Modern refrigeration systems units, whether models Indesit, LG or Beko, are equipped with automatic defrosting systems. Owners often wonder how to turn off the defrost on the refrigerator when they notice an error indicator or hear strange sounds. Usually this means forcibly turning on the defrosting mode to check the functionality of the heating element or, conversely, turning off the system to take measurements with a multimeter.
It is important to immediately understand: it is impossible to turn off the evaporation of ice in the mode using standard buttons on the control panel. No Frost is impossible. This is an emergency or service function. If a “fur coat” has formed in the chamber, and the compressor hums without interruption, it means that the defrost cycle is broken. You will need access to the electronic board or mechanical timers hidden inside the case.
Next we will look at the technical nuances of the operation of Evaporator heating element sensors, as well as ways to force them to be activated for testing. This knowledge is critically important for a technician who wants to accurately determine the malfunction without changing parts at random.
The principle of operation of the automatic defrost system
The defrost system is a complex mechanism designed to remove ice from the evaporator hidden behind the back wall. In models with No Frost this process runs cyclically. An electronic control module or mechanical timer counts the operating time of the compressor, after which it sends a command to the heater. Defrost heating element turns on and melts the ice, turning it into water, which flows into the pan.
Unlike old models with a “crying” wall, where defrosting occurs naturally when the motor is stopped; active heating is used here. The evaporator temperature should rise above zero, but not overheat the plastic parts of the air ducts. This is monitored by a special defrost sensor (defrost thermostat). As soon as the ice melts, the sensor opens the circuit and heating stops.
If this cycle does not start, the ice builds up, blocking the air circulation channels. The cold stops flowing into the main chamber, although the freezer may continue to freeze. That is why the ability to force start or check this unit is a key repair skill.
Types of defrosting systems and their features
Before climbing inside the unit, you need to determine the type of system. The algorithm of actions depends on this. In modern devices there are three main options for implementing heat removal and moisture removal. Understanding the difference will help you choose the right diagnosis.
The first type is the classic drip system. Here defrosting happens passively. The compressor turns off, the evaporator temperature rises, the ice melts and drips into the groove. In such models there is nothing to “turn off”, you just need to check whether the drainage hole is clogged.
The second type is Full No Frost. There are fans and heating elements here. Defrosting is strictly controlled based on time or sensor readings. The third type is hybrid systems (for example Smart Cooling), where there is a drip system in the refrigeration chamber and No Frost in the freezer. In the last two cases, intervention in the electrical circuit is required to check.
- ❄️ Drip: works automatically when the motor is stopped, does not require separate control.
- 🔥 No Frost: requires forced activation of the heating element through the control module.
- ⚙️ Hybrid: combines both principles, checking is needed for the freezer compartment.
Why is forced defrosting necessary in No Frost?
In the No Frost system, the evaporator is located in a closed box. If the sensor is stuck or the heating element is burned out, the ice will not melt on its own even if the refrigerator is unplugged for an hour. The ice plug is too dense. It requires either complete defrosting (24 hours) or applying voltage directly to the heating element to check its integrity.
Diagnostics of the heating element and defrost sensor
To check whether the system is working, it is often necessary to forcibly apply voltage to the heating element. This is done to prevent malfunction of the heating element itself. If it is intact, but does not heat normally, the problem is in the control module or sensors.
To carry out diagnostics, it is necessary to provide access to the evaporator. Remove the back panel in the freezer compartment. You will see a coil and a tubular heater attached to it. Be careful: Defrost heating element it is fragile and can be easily damaged if handled carelessly. There is also a sensor nearby, which often fails.
⚠️ Attention: Carry out all manipulations with the electrical part only with the refrigerator disconnected from the network! Supplying 220V to the contacts when testing with a multimeter will lead to a short circuit and electric shock.
The test is carried out with a multimeter in resistance measurement mode. The normal resistance of a working heating element varies between 200–400 Ohms, depending on the power and model (for example, for Samsung or Atlant the values may differ). If the device shows “infinity” (open circuit) or “zero” (short circuit), the part must be replaced.
☑️ Checking the defrost circuit
How to start defrosting through the service mode
Many modern brands, such as LG, Samsung, Whirlpoolhave a built-in service mode. This is a software way to enable defrost without disassembling half the case and without applying voltage directly to the wires. This is the safest method for checking the operation of the control module.
A combination of buttons on the control panel is usually required to enter the service mode. For example, simultaneously long pressing the “Freezer” and “Fridge” or “Ice Type” and “Fridge” buttons. The exact combination varies by model and is often hidden from the average user. In this mode, you can switch states: turning on the compressor, fan and, what we need, defrost mode.
In the service menu, specific indicators may light up on the display. For example, certain segments flash or the code “FF” (Freezer Fan) or “dF” (Defrost) appears. The transition between modes is carried out using the temperature control buttons. If, when the defrost mode is activated, you hear a click of the relay on the board and after 10-15 minutes water appears on the evaporator or frost melts, it means that the electronics are working properly.
However, if the control module is “buggy” and does not enter the defrost cycle, the soft start may not work. In this case, you have to use the “old-fashioned” method - direct connection.
Forced activation of the heating element directly
If the service mode is not available or the control module is faulty, the direct voltage supply method is used. This allows you to understand whether the heating element itself is alive and whether the wiring to it is intact. To do this, you will need a 220V power source (carefully!) or use a standard refrigerator plug with “jumpers.”
The essence of the method: disconnect the connector going to the heating element and apply voltage to it directly, bypassing the sensors and the module. If the heating element begins to heat up (this will be visible by the melting of ice or heating of the tube), then it is working properly. The problem lies in the control circuit (defrost sensor, timer or board).
Below is a table with approximate parameters of defrost system elements for popular brands. Please remember that values may vary.
| Brand | Heating element type | Resistance (Ohm) | Sensor response temperature |
|---|---|---|---|
| Samsung | Glass/Aluminium | 210 - 230 | +7...+10°C |
| LG | Quartz/Tubular | 240 - 260 | +5...+8°C |
| Indesit | Tubular (Al) | 350 - 400 | +5...+7°C |
| Atlant | Tubular | 300 - 380 | +5...+10°C |
When applying direct voltage, keep an eye on the time. Do not keep the heating element on for more than 5-10 minutes without control, so as not to melt the plastic air ducts. Wire insulation must be perfect, use only serviceable probes with alligator clips.
Typical faults and their elimination
Why does the defrost system stop working? Most often, it is not the heating element itself that is to blame, but the auxiliary elements. Ice is an aggressive environment, and constant temperature changes destroy contacts. Let's look at the main causes of failures.
First place is taken by defrost sensor. It is a capsule filled with a substance that changes volume at a certain temperature. Over time, it “gets old” and opens the circuit too early (not having time to melt the ice) or too late (overheating the system). Replacing it is the most common repair procedure.
The second enemy is oxidation of contacts in connectors. Moisture penetrates the joints, causing corrosion. The contact disappears, and the control module “thinks” that the circuit is broken and does not issue a heating command. A visual inspection of the connectors often reveals a green coating of oxides.
- 🧊 Ice build-up on the sensor: if the sensor does not fit tightly to the evaporator, it does not sense the real temperature and does not turn on the heating element.
- 🔌 Wiring break: wires can rub against the edges of the metal box or burn out in place soldering.
- 📟 Board failure: The defrost relay on the control module has “burned out”, the board needs to be re-soldered or replaced.
⚠️ Attention: If you find that the insulation of the wires has melted, in no case is it easy twist them and do not insulate them with electrical tape. The high temperature of the heating element will melt the insulation again. Use only heat-resistant casings and heat-resistant wires.
It is also worth mentioning the mechanical defrost timers in older models (for example, some Stinol or Biryusa). They have a motor and contacts inside. If the motor burns out, the timer gets stuck in the "cool" mode and never switches to "defrost". You can check it by turning the timer rod clockwise manually (with the refrigerator turned off). If, after a click, defrosting starts after a while, the timer is faulty and requires replacement.
FAQ: Frequently asked questions
Is it possible to permanently turn off defrosting and use the refrigerator without it?
Theoretically, it is possible, but this will lead to rapid failure of the unit. Without defrosting, the evaporator will become coated with ice, the fan will jam, and the cooling capacity will drop to zero. The compressor will work non-stop, trying to gain temperature, and will burn out after a few days or weeks.
Why does the refrigerator not turn on by itself after defrosting?
Perhaps the thermal protection of the compressor has tripped or the start-up relay is faulty. The cause may also be sticking contacts of the defrost timer (it is “stuck” in defrost mode). Try unplugging the refrigerator for 15-20 minutes, then plugging it back in. If this does not help, you need to diagnose the timer or board.
How often should defrost occur in a working refrigerator?
Depending on the model and load, the defrost cycle in the No Frost system starts every 8-16 hours of compressor operation. This process usually lasts 15–30 minutes. If you notice that the refrigerator is “silent” (does not click or hum) for too long, the cycle may be broken.
Is it possible to replace the defrost heating element with an analogue with a different power?
It is extremely undesirable. Installing a heating element of lower power will lead to incomplete melting of the ice and the growth of a “fur coat”. Installing a more powerful heating element may melt the plastic evaporator tray or damage the sensors. Use only original spare parts or proven analogues with identical parameters.
What does a flashing defrost indicator on the panel mean?
A flashing indicator (often in the form of a snowflake or the letters dF) indicates that the system has detected an error in the defrost cycle. This could be a break in the heating element, a malfunction of the sensor or timer. In some models (for example, LG) this may also indicate a problem with the evaporator fan.