Situation, when a refrigerator, after a scheduled defrost, begins to hum continuously, ignoring the usual compressor rest cycles, it causes reasonable concern for any owner of household appliances. Constant work the motor not only increases electricity bills, but also creates the risk of complete failure of the unit due to overheating of the components. Users often panic ahead of time, forgetting about simple physical processes triggered by a long absence of cold.
Restoring the temperature in a completely defrosted chamber is stressful for the system, requiring time and resources. If you have just turned on the appliance, filled it with food and see that it has not stopped for several hours, it may be in normal mode temperature rising. However, if the unit hums for days and the cold inside never appears, or a “fur coat” forms on the walls, the problem lies deeper.
In this article we will look in detail why the refrigerator works without interruptionhow to distinguish normal operation from breakdown and which components require checking first. Understanding the principles of operation thermostat and the defrosting system will help you make the right decision: call a technician or try to fix the problem yourself.
Physiological process of temperature rise
After After complete defrosting, the interior of the chamber and the products themselves (if they have already been loaded) have an ambient temperature, often +20...+25°C. For a refrigerator, these are extremely high indicators, and its task is to lower them to specified values, for example, to +4°C in the main chamber and -18°C in the freezer. Compressor in this mode, it works at the limit of its capabilities, without going into standby mode until the target value is reached.
The duration of this process directly depends on the volume of the chambers, the number of loaded products and the temperature in the room. If you defrosted the unit in the summer in a hot kitchen, the time to reach the mode may take from 4 to 8 hours. At this time thermostat simply does not receive a signal that the temperature has reached normal, and continues to keep the compressor power circuit closed.
⚠️ Attention: If the refrigerator operates without stopping for more than 12 hours, and the temperature inside the chambers does not decrease or decreases very slowly, this indicates a malfunction. The normal “acceleration” cycle should not last for days.
It is also important to take into account the tightness of the circuit. If during defrosting you actively opened the doors or did not close them properly after loading, warm, humid air came in. Moisture Condenses on the evaporator, creating an additional heat load that is difficult for the system to cope with in standard mode.
Faults of the thermostat and sensors temperature
One of the most common reasons why the refrigerator does not turn off is the failure of thermostat (thermostat) or electronic temperature sensor. It is these elements that are responsible for controlling the climate inside the chambers and giving the command to the compressor to stop. If a mechanical thermostat is “stuck” in the “On” position or has lost calibration, it will endlessly supply current to the motor.
In models with a system No Frost and electronic control, air sensors are responsible for the temperature. Their readings may be distorted due to oxidation of contacts, moisture, or software failure of the controller. In this case, the control module “thinks” that the chamber is still hot and does not interrupt the cooling cycle.
- 🔍 Failure symptoms: the refrigerator freezes too much, turning food into ice, or, conversely, does not freeze at all, but hums constantly.
- 🔧 Diagnostics: for mechanical thermostats it is often quite accurate knock on the regulator or temporarily close the contacts to check, electronic sensors are checked with a multimeter for resistance.
- ❄️ Consequences: ignoring the problem will lead to freezing of the evaporator and eventual breakdown of the compressor due to the lack of rest cycles.
How to check a thermostat without tools?
There is a popular method for checking a mechanical thermostat. If you turn the control knob all the way to the “Off” position (or minimum cold), a working thermostat should break the circuit and click, stopping the compressor. If there is no click and the motor continues to operate even when the handle is unscrewed, the thermostat is faulty and requires replacement. However, this method does not guarantee 100% accuracy and is not suitable for all models.
Replacing the thermostat is a procedure that can be done with your own hands if you have basic skills, but requires caution when working with electrical circuits. In electronic models, replacing the sensor often requires disassembling the internal panel and resetting errors in the controller memory.
Problems with the defrost system (No Frost)
In refrigerators with the system No Frost a critical element is the defrost timer, heating element evaporator and defrost sensor. If after defrosting you turned on the unit and it started working without interruption, the system may be stuck in the cooling cycle or, conversely, cannot switch to defrost mode due to a failure.
A frequent problem is a malfunction defrost sensor or burnout of the heating element. As a result, a coat of ice builds up on the evaporator, hidden behind a plastic panel in the freezer. The fan, which should drive cold air, is blocked by ice or simply does not turn on, and temperature sensors in the chamber record heat and require the compressor to constantly work.
For diagnostics, you need to remove the back panel in the freezer and visually assess the condition evaporator. If it is completely clogged with ice and the fan is not running, then the defrost cycle is broken. This requires checking the circuit: Heating element → Defrost sensor → Timer/Control module.
☑️ Checking the No Frost system
Refrigerant leak and violation tightness
If the refrigerator is humming, trying to gain temperature, but there is no cold at all or it is very weak, there is a high probability freon leaks. Defrosting could become a catalyst if the tubes were touched during cleaning or if there was already a microcrack in the system, which appeared during the thermal expansion of metals after heating.
If there is insufficient amount of refrigerant, the compressor runs idle, trying to create a pressure that it cannot achieve. Temperature sensors see that target values have not been reached and do not issue a shutdown command. This is the most dangerous operating mode, since motor-compressor overheats, and the oil in it loses its properties.
| Symptom | Normal condition | If there is a leak frequency settings |
|---|---|---|
| Compressor operation | Cyclic (on/off) | Constant, non-stop |
| Chamber temperature | Matches settings | High, food spoils |
| Condenser temperature | Evenly warm/hot | Partly warm, partly cold |
| Sounds | Uniform humming | May be quieter than usual or with gurgling |
It is difficult to diagnose a leak on your own without special equipment (leak detector, pressure gauges). However, a visual inspection of the tubes for oily stains (freon leaves along with the oil) can give a clue. Refilling the refrigerator This is work for a professional, requiring evacuation of the system.
Wear of the compressor and start relay
Old or worn out compressor may lose its performance. The motor runs, but does not create enough pressure in the system for effective cooling. As a result, the refrigerator is forced to work continuously to compensate for the low compression efficiency.
The problem may also lie in start relay. If the relay contacts are burnt or stuck, they may not open the circuit even when the thermostat has already signaled to stop. In this case, the compressor operates until the thermal protection is activated (if it is present and in good working order) or until you unplug the cord from the socket.
⚠️ Attention: If the compressor feels excessively hot to the touch (burns your hand) and smells of burnt insulation, turn off immediately device from the network. Continuing operation may lead to a fire or motor jam.
Checking the relay is often possible at home: you need to remove it, shake it (if you hear a ringing, the core is broken inside) and inspect the contacts for carbon deposits. Replacing a relay is an inexpensive and quick procedure that often revives old refrigerators.
The influence of the external environment and proper operation
Do not discount external factors. If the refrigerator is located close to the wall, in a niche or next to the radiator/stove, it (the grill at the back) cannot effectively transfer heat. After defrosting, when the load is maximum, poor ventilation leads to the system not being able to cope with heat transfer. condenser (grille at the back) cannot release heat effectively. After defrosting, when the load is maximum, poor ventilation leads to the system being unable to cope with heat transfer.
It is also important how exactly you carried out the defrosting. Using hair dryers, hot water or sharp objects to chip ice could damage cooling circuit or the insulation. Even microscopic damage to the tube inside the wall leads to gradual leakage and the problems described above.
- 🌡️ Room temperature: If the room is hotter than +30°C, the refrigerator can work almost without interruption - this is the physical limit for many household models.
- 🚪 Closing tightness: check the rubber seals. If they do not fit tightly, the cold leaves, and warm air constantly enters.
- 🍲 Hot foods: Placing hot foods in the chamber after defrosting creates a colossal load, forcing the motor to work for hours.
Can a refrigerator break if it is not defrosted for a long time?
Yes, a long absence of defrosting (for drip systems) leads to the formation of a thick ice crust on the evaporator. Ice acts as a heat insulator, interfering with heat transfer. The compressor begins to work longer to break through the ice, which leads to its overload. In No Frost systems, disruption of defrosting due to ice also leads to failure of the fan or heating element.
How long does it take the refrigerator to gain temperature after complete defrosting?
Usually the process takes from 2 to 6 hours to reach operating temperatures in an empty chamber. If the chamber is loaded with products, the time can increase to 8-10 hours. If after 12 hours the temperature does not stabilize, you should look for a malfunction.
Why does the refrigerator hum loudly after defrosting?
Increased noise may be due to vibration of the tubes, which may have moved during cleaning, or to the operation of the compressor under maximum load. A fan in the No Frost system can also make noise if there is ice left on its blades or it touches the wiring.
What to do if a burning smell appears after defrosting?
The burning smell may indicate overheating of the wiring, start relay or the compressor itself. It is necessary to immediately unplug the device, allow it to cool and conduct a visual inspection of the rear part and internal components. Operating such a device is dangerous.