation of the damper that supplies cold air.
In systems No Frost there is a special defrost cycle, for which the heating element (heating element), defrost timer and defrost sensor are responsible. If any of these elements fail, a “coat” of ice builds up on the evaporator, hidden behind the back panel of the freezer. This ice mass blocks air circulation. The fan is humming, the compressor is working non-stop, trying to cool the chambers, but the cold simply does not reach the food.
You can diagnose evaporator freezing by paying attention to the characteristic crackling or creaking noise when the refrigerator is operating, as well as the fact that the back wall inside the chamber is covered with an uneven layer of frost or ice. In this case, complete defrosting of the unit is required (at least 24 hours with the doors open) and checking the defrost circuit.
- ❄️ Failure of the defrost heating element, which stops heating and melting ice on the evaporator.
- ⏱️ Malfunction of the defrost timer, which does not switches the refrigerator to defrost mode.
- 🌡️ Breakdown of the defrost sensor, which “does not see” that the evaporator has warmed up and does not allow the compressor to start (or vice versa).
- 💧 Clogged drainage hole, leading to water flow and the formation of ice jam.
Often owners, noticing ice, simply chop it off with a knife. This is strictly forbidden, as you can damage the evaporator tubes, which will lead to a freon leak, which we discussed above. The best solution is to defrost and find the reason why the system has stopped coping on its own.
Technical characteristics of the compressor and start relay
The heart of the refrigerator - the compressor - can also be the source of the problem. In older models, the starting relay often fails. This device provides an impulse to start the engine. If the relay is stuck or burned out, the compressor may hum, trying to start, but not start, or work intermittently, not developing the necessary power to create pressure in the system.
In addition, over time, the compressor loses its performance. The piston group wears out, the valves no longer hold pressure. The motor continues to run, creating the appearance of activity, but the freon does not circulate at the required speed. As a result, the temperature in the chambers does not drop, and the thermostat does not give a command to stop.
It is important to distinguish between the normal noise of a running compressor and the sound of an overloaded motor. If the unit vibrates more than usual, gets very hot (more than 70-80 degrees) or makes a metallic clanging sound, these are signs of its imminent demise. Non-stop operation of such a compressor will finish it off in a matter of days.
Comparative table of symptoms and causes
To make it easier for you to navigate the variety of possible breakdowns, we have prepared a summary table. It will help to compare the observed symptoms with the most probable causes.
| Symptom | Probable cause | Nature of compressor operation | Temperature in the chambers |
|---|---|---|---|
| The refrigerator does not turn off, it is very cold inside | The thermostat is faulty (contacts are stuck) | Works continuously, without pauses | Below normal, food freezes |
| It hums, but there is little or no cold no at all | Freon leak or capillary blockage | Works for a long time, there may be relay clicks | Above normal, food spoils |
| Works without stopping, there is ice on the walls | Malfunction of the defrost system (No Frost) | Constant hum, cracking is possible | Uneven, depends on the airflow |
| Hums and turns off after 1-2 minutes | Start relay or the compressor itself | Short operating cycles with a click | The temperature does not change |
When analyzing the behavior of your equipment, pay attention to a combination of factors. The mere fact of continuous operation only indicates that the cooling cycle is not complete. But if you add to this the temperature inside, the presence of ice and the nature of the sounds, the picture becomes much clearer.
Frequently asked questions and answers (FAQ)
Is it possible to leave an old refrigerator to work continuously overnight?
It is strictly not recommended. If the refrigerator does not turn off, it means it is operating in emergency mode. If you leave it unattended overnight, you risk causing a fire due to overheating of the wiring or compressor, as well as completely destroying the equipment. It is better to turn it off from the network before the technician arrives.
Why did the refrigerator start working constantly after defrosting?
Most likely, during the defrosting process the seal was damaged or you damaged the evaporator tube with a sharp object, which led to a freon leak. It is also possible that water got into the electrical contacts of the thermostat or sensor, causing a short circuit or incorrect operation.
How long should the compressor of an old refrigerator normally run?
Under normal conditions, the operating cycle is approximately 15-20 minutes, followed by a pause of 30-40 minutes. That is, the refrigerator should operate no more than 30-40% of the total time. If it works 80-90% of the time or without stopping, this is a malfunction.
Does the temperature in the room affect the operation of the refrigerator?
Yes, it does directly. If the refrigerator is located near a radiator, stove, or in direct sun, it is more difficult for it to give off heat. The compressor will be forced to work longer. It is also not recommended to operate old models at room temperatures below +10°C or above +32°C.
What to do if the refrigerator is old and repairs are more expensive than a new model?
If diagnostics showed the need to replace the compressor or complex sealing of the circuit in the foamed part, and the age of the equipment exceeds 10-12 years, it is more economically feasible to purchase a new unit. Repairing an old “suitcase” can cost 60-70% of the cost of a new budget model.
How to extend the life of an old refrigerator?
Regularly wash the condenser (grid at the back) from dust, check the tightness of the door and do not put hot foods inside. These simple actions reduce the load on the compressor.
To summarize, we can say that continuous operation of the refrigerator is always a “cry for help” from your equipment. Whether it's a simple thermostat replacement or a complex repair of the refrigerant circulation system, you can't hesitate to solve the problem. Timely contact with specialists or competent self-diagnosis will help save food, money and nerves.