The situation when the compressor of the refrigeration unit hums continuously, trying to reach the set temperature, but inside the chamber still warm, is one of the most critical for the safety of products. Continuous operation of the engine without achieving the target indicators indicates that the cooling system has ceased to perform its function, although the electrical circuit is closed and the motor is receiving power. This may indicate either a simple refrigerant leak or more complex mechanical failures in the compressor components or the heat removal system.
Owners often notice the problem too late, when the products have already begun to deteriorate, and the back wall of the chamber, which normally should be cold or covered with frost (depending on the type defrosting), remains warm. Freon circulation is broken, and the refrigerant has either evaporated through microcracks or is stuck in one of the sections of the circuit due to a blockage. Understanding the physics of the process will help you quickly determine the troubleshooting vector without immediately resorting to an expensive call to a technician.
If you hear a characteristic gurgling or hissing, but cold does not appear, this is a sure sign that there is a working substance in the system there is no necessary pressure . In some cases, the unit can work for days, consuming a huge amount of electricity, but without creating cold, which ultimately leads to overheating of the motor windings and its complete failure. It is important to respond quickly to the first symptoms so that repairs are cheaper than replacing the entire compressor.
Refrigerant leakage as the main reason for the lack of cold
The most common reason why a refrigerator stops freezing when the compressor is running is a banal freon leak. The refrigerant circulates through a closed circuit consisting of thin evaporator and condenser tubes. Over time, the metal undergoes corrosion, especially in solder areas or in hidden foamed areas where moisture causes oxidation. Microscopic cracks allow the gas to slowly evaporate into the atmosphere, reducing the efficiency of heat transfer to zero.
Visually detecting a freon leak is almost impossible, since it colorless and odorless gas. However, indirect signs are swelling on the inner or outer wall of the housing, as well as oily stains in the compressor area or on the floor under the unit. The oil comes out along with the gas, leaving marks where the fistula formed. If pressure in the system falls, the compressor tries to compensate for this by continuous operation, but there is nothing left for it to pump.
⚠️ Attention: Do not try to find the leak yourself using a soap solution if you do not have access to the rear panel and the condenser. In modern models with a foamed evaporator, this is useless and can lead to damage to the insulation.
The process of restoring the system after a leak requires professional intervention. The technician must not only refill the gas, but also find the location of the damage, eliminate it and replace the filter-drier. Filter drier necessary to remove moisture that inevitably enters the circuit during depressurization. If you simply add freon without evacuation and replacing the filter, the remaining moisture will freeze in the capillary tube, creating an ice plug, and the refrigerator will stop cooling again after a short time.
How long does freon last in a refrigerator?
Freon is not consumable material in the classical sense. In a serviceable, sealed circuit, it circulates for decades without replacement. If “refilling” is required, this always means there is a malfunction (leak) that needs to be repaired.
Clogged capillary tube and ice plug
The second most common reason for continuous operation without cooling is a clogged capillary tube. This assembly is a very thin copper channel connecting the high and low pressure areas. Through it, liquid freon is injected into the evaporator. If compressor wear products, oxides or dirt circulate in the system, they can clog this narrow passage. The formation of ice plug from frozen moisture that has entered the circuit is also common.
Symptoms of a blockage are similar to a leak: the compressor is humming, the condenser (grid at the back) may be hot at the beginning and cold at the end, and there is no cold in the freezer. If you try to defrost the unit during the day, the problem may temporarily disappear (if the plug is icy), but then return again. Mechanical blockage requires purging the system with nitrogen under high pressure or replacing a section of the tube.
Diagnostics of blockage is often carried out by the temperature of the filter drier. If, after switching on, it remains cold or is covered with frost, and the condenser is only half hot, it means that the circulation of freon is disrupted in this particular place. Capillary tube does not allow refrigerant to pass through, and the pressure at the inlet of the compressor drops, although the motor itself is working for wear.
To eliminate this malfunction you need:
- 🛠️ Vacuuming systems for removing air and moisture.
- 🔥 Blowing the circuit with dry nitrogen to eliminate mechanical impurities.
- ❄️ Replacement filter-drier with a new one (reusing the old one is unacceptable).
- 💉 Accurate refrigerant charging by weight according to the model data sheet.
Malfunctions of the thermostat and temperature sensors
If the refrigerator does not turn off, but it may even be too cold inside the chamber (or vice versa, warm if the sensor is lying in the other direction), the problem may lie in the control electronics or mechanical thermostat. Thermoregulator is a device that closes and opens the electrical circuit of the compressor depending on the temperature in the chamber. If its contacts are “stuck” in the “on” position, the motor will operate continuously.
In models with electronic control (No Frost), the temperature is monitored thermal sensors (thermistors). They are resistors that change resistance when heated or cooled. If the sensor fails and shows the control module that the chamber is +20°C, although in reality it is +5°C, the “brain” of the refrigerator will command the compressor to work without stopping. You can check the health of the sensor with a multimeter by measuring its resistance at different temperatures.
Often users confuse sensor failure with incorrect settings. Make sure that the Super Freeze (Super Freeze) mode is not activated, which forcibly keeps the compressor on for a long time. It is also worth checking the tightness of the door: if the seal is worn out, warm air constantly gets inside, and even a working sensor will require constant operation of the unit.
| Symptom | Possible cause | Nature of compressor operation |
|---|---|---|
| The refrigerator does not freezing, warm inside | Freon leak/clogging | Works continuously, hot |
| In the "glacier" chamber, food freezes | Thermostat/sensor is faulty | Does not turn off completely |
| Clicks are heard, the cold disappears | Starting relay or motor | It turns on and turns off immediately |
| It makes noise, but there is no cold | Loss of performance compressor | Works quietly or loudly, without pauses |
Problems with the compressor: loss of performance
The most unpleasant and expensive option is failure of the very heart of the refrigerator, the compressor. Over time, the valves inside the motor wear out, the piston group loses its tightness, and the unit ceases to create the necessary pressure difference. It hums, vibrates, but pumps freon extremely weakly or does not pump at all. In this case, the refrigerator can work for days, consuming electricity, but not creating cold.
It is difficult to diagnose a loss of performance “by ear,” but an experienced technician will determine this by the temperature of the suction and discharge tubes. If the tube at the outlet of the compressor (discharge) is barely warm, and at the inlet (suction) it is at room temperature, then the compressor is not creating pressure. Also a sign may be overheating of the motor housing above normal (more than 90°C).
⚠️ Attention: An attempt to replace the compressor yourself without professional equipment (burner, vacuum pump, pressure gauge station) is doomed to failure. Incorrect soldering or refueling will lead to rapid breakdown of the new expensive unit.
In some cases, the cause of the "imaginary" breakdown of the compressor is starting relay. This is a small part that supplies a starting impulse to the motor winding. If the relay is faulty, the compressor may hum, jerk but not start, or start and immediately stall. Replacing a relay is a simple and cheap procedure that you can do yourself by selecting an analogue according to the marking.
The influence of the No Frost mode and the defrost system
In the refrigerators of the system No Frost (without frost), the reason for the lack of cold when the engine is running may lie a malfunction of the evaporator defrost system. If the defrost heating element, timer or defrost sensor fails, the evaporator (located behind the rear wall) becomes coated with ice. The fan, which is supposed to drive cold air into the chamber, is either stopped by ice, or drives air through an ice monolith that does not allow cold to pass through.
As a result, the compressor works non-stop, trying to cool the chamber, but the cold simply does not reach the food. Outwardly, this may manifest itself in the fact that it is still cold in the freezer, but warm in the refrigerator compartment. Or the cold appears only after the refrigerator has completely defrosted for 24 hours, and then disappears again after a couple of days.
You can check this hypothesis by carefully disassembling the back panel in the freezer (after disconnecting the unit from the mains). If you see a block of ice there hiding the radiator fins, the defrost cycle is broken. It is necessary to check the circuit: Timer → Heating element → Defrost sensor. Often the heating element itself burns out or the sensor “sticks” without giving a command to turn on the heating.
☑️ Diagnostics of the No Frost system
External factors and errors operation
Before you panic and call a technician, you should exclude external factors that simulate a breakdown. Often the refrigerator does not cool because the rules for its operation have been violated. For example, if the unit is located close to a wall or in a niche without gaps for ventilation, the condenser does not have time to cool down. Heat transfer is broken, efficiency drops, and the motor operates at its limit.
It is also important to consider the volume of loaded products. If you put a lot of indoor food in a warm refrigerator at once, it will last a long time. But if it can’t cope even with an empty chamber, it’s a breakdown. Check the tightness of the door: a stuck bag or skewed hinges allow warm air to penetrate inside, causing the equipment to run idle.
The temperature in the room also plays a role. If the refrigerator is placed on an unheated loggia or next to a radiator, where the temperature is below +10°C or above +30°C, it may not work correctly. At low temperatures, the oil in the compressor thickens, and at high temperatures, the condensation pressure increases, which leads to emergency operating conditions.
Why does the refrigerator hum, but does not freeze after defrosting?
If after complete defrosting (24 hours) the refrigerator turned on, worked for a couple of hours and stopped freezing again, continuing to hum, this is almost guaranteed to indicate a freon leak or blockage. Defrosting temporarily removes the ice plug in the capillary (if there was one), but the main reason (leaks or dirt in the system) does not go away.
Is it possible to operate the refrigerator if it does not turn off?
For a short time - yes, if you are waiting for a technician. However, prolonged operation in this mode (a day or more) leads to overheating of the compressor windings and its combustion. If you notice that the unit does not turn off for more than 6-8 hours and does not cool, it is better to disconnect it from the network to avoid a fire or an expensive motor replacement.
How can you tell that the compressor has burned out?
Signs of a burnt-out compressor: the unit does not turn on at all, you hear a click and silence, or the machine in the control panel knocks out. If it hums but does not cool, it is most likely alive, but has lost performance or there is no freon in the system. You can check the breakage of the windings with a multimeter by ringing the contacts of the starting relay.
What to do if the gas has left, and the repairman will arrive in 3 days?
It is better to transfer the products to another cold place or use dry ice. Leaving a refrigerator running empty for several days is dangerous: the compressor can burn out from overheating, and repairs will become much more expensive. It is better to keep it turned off with the doors open.