The situation when a a thick coat of ice, and vegetables in the lower compartment turn into ice blocks, is familiar to many owners of older equipment. If your an old refrigerator is very cold, this is not just an annoying little thing, but a signal that a failure has occurred in the thermoregulation system or the tightness of the circuit. Ignoring the problem can lead to food spoilage, excessive energy consumption and, ultimately, to expensive compressor repairs.
Unlike modern models with a system No Frost and electronic control, in old units a mechanical thermostat is responsible for maintaining the temperature. Its operation is based on simple physical principles of expansion and compression of gas or liquid inside a bellows. Over time, these mechanisms wear out, lose calibration or fail, which leads to continuous operation of the motor-compressor. Understanding why why this happens will help you save time and money.
Next we will analyze in detail all the possible reasons, from banal adjustment of the regulator knob to complex technical malfunctions. You will learn how to carry out initial diagnostics yourself and understand when you really need to call a specialist. It is important to act sequentially, checking each component in order to accurately identify the source of the problem.
⚠️ Attention: Before starting any diagnostic work or replacing parts, be sure to disconnect the refrigerator from the electrical network. Working with electrical appliances under voltage is dangerous to life!
Malfunctions of the thermostat and thermostat
The most common reason why a refrigerator starts to work non-stop and freezes excessively is failure thermostat. In older models, this is a mechanical device that closes and opens the electrical circuit of the compressor depending on the temperature in the chamber. If the contacts inside the thermostat “stick” in the closed position or the sensitive tube depressurizes, the compressor receives a signal to work constantly, without turning off even when the specified minimum is reached.
Diagnostics of the thermostat often requires testing the contacts with a multimeter, but there are also indirect signs. If the compressor continues to hum when you turn the control knob to the “Off” or “0” position, the problem almost certainly lies in this unit. It is also worth paying attention to the length of the rod - if it is too long or short for your model, the sensor will read the temperature incorrectly.
- 🔧 Sticking of contacts: Soot has formed inside the mechanism, and the chain does not break.
- 🌡️ Freon leak from the bellows: The pressure inside the sensor has dropped, and it “thinks” that it is in the chamber heat.
- ⚙️ Failed calibration: The mechanism has become loose from vibration and has stopped responding accurately to changes.
- 🔌 Wiring fault: Short circuit in the control circuit bypasses the regulator.
How to check the thermostat without a multimeter?
Remove the terminals from the thermostat and connect them directly to each other (close the circuit). If the compressor starts working after being plugged in, then the problem is most likely in the thermostat. However, this method does not provide a 100% guarantee and requires caution.
Replacing a thermostat is a procedure accessible to a home craftsman, but requires care. It is important to install a new sensor with similar parameters, otherwise the operating modes may go wrong. Remember that incorrect installation of the capillary tube can lead to the refrigerator starting to freeze too much again or, conversely, stopping gaining cold.
Problems with the sealing rubber on the door
It would seem, what is the connection between the rubber gasket and the fact that the refrigerator very freezing? The answer lies in the logic of the automation. If the rubber seal on the door is worn out, cracked, or simply does not fit tightly to the body, warm air from the room constantly enters the chamber. Temperature sensors record an increase in degrees and instruct the compressor to work harder to compensate for the heat gain.
As a result, the motor wears out, trying to “catch up” with the temperature, which leads to freezing of food and the formation of a huge amount of ice on the back wall. This is especially common in older models, where the rubber has lost its elasticity over the years of use and simply “petrified”. Visually this may not always be noticeable, so a thorough check is required.
☑️ Checking the door tightness
There is a simple and effective way to check the tightness, known as the “paper test”. Take a regular sheet of office paper, clamp it with the refrigerator door and try to pull it out. If the sheet is removed easily and without resistance in different places around the perimeter, it means the seal is broken. In places where the paper is clamped tightly, there is no leakage, but where it slides freely, the seal needs to be replaced or the hinges adjusted.
Sometimes the problem is solved by simply lubricating it with silicone or heating it with a hairdryer, if the rubber is simply deformed but not torn. However, in most cases, older refrigerators require a full replacing the sealing collar. The new rubber will ensure proper insulation, and the compressor will be able to operate normally, turning on only when necessary.
Refrigerant leakage and compressor operation
One of the most insidious reasons why a refrigerator starts working continuously is a leak. freon (refrigerant). It would seem that logic dictates that if there is a shortage of gas, the cold should disappear. However, in systems with a mechanical thermostat, the opposite happens: the temperature sensor located inside the chamber cannot detect the achievement of the required minimum due to low heat transfer efficiency. As a result, he does not give the command to turn off the motor.
The compressor hums for days on end, trying to raise the temperature, but due to the lack of working fluid in the system, this is impossible. As a result, the evaporator may become overgrown with an uneven layer of frost (often only at the beginning of the circuit), and in the main chamber the temperature may be higher than normal, although the motor is working at its limit. This condition is extremely dangerous for the compressor itself, which can burn out from overheating.
| Symptom | Cause | Action |
|---|---|---|
| The compressor is hot | Continuous operation without stops | Disconnect from the network, call a technician |
| Frost only at the entrance to the evaporator | Lack of freon in the system | Search for leaks and refuel |
| The temperature in the chamber is higher +5°C | Heat transfer disturbance | Diagnostics of the cooling system |
| Gurgling or hissing is heard | Gas escaping through a micro-hole | Urgent repair circuit |
It is impossible to eliminate a freon leak on your own, since this requires special equipment: a vacuum pump, a pressure gauge station and a supply of refrigerant. In addition, the location of the leak is often in the foamed part of the body or in sealed tubes, which requires a professional approach. If you notice that the refrigerator it is making a lot of noise does not turn off, and the food spoils, most likely it is a leak.
Incorrect setting and position of the regulator
Before sounding the alarm and looking for complex technical faults, it is worth checking trivial things. Often users, especially in the hot season or after a large load of food, accidentally or intentionally move the thermostat knob to position maximum cold. In older models, the scale may not be digitized, but indicated by marks or the words “Min” and “Max”. If the knob is at maximum, the refrigerator will freeze until it stops.
It is also worth considering seasonality. In winter, when the room is cool, setting the maximum power can lead to freezing. In the summer, on the other hand, more intensive operation may be required, but even then the "maximum" mode is usually used only for quick freezing, and not for continuous use.
- ❄️ Super Freeze position: Many older models have a separate button or position for quick freezing, which disables the automatic shutdown. Check if you forgot to turn it off.
- 🌡️ The calibration screw pair has shifted: There is a screw inside the regulator handle that could move when turned too hard, changing the temperature range.
- 📉 Misunderstanding of the scale: Make sure that the number “5” or “7” on your refrigerator does not mean the lowest temperature, but the operating mode (check the instructions).
It is recommended to set the regulator to the middle position (usually this is the number 3 out of 5 or 4 out of 7) and observe the operation of the unit during the day. If the problem disappears, then the equipment is working properly, and it was just a matter of settings. If, even at minimum, the refrigerator continues to work non-stop and gets very cold, you will have to look deeper for the reason.
Contamination of the system and problems with defrosting
In old refrigerators, especially in models with a crying evaporator, the condition of the defrosting system is critically important. If the drainage hole through which the melt water goes into the tray above the compressor becomes clogged with crumbs, ice or mold, the water will begin to accumulate at the bottom of the chamber and freeze. Over time, the layer of ice grows, blocking the heat exchange between the evaporator and the air in the chamber.
The thermostat, sensing that the temperature in the main part of the chamber does not drop to normal (due to an ice coat on the evaporator), causes the compressor to work longer and more intensely. As a result, the walls become covered with a thick layer of ice, and food in the immediate vicinity of the back wall freezes tightly. This is a classic situation when the refrigerator is very cold locally, but has difficulty maintaining the overall temperature.
The solution to the problem often lies in regular maintenance. It is necessary to completely defrost the refrigerator at least once every 6 months. During this procedure, it is important to carefully clean the drainage hole with warm water or a soft blower. Using sharp objects to chip ice is prohibited, as you can damage the evaporator tubes, which will lead to freon leakage.
⚠️ Attention: Never use a hair dryer to speed up defrosting or sharp knives to chip ice! A sudden temperature change or mechanical damage to the evaporator tubes will completely damage the refrigerator.
It is also worth checking the condition of the defrost heater (if the model assumes its presence) and the defrost sensor. If the heating element is burned out, the ice will not melt automatically, which will lead to the “snowball” effect described above and continuous operation of the motor.
Wear of other elements of the cooling system
In addition to the main components, the operation of the refrigerator is also affected by other parts that wear out over time. For example, loss of thermal insulation properties of polyurethane foam in the walls of the housing. In very old models (Soviet-made or early imported), the insulation could have dried out or become saturated with moisture, which is why the cold is less well retained inside. The compressor is forced to turn on more often to compensate for heat inflows.
Another element is a start-up relay. If it is faulty, the compressor may work intermittently, hum, but not develop the required power, or, conversely, not turn off on time. Although more often the relay causes the refrigerator to stop turning on, its incorrect operation can also affect the cyclicity.
It is also worth mentioning the blockage capillary tube. If an ice or oil plug forms in the freon circulation system, the refrigerant cannot circulate normally. This causes pressure surges and incorrect operation of the entire system, which is often perceived by the user as chaotic behavior of the equipment: sometimes it freezes a lot, sometimes it doesn’t freeze at all.
When you need to call a technician
Independent repair of the refrigerator is only possible if you replace the thermostat, seal or clean the drainage. All other manipulations related to the sealed circuit (filling with freon, soldering pipes, replacing the compressor) require a license, special tools and skills. An attempt to independently climb into the “insides” of the cooling system can lead to injuries and final breakdown of the equipment.
Calling a specialist is necessary if:
- 🛠️ You find a freon leak (oil stains, smell).
- 🔊 The compressor makes uncharacteristic sounds (knock, rattle) or gets very hot.
- ❄️ The refrigerator works around the clock, but the temperature in the chamber does not drop below +10°C.
- 💡 After replacing the thermostat, the problem did not disappear.
Professional diagnostics are not so expensive, but it allows accurately determine whether it is worth repairing an old refrigerator or whether it is more economically feasible to purchase a new, more energy-efficient unit. Modern models consume significantly less electricity, which pays for their cost in the long run.
Is it possible to repair an old Soviet refrigerator?
Yes, the design of Soviet refrigerators (Biryusa, ZIL, Saratov) is very simple and repairable. Spare parts are still produced for them: TAM thermostats, seals, starting relays. However, it is worth considering their high energy consumption and wear of the main body. If the circuit is broken (the tube inside the cabinet has rotted), repairs are often unprofitable.
Why did the refrigerator start to freeze even more after defrosting?
Perhaps you set the regulator to maximum during defrosting and forgot to return it to the operating position. The cause may also be residual moisture in the drainage system, which has frozen and created a plug, or a malfunction of the thermostat, which has become “loose” after prolonged operation. Let the equipment work for 1-2 days in normal mode.
How often should you change the thermostat in the refrigerator?
The average service life of a mechanical thermostat is 10-15 years. However, with frequent voltage fluctuations or mechanical stress, it may fail earlier. If the refrigerator starts working without stopping, checking the thermostat is the first thing to do.
Does the location of the refrigerator affect its operation?
Yes, if the refrigerator is too close to the wall, radiator or in direct sunlight, the heat transfer of the condenser is disrupted. The compressor overheats and operates under increased load, which can lead to temperature failures. Maintain a gap of at least 5-10 cm from the walls.
What to do if there is ice in the freezer and heat in the refrigerator?
This is a classic sign of either a freon leak, or a clogged capillary system, or a malfunction of the thermostat. In two-chamber refrigerators with one compressor, this may also indicate problems with the cold air supply damper (if any) or that the evaporator is completely clogged with ice due to defrosting problems.