The situation when the refrigerator compressor runs continuously, hums, but the inside of the chamber does not get colder, is critical for the safety of food. This condition indicates that refrigerant is not performing its function, or the temperature control system has failed. Unlike normal operation, where the motor turns on and off according to a timer or sensor indicators, here we observe either a loss of cooling capacity or an incorrect command to stop.
There can be several reasons for this behavior of the equipment: from the banal door not tightly closed to the serious freon leaks. It is important to understand that prolonged operation of the compressor without stopping in the absence of cold leads to overheating of the motor windings. Ultimately, this can cause insulation melting and complete failure of the unit, which will require expensive replacement.
In this article we will analyze in detail the mechanical, electrical and physical causes of the malfunction. You will learn how to carry out initial diagnostics yourself, what sounds you should pay attention to and in what cases call a specialist is the only correct solution to restore the functionality of your refrigerator.
Problems with tightness and refrigerant leakage
The most common reason why a refrigerator runs continuously but does not cool is a leak in the circuit. If freon (the refrigerant) evaporates through microcracks in the evaporator or condenser tubes, its volume becomes insufficient for effective heat exchange. The compressor tries to compensate for the lack of pressure, working for wear, but the temperature in the chambers remains at room temperature.
Often, leakage occurs in places where tubes are soldered or in areas subject to vibration. It is difficult to determine this visually, since the gas is colorless and odorless. However, an indirect sign may be the absence of characteristic gurgling or hissing, which is usually heard when a working unit is operating. Also, traces of oil may appear on the rear wall of the radiator where the gas exits.
⚠️ Attention: If you find oil stains on the floor under the refrigerator or on the rear grille, the probability of a freon leak is almost 100%. You cannot seal the system yourself without a vacuum pump and a filling scale - this will lead to breakdown of the compressor.
To diagnose leaks, technicians use leak detector or a soap solution, applying it to suspicious areas of the pipeline. The appearance of bubbles will indicate the location of depressurization. After eliminating the defect, the system must be evacuated to remove moisture and air, after which it is charged with a strictly defined amount of refrigerant.
How long does freon last in a refrigerator?
Freon is an inert gas that is not consumed during operation, like gasoline in a car. If the system is sealed, it circulates in it for decades. The need for refueling always indicates the presence of a crack or fistula in the circuit.
Malfunctions of the thermostat and temperature sensors
The thermostat (thermostat) is the “brain” that commands the compressor to turn on or stop. If this element fails and its contacts are “stuck” in the “on” position, the motor will run endlessly, ignoring the real temperature inside the chambers. In modern models with electronic control, the temperature sensor or air damper is responsible for this.
You can check a mechanical thermostat by temporarily closing its contacts or, conversely, turning them off. If the compressor stops when the regulator is turned off, then that is where the problem lies. In electronic models, diagnostics are more complicated and require checking the resistance of the sensor with a multimeter at different temperatures.
A frequent problem is not the breakdown of the sensor itself, but its displacement. If capillary tube the thermostat has moved away from the evaporator or the sensor has flown out of its seat, it reads the air temperature in the chamber, and not the temperature of the cooling element. Since the air cools more slowly, the command to turn off the motor comes too late or does not arrive at all.
Replacing the thermostat is a procedure that you can do yourself if you have electrical skills. However, in models with a system No Frost access to the sensor is often hidden behind plastic panels and the evaporator, which requires partial disassembly of the inside of the refrigerator.
Clogging of the capillary tube (System)
The capillary tube is a thin copper pipeline in which throttling occurs (a sharp decrease in pressure) refrigerant before it enters the evaporator. If low-quality freon circulates in the circulation system or moisture gets into the circuit, an ice plug or a blockage from oil oxidation products may form inside the tube.
If blocked, the refrigerant cannot circulate freely throughout the circuit. The compressor tries to push the gas, creating excess pressure at the discharge and vacuum at the suction, but the cooling capacity drops to zero. A characteristic sign of such a malfunction is that the condenser (grid at the back) can be hot only at the beginning, and the evaporator inside the chamber can only be cold at the entrance.
To eliminate this problem you need:
- 💨 Blowing the circuit with nitrogen at high pressure to remove debris.
- 🔥 Replacement capillary tube with a new one, since it is often impossible to clean the old one.
- 💧 Replacing the filter-drier, which must be installed in front of the capillary.
The procedure for removing blockages is technically complex and requires specialized equipment. At home, trying to clean the tube with a wire or a pump without evacuating the system will only lead to moisture and air getting inside, which will finally “kill” the compressor.
Wear of the compressor and loss of performance
The compressor is the heart of the refrigerator. Over time, the mechanical parts inside it (pistons, valves, connecting rods) wear out. If the compressor is "tired", it may continue to hum and consume electricity, but not create the necessary pressure to circulate freon. This condition is called loss of compression.
>Wear can be determined by the nature of the sound and the temperature of the case. An older motor often runs louder, with a metallic clanging or humming sound. In this case, the compressor housing may be barely warm, although it should feel hot (about 70-90°C) in the area of the discharge discharge tube.
Another reason for low efficiency is air leakage through leaks in the suction pipe or malfunction of the valves inside the cylinder head. In this case, the engine runs idle. Compressor diagnostics include measuring the winding current and output pressure using a pressure gauge station.
Violation of the chamber tightness and system operation No Frost
Sometimes the problem lies not in the hardware, but in the operating conditions. If the rubber seal on the refrigerator door is worn out, torn or simply dirty, warm air from the room constantly enters the chamber. Sensors detect an increase in temperature and command the compressor to work continuously to compensate for the heat influx.
In refrigerators with a system No Frost the situation can be aggravated by a malfunction of the defrost system. If the evaporator heating element, timer or defrost sensor fails, the evaporator becomes covered with a “coat” of ice. Air stops circulating through the radiator clogged with ice, and the cold does not enter the chamber, although the engine hums without interruption.
To check the seal, use a simple test with a sheet of paper:
- 📄 Press the sheet of paper with the refrigerator door around the perimeter.
- 🚪 Try to pull the sheet out: it should come out with noticeable effort.
- 🔥 If the sheet falls out freely or is removed without resistance, the seal does not hold the cold.
Regular defrosting (for drip systems) and cleaning the drainage hole helps prevent many problems. If you notice that water is accumulating under the refrigerator or inside on the floor, this may be a sign that the system is not coping with the removal of condensate, which also affects the operating efficiency.
☑️ Primary diagnostics of the refrigerator
Diagnostics and table of symptoms
To accurately determine the cause of the malfunction, it is important to compare several symptoms. Below is a table that will help you navigate the nature of the breakdown before the technician arrives.
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| The compressor is hot, but does not freeze | Freon leak or system blockage | High (tool needed) |
| The motor is humming, but the body is cold | Loss of compression (motor wear) | High (replacement unit) |
| The refrigerator freezes, but does not turn off | The thermostat or sensor is faulty | Medium (sensor replacement) |
| A bubbling noise is heard, there is no cold | Air has entered the system or there is not enough freon | Medium (vacuuming and refilling) |
| There is a coat of ice in the chamber, there is no cold | Malfunction of the defrost system (No Frost) | Medium (replacing heating element/timer) |
When carrying out diagnostics, always disconnect the device from the power supply before removing panels and casings. Working with live electrical components is prohibited.
⚠️ Attention: Refrigerant specifications and oil types vary depending on the model and year of manufacture. Using the wrong freon (for example, R134a instead of R600a) may result in an explosion or fire. Always check the data on the compressor nameplate.
When you need to call a specialist
Despite the desire to save money, there are situations when do-it-yourself repair is impossible or dangerous. If the problem is related to a violation of the tightness of the circuit (leakage, blockage), professional equipment is required: a vacuum pump, a pressure gauge station, scales for weighing freon and a torch for soldering.
Also, you should not change the compressor yourself. This process includes not only mechanical installation, but also proper soldering of the tubes in a nitrogen protective environment (so that scale does not form inside), prolonged vacuuming of the system to remove moisture, and precise charging. An error at any stage will lead to a second breakdown in a short time.
If your refrigerator is under warranty, any independent intervention, removing seals or violating the integrity of factory stickers will lead to loss of warranty obligations. In this case, the only correct solution would be to contact an authorized service center.
Frequently asked questions (FAQ)
How long can the refrigerator operate without turning off normally?
In normal operation, the refrigerator turns on and off cyclically. The operating time depends on the load, room temperature and model, but usually the cycle is from 15 to 40 minutes of work and about the same amount of rest. Continuous operation for more than 24 hours without a break (provided that the door did not open constantly) is considered a malfunction.
Is it possible to operate the refrigerator if it does not turn off, but the food does not spoil yet?
You can operate the equipment in this mode only for a short time (several hours) while you wait for the technician or carry out diagnostics. Prolonged operation at the limit will lead to overheating of the motor windings, oil degradation and (eventually) seizure of the compressor. Repairs in this case will cost much more.
Why does the refrigerator not turn off for a long time after defrosting?
Immediately after defrosting and loading warm food, the compressor may work longer than usual to reach the set temperature. This is fine. However, if it does not turn off for more than a day, you may have damaged the system during defrosting (for example, pierced the evaporator with a knife) or moisture got into the system.
Does the temperature in the room affect the operating time of the refrigerator?
Yes, it does. If the refrigerator is located next to a radiator, stove or in direct sunlight, and also if the room is hot (+30°C and above), the compressor will work almost without interruption, trying to compensate for the heat gain. Under such conditions, efficiency decreases and wear increases.