The situation when the refrigerator continues to hum, the light is on, but there is room temperature inside always takes you by surprise. This is a classic scenario that can lead to the spoilage of a large stock of food if not reacted in time. Many users mistakenly believe that since the motor runs and makes sounds, it means the system is working, but in reality this often indicates a hidden defect in the cooling circuit.
The first thing that needs to be done is to carry out initial visual and other (auditory) diagnostics, without immediately resorting to complex tools. Temperature violation can be caused by either a simple overload of the chamber or a serious leak refrigerant. It is important to understand the difference between normal operation of the unit and emergency mode, so as not to aggravate the situation.
In most cases, the problem lies in one of three main systems: a sealed circuit, a defrost system or electronic control. Two-compressor models may behave differently than single-compressor systems, so there is no universal solution does not exist for all brands. Below we will analyze each aspect in detail so that you can accurately determine the source of the malfunction.
Checking the tightness and integrity of the circuit
The most common and unpleasant reason for the lack of cold when the compressor is running is freon leak. The refrigerant circulates through a closed system of tubes, and if a microcrack or fistula forms in the metal, the gas gradually evaporates into the atmosphere. It is impossible to notice this visually, since freon is colorless and odorless, but the effect of its absence will be obvious: the compressor hums continuously, trying to gain temperature, but heat exchange does not occur.
Often a leak occurs in places where tubes are soldered or in the evaporator, which could be damaged during careless defrosting. If you previously picked out the ice with a knife and accidentally pierced the wall, then the seal was broken at that very momenteven if the refrigerator continued to work for several more days. Over time, the pressure drops so much that the compressor can no longer cope with the load, although electrically it is fully operational.
⚠️ Attention: Self-filling the refrigerator with freon without finding and eliminating the leak is a waste of money. Gas will escape again through the same crack within a few days or even hours.
A leak can be diagnosed by indirect signs: a hot condenser (grid at the back) only at the beginning of the cycle or when it cools completely, as well as by the absence of a characteristic gurgling sound in the tubes when the engine stops. In modern models with No Frost leakage can be manifested by swelling of the back wall in the freezer due to moisture getting there and its subsequent freezing in places of depressurization.
Faults in the compressor and start relay
The compressor is the “heart” of the refrigeration unit, creating the necessary pressure for refrigerant circulation. It happens that the engine hums, but does not start, or starts for a few seconds and immediately stalls with a characteristic click. This is a sure sign that starting relay has failed or the compressor itself has a mechanical or electrical defect. The relay is responsible for providing an impulse to start the motor windings, and its breakdown is one of the most common causes of equipment failure.
If the compressor runs continuously without turning off for hours, but there is no cold, this may indicate a loss of its performance. The piston group could have worn out, the valves could have stuck or burned out, which is why the compressor does not create the required pressure in the system. In this case, it simply circulates the gas in a circle without a compression effect, consuming electricity but not producing cold.
To check the relay, it is often enough to remove it and shake it: if a ringing is heard inside, it means the mechanical part is destroyed. However, in models with inverter compressor the situation is more complicated: there is no classic starting relay, and the start is controlled by an electronic module. Diagnostics of such systems requires special tools and knowledge of electronics.
- 🔊 A loud metallic knock or clanging sound during startup indicates destruction of the compressor suspension or internal mechanisms.
- 🔥 Strong heating of the motor housing (to the point where when you cannot touch it with your hand) may indicate an interturn short circuit of the windings.
- ⚡ Frequent clicks and attempts to start indicate that the thermal protection relay is trying to save the motor from overload.
Problems with the defrost system (No Frost)
In refrigerators with a system No Frost or Full No Frost the lack of cold is often associated with ice freezing on the evaporator, which is hidden behind a plastic panel. If the automatic defrosting system fails, the ice coat grows and blocks the channels through which cold air should enter the chamber. The fan is humming, the compressor is running, but the air flow is blocked by an ice plug.
Three main elements are responsible for the defrosting process: a heating element (heater), a defrost sensor (thermostat) and a timer (or electronic control module). If any of these components fail, the ice will not melt. For example, if it burns out Defrost heating elementit does not heat the evaporator and the ice remains in place. If the sensor is faulty, it does not give a command to turn on the heating or, conversely, does not turn it off in time.
You can diagnose this problem by paying attention to the back wall in the freezer. If it swells or flexes like soft plastic when pressed, ice has probably accumulated underneath it. Another sign may be that after the refrigerator has completely defrosted for 24 hours (with the doors open), it begins to freeze normally, but after a week the problem returns.
How to check the defrosting heating element?
To check the heating element, you need a multimeter in resistance measurement mode. You need to get to the evaporator (by removing the back panel in the freezer), disconnect the contacts of the heating element and ring it. If the device shows a break (one or infinity), the heating element has burned out and requires replacement. The normal resistance of a working heating element is usually from 200 to 400 Ohms.
Failures in the operation of the thermostat and electronics
The thermostat (thermostat) is a device that “tells” the compressor when to turn on and when to turn off. If it is faulty, the refrigerator may simply “not know” that the temperature inside has increased. In this case, the compressor will stand idle, even if it is already warm inside, or, conversely, work without stopping if the contacts are stuck in the “on” position, but there will be no cold due to other accompanying factors.
Modern models use air temperature sensors instead of a mechanical thermostat. If the sensor is lying or the module does not supply voltage to the compressor, the refrigerator will not work. Often, in this case, an error lights up on the display or the temperature indication blinks, which greatly simplifies diagnostics compared to mechanical models. electronic control module and air temperature sensors. If the sensor is lying or the module does not supply voltage to the compressor, the refrigerator will not work. Often, in this case, an error lights up on the display or the temperature indication blinks, which greatly simplifies diagnostics compared to mechanical models.
Checking the thermostat in mechanical refrigerators is simple: you need to short-circuit the two wires coming from it, bypassing the device itself. If after this procedure the compressor starts, it means the thermostat is faulty and requires replacement. However, it is worth remembering that in some models the thermostat has a third wire to turn on a fan or light bulb, and the circuit may differ.
| Symptom | Probable cause | Characteristic symptom |
|---|---|---|
| The compressor is silent, there is no light | No power, plug/socket burned out | The light inside does not light |
| The compressor hums, but does not start | The starting relay is faulty | Clicks at regular intervals time |
| Works continuously, no cold | Freon leakage or compressor wear | Condenser is only partially warm |
| The freezer is freezing, the refrigerator is warm | Faulty No Frost system or damper | Ice on the back wall of the freezer |
Clogged capillary tube
A capillary tube is a thin copper channel in which a sharp drop in refrigerant pressure occurs, necessary for it to evaporate and absorb heat. If oil oxidation products, moisture or technical debris appear in the circulation system, oil-technological blockagemay form. In this case, there is freon, the compressor is working, but gas circulation is impossible.
A sign of a blockage is often the unusual behavior of the condenser: it can be hot only at the very beginning (near the compressor) and cold further, or vice versa, the entire circuit remains cold, and the compressor overheats greatly due to work being “at a dead end”. The pressure at the outlet of the compressor increases, and at the inlet to the evaporator drops to a vacuum.
Removing the blockage is a complex procedure that requires flushing the system with nitrogen under high pressure, replacing the filter-drier and evacuation. At home, it is almost impossible to do this efficiently, since special equipment is required to work with the refrigeration circuit.
☑️ Primary diagnostics of the refrigerator
Mechanical damage and seals
Sometimes the reason for the lack of cold is trivial and lies in the violation of the tightness of the chamber itself, and not the refrigeration circuit. If sealing rubber the door is worn out, dirty or deformed, warm air constantly flows inside. The compressor works hard, trying to compensate for the heat influx, but cannot cope with the volume of the task.
You can check the tightness of the door in a simple way: hold a sheet of paper between the door and the body and try to pull it out. If the paper pulls out without resistance in several places, the seal is broken. It is also worth checking the door hinges: if they are loose, the door warps and does not fit tightly, even if the elastic is intact.
⚠️ Attention: Frequently opening the door or leaving it ajar for a long time also leads to overload of the compressor. Make sure that the refrigerator is not close to the wall and that nothing prevents the door from closing completely.
In addition, mechanical damage may be internal. For example, if the refrigerator was tilted or shaken strongly during transportation, the internal tubes could become dislodged or the compressor suspension parts could become torn off. In such cases, repairs require disassembling the unit and restoring the geometry of the pipelines.
Is it possible to repair a refrigerator with a freon leak on your own?
Theoretically, you can find the location of the leak (by immersion in water or a soap solution) and solder it if you have a torch and solder. However, to charge the system with freon, a vacuum pump, a pressure gauge station and scales for gas dosing are required. Without these tools, it will not be possible to properly refill the refrigerator, so calling a technician in case of a leak is the only reasonable solution.
How long does the refrigerator remain cold after being turned off?
The time it remains cold depends on the model, load and ambient temperature. Typically, a fully loaded freezer will keep its temperature for up to 24 hours, and a refrigerator will hold its temperature for up to 6-8 hours if the door is not opened. An empty refrigerator cools down much faster.
Why did the refrigerator begin to work worse after defrosting?
If after defrosting the cold became less, you may have damaged the evaporator tubes with a sharp object, breaking the seal. The defrost system could also fail (the heating element or sensor burned out), which worked by inertia, and after the defrost cycle stopped functioning. The third option is that you simply loaded the warm refrigerator too much with food, and it did not have time to go into operation.
What to do if the refrigerator hums, but does not turn on?
If you hear a hum, but the compressor does not start (or immediately clicks and stalls), most likely the problem is in the start relay or the compressor is jammed. Try turning off the device from the network for 15-20 minutes, then turning it on again. If the situation repeats, it is necessary to replace the relay or have the compressor diagnosed by a technician.