In modern refrigerators with system No Frost the ice removal process occurs automatically, without user intervention. The key element of this system is the heating element, or Heating element, which is activated according to a special algorithm. Understanding exactly when it turns on helps diagnose malfunctions and properly care for the equipment.
Unlike old models with a “crying” wall, here the evaporator is hidden behind a plastic panel. The ice that forms on it during the operation of the compressor periodically melts under the influence of heat. The defrosting heating element is turned on only when the timer records the accumulation of a certain number of compressor operating cycles or reaches a specified time interval.
The frequency of heater starts directly affects the energy consumption and service life of the unit components. If the heating element heats up too often, this will lead to unnecessary electricity consumption, and if rarely, the evaporator will become overgrown with a “fur coat” and will stop cooling the chamber. Let's look at the details of this process.
The operating principle of the automatic defrosting system
The basis for controlling defrosting cycles is timer or an electronic control module. Classic schemes use a mechanical timer that counts the operating time of the compressor. Typically, the ratio is as follows: for every 16 hours of operation of the refrigerator, there are 15–20 minutes of defrosting. In more modern models Indesit or Beko this function is taken over by smart electronics that analyze the real situation.
The startup process is as follows: the compressor turns off, the fan stops (if this model has one), and voltage is applied to the heater. It is important to understand that at this moment the refrigerator does not cool the food, but spends energy melting the ice. The temperature in the chamber may increase slightly, but this is a normal situation.
There are two main types of control:
- 🕒 Temporary: launch strictly according to schedule, regardless of the amount of ice.
- 🌡️ Adaptive: launch occurs only when necessary, which saves resources.
- ⏱ Combined: the timer gives the command to start, but sensors control the process.
You should not try to interfere with the operation of electronics unless necessary. If the system defrosts does not work correctly, it is better to call a technician to diagnose the sensors rather than experiment with the settings.
The role of temperature sensors and thermostats
Simply turning on the heater is not enough - its operation must be strictly controlled. For this purpose, defrosters are installed in the system. Their task is to break the power supply circuit of the heating element when the evaporator temperature reaches a certain value (usually +10...+15°C). This prevents overheating of plastic parts and air ducts. defrost thermostats (defrosters). Their task is to break the power supply circuit of the heating element when the evaporator temperature reaches a certain value (usually +10...+15°C). This prevents plastic parts and air ducts from overheating.
The second important element is evaporator temperature sensor. In electronic models, it transmits data to the control board. If the sensor “sees” that the ice has not yet completely melted, it can extend the operating time of the heating element. If the sensor is faulty and shows a low temperature, the heater may work for too long or not turn on at all.
⚠️ Attention: The defrost thermostat should be replaced only after the refrigerator has completely defrosted. Installing a new sensor on a hot or wet evaporator will lead to its immediate failure or incorrect readings.
Typical sequence of protection operation:
- ❄️ The evaporator temperature drops below -5°C - heating element turned off.
- 🔥 The defrost cycle begins, the temperature rises.
- ✅ When +10°C is reached, the thermostat opens the contacts.
Sometimes users are faced with a situation where the heating element “sticks” when turned on. This is a rare but dangerous malfunction that can cause the plastic to melt. In such cases, the electronics of modern brands, such as LG or Samsung, often block further operation of the compressor until the error is eliminated.
Time intervals: how often defrosting occurs
The question “how often does the heating element turn on” does not have a single answer for all models, since algorithms are different. On average, a full defrost cycle in household refrigerators occurs every 8-12 hours operation of the compressor. However, this time may vary depending on the load of the chambers and the frequency of opening the doors.
If you often open the refrigerator, warm, moist air gets inside. Moisture settles on the evaporator and quickly turns into ice. In this case, the intelligent system can reduce the interval between turning on the heating element to prevent the formation of an ice block. Conversely, with rare use, the intervals may increase.
The duration of the heating process itself is also regulated. Typically the heating element operates from 15 to 45 minutes. This time is enough to melt even a significant layer of frost. After heating is completed, the system waits until the water drains into the drain pan, and only then starts the compressor again.
The table below shows approximate dependences of the operating time of the heating element on operating conditions:
| Operating condition | Turning frequency of the heating element | Duration cycle |
|---|---|---|
| Standard loading | Every 12 hours | 20 minutes |
| Frequent door opening | Every 6-8 hours | 30-40 minutes |
| High humidity in the room | Every 8 hours | 25-30 minutes |
| Empty refrigerator | Every 16-20 hours | 15 minutes |
Diagnostics of defrost heating element faults
If the heating element stops turning on, the evaporator becomes overgrown with ice, which blocks the air circulation channels. As a result, the refrigerator compartment becomes warm, and snowdrifts may appear in the freezer. The first sign of a malfunction is often fan humwhich begins to touch ice chips, or the complete absence of fan operation noise.
Checking the integrity of the heater is performed using a multimeter in resistance measurement mode. The normal resistance of the heating element is usually in the range from 200 to 400 Ohms. If the device shows an open circuit (infinity) or a short circuit (zero), the element must be replaced. It is also worth checking the integrity of the wires going to the heating element, as they often burn out or are interrupted by ice.
☑️ Symptoms of a malfunction of the heating element
A frequent problem is not the breakdown of the heating element itself, but the failure safety thermostat. It may “break” and simply not supply voltage to the heater, even if the heating element itself is working. Therefore, diagnostics always begin with checking the entire circuit.
⚠️ Attention: Before taking any measurements with a multimeter, be sure to disconnect the refrigerator from the power supply. An attempt to measure resistance under voltage will result in the device burning out and possible electric shock.
The influence of operating mode on energy consumption
Many users are worried that frequent operation of the heating element significantly increases electricity bills. Indeed, the heater consumes energy, but its contribution to the overall balance is not as great as the work of the compressor. The heating element turns on rarely and for a short time, so its share in consumption is about 10-15% of the total energy consumption of the refrigerator.
However, if the defrosting system does not work efficiently (for example, the heating element turns on too often or does not turn off on time), energy consumption may increase. Modern inverter compressors paired with a smart defrost system can minimize these losses. Models with energy efficiency class A++ and higher have optimized algorithms that eliminate unnecessary heating cycles.
How much energy does a heating element consume?
The power of a heating element in a household refrigerator usually ranges from 150 to 400 Watts. When running for 20 minutes (1/3 hour) it will consume approximately 0.05 - 0.13 kWh. During the day this will amount to no more than 0.5 kWh, which at a tariff of 5 rubles per kWh will cost 2.5 rubles.
To reduce the load on the defrosting system and save energy:
- 🚪 Do not keep the doors open longer than necessary.
- 🍲 Cool hot food before placing it in the chamber.
- 🧊 Check the tightness of the door seals.
Frequently asked questions about defrost cycles
Refrigerator owners often ask questions related to the sounds and behavior of equipment during defrosting. Below are the answers to the most popular of them.
Why does the refrigerator gurgle and click when the compressor is not working?
This is a normal process. During defrost, the ice turns into water, which drips into the drainage system, creating gurgling sounds. The thermostat or relay that switches operating modes makes clicking noises. Plastic may also crack due to temperature changes.
Is it possible to speed up defrosting if the heating element is broken?
Artificially speeding up the process (for example, by blowing a hair dryer inside the air ducts) is dangerous. You may damage the plastic or sensors. If the heating element is faulty, it is better to defrost the refrigerator completely (for 24 hours with the doors open) and call a technician to replace the part.
Does the room temperature affect the frequency at which the heating element turns on?
Yes, indirectly. In a hot room, the compressor runs more often to maintain the cold. Since defrost cycles are often tied to the operating time of the compressor, the heating element will also turn on more often. In addition, in hot weather, more moisture enters the chamber when the doors are opened.
What happens if the water from defrosting does not have time to evaporate?
The water flows into a special tray above the compressor, where it evaporates naturally. If there is too much water (for example, you loaded a lot of warm food), it may overfill the tray and leak onto the floor. In this case, you need to check the drainage hole for blockages.
Is it necessary to defrost the No Frost refrigerator manually?
Manufacturers recommend carrying out a complete preventative defrosting at least once a year, even if the system is working properly. This allows you to clean hard-to-reach places from bacteria and check the condition of the drainage system, which the automation cannot “clean.”