The appearance of ice on the back wall of the refrigeration chamber or the complete absence of cold when the compressor is running often indicates a malfunction systems No Frost. In such situations, the first suspect is the heating element, which has ceased to perform its function of defrosting the evaporator. If you notice that your Indesit or LG has begun to freeze worse, and frost is visible inside the chamber, most likely, diagnostics of the heating element is required.
The verification process does not require deep engineering knowledge, but does imply compliance with safety precautions and the availability of basic tools. Before disassembling the unit, you need to understand the principle of operation: Defrost heating element it turns on on a timer and melts the ice on the evaporator, after which the water flows into the drain. If this does not happen, the air circulation is blocked by an ice plug, and the cold stops flowing into the chamber.
In this article we will look in detail at how to identify a malfunction, which multimeter readings are considered normal, and which indicate a breakdown. You will learn to distinguish a burnt-out heater from problems with a sensor or timer, which will save your budget on calling a technician. Correct diagnosis is half the successful repair of household appliances.
⚠️ Attention: carry out any work on diagnosing the electrical equipment of the refrigerator only after completely disconnecting the device from the electrical network. Residual voltage or accidental switching on can lead to electric shock.
Symptoms of malfunction and preparation for diagnosis
Before picking up a multimeter, it is worth visually assessing the condition of the refrigeration chamber. The main symptom of failure defrost heater is the formation of a “fur coat” or block of ice on the back wall, even if you defrost regularly. There should be no ice in the systems at all; its presence indicates that the defrost cycle does not start or is ineffective. No Frost There should be no ice at all; its presence indicates that the defrost cycle does not start or is ineffective.
Another indirect sign is the constant operation of the compressor without turning off. Trying to compensate for the lack of cold due to the evaporator clogged with ice, the motor wears out. You may also notice that the temperature in the freezer is normal, but in the refrigerator the food is starting to spoil. This is a classic picture of air circulation problems.
To carry out diagnostics, you will need a minimum set of tools. First of all, you need multimeter (tester) capable of measuring resistance and checking the integrity of the circuit. Also prepare screwdrivers for removing panels, a hair dryer for faster defrosting (if ice prevents access) and, possibly, pliers.
Make sure you have free space to work with. The refrigerator will have to be moved away from the wall, and in some models even partially dismantled or placed on its side (although the latter is not recommended for units with linear compressors). Access to the heating element is usually located in the freezer behind a plastic panel.
Removing the heating element and accessing the heater
The process of gaining access to the heating element varies depending on the model and brand. In most modern refrigerators, such as Samsung, Beko or Atlant, the heating element is hidden behind the back wall of the freezer compartment. You will need to completely defrost the unit if there is ice on the evaporator, otherwise you may damage the plastic housing or the evaporator itself when removing the panel.
First remove all shelves, drawers and runners in the freezer. Then carefully unscrew the screws securing the rear plastic panel. Often the screws are hidden under decorative plugs or located inside the camera. Proceed with caution, as plastic becomes brittle in the cold and can crack with sudden movement.
After removing the panel, you will see the evaporator (radiator) and the heating element located next to it. It may appear as an open coil, a U-tube, or be sealed into an aluminum profile. Your task is to disconnect the wires going to the heater contacts. Before doing this, be sure to take a photo of the connection diagram or mark the wires with a marker.
☑️ Preparation for dismantling the heating element
⚠️ Attention: do not try to pick out the ice with a knife or sharp objects. Damage to the evaporator tubes will lead to freon leakage, which will make further repairs economically unfeasible.
Disconnect the connector or terminals going to the heating element. In some models, the wires may be twisted and insulated with electrical tape; in this case, they must be carefully unwound. Now the heating element has been removed or released for testing, and you can proceed to measurements.
Tools and setting up a multimeter
For high-quality diagnostics, a digital multimeter is required. Analog dial testers are also suitable, but a digital device gives more accurate readings and is easier to use. Switch the multimeter control to the resistance measurement mode, which is indicated by the symbol Ω (Ohm).
Select the measurement limit. The range 2 kOhm (2000 Ohm) or 20 kOhmis usually suitable for checking the heating element. If you're limited by the power of your heater, start with a higher range so as not to overload the device, although this is rare for household heating elements. Before measuring, short-circuit the probes to each other - the device should show zero or a value close to zero, which will confirm the serviceability of the probes and battery.
Also, the multimeter has a “dialing” mode, indicated by a speaker or sound wave symbol. In this mode, the device emits a squeak when the circuit is closed. This mode is convenient for quickly checking for an open circuit, but to accurately determine the state of the resistance, it is better to use the Ohmmeter mode.
Make sure that the contacts of the heating element and the multimeter probes are dry and clean. Oxidation or moisture can distort the readings, giving the false impression of resistance where there is none, or vice versa. Wipe the contacts with a dry cloth before starting measurements.
Step-by-step instructions: how to ring the heating element
Now that the instrument is ready, let's proceed to the most important stage. Take the multimeter probes and apply them to the two contacts of the heating element. It doesn’t matter which probe you apply to which contact, since we measure active resistance, which does not depend on polarity.
Look at the device screen. If the heating element is working properly, you will see a specific numerical resistance value. For standard refrigeration heating elements with a power from 150 to 400 W, a resistance in the range from 100 to 400 Ohmis considered normal. The exact value depends on the power and design of your heater.
Formula for calculating resistance
If you know the power of the heating element (indicated on the body), you can calculate the expected resistance using the formula R = U² / P. For example, for a heating element of 300 W at a voltage 220 V: 220 * 220 / 300 ≈ 161 Ohm. A deviation within 10-15% is acceptable.
If a unit on the left (infinity) is displayed on the multimeter screen or the device is silent in dialing mode, this means an open circuit. The nichrome spiral inside has burned out, and current does not flow through it. Such a heating element can only be replaced, it cannot be repaired.
There is another critical test - checking for breakdown on the housing. Press one probe to any contact of the heating element, and the second to the metal body of the heater (clean the small contact area if there is oxidation or paint). The device should show infinity. If you see any resistance values or hear a squeak, the heating element is “broken” to the housing. Use it is strictly prohibitedas it is deadly.
| Multimeter reading | What does this mean | Actions |
|---|---|---|
| 100 – 400 Ohm | Norm, heating element is working | Look for the cause in the timer or sensor |
| Unit on the left (∞) | Broken spiral (burnt out) | Replacing the heating element with a new one |
| 0 Ohm (or close to 0) | Short circuit inside | Replacing the heating element (rare case) |
| Any value on the body | Insulation breakdown | Urgent replacement, operation is dangerous |
After all measurements have been taken, collect the data. If the heating element shows a break or breakdown, it must be replaced with one similar in power and geometric dimensions. Installing an unsuitable heater can lead to overheating of the plastic or insufficient defrosting.
Diagnostics of related elements of the defrost system
It often happens that the heating element turns out to be working, but the defrost system still does not work. In this case, the “weak link” may be other components. The first on the list of candidates is a defrost sensor (defrost thermostat). It is responsible for turning off the heating element when a certain evaporator temperature is reached.
The sensor is checked in the same way: in a cold state (at temperatures below -5...-10°C) its contacts must be closed (resistance 0 Ohm). If you warm the sensor in your hands or with a hairdryer above +10...+15°C, it should break the circuit (show infinity). If the sensor is “stuck” in the open state, the heating element will never receive a command to turn on.
The second important element is the defrost timer or electronic control module. In older models with a mechanical timer, you can try to set it to defrost mode manually by turning the stem with a screwdriver. If after this the heating element heats up, then the problem was the sticking of the timer mechanism. In modern models with Electronics Control it is better to entrust the diagnosis of the board to a specialist.
It is also worth inspecting the wiring. Compressor vibration and temperature changes over time lead to broken wires or oxidation of contacts in connectors. Carefully inspect the entire circuit from the plug to the heating element for melting, black spots and insulation damage.
Replacing the heater and assembling the refrigerator
If the diagnostics confirmed a malfunction of the heating element, you must purchase a replacement. Search for a part based on the model of your refrigerator or the exact dimensions and wattage of your old heater. Universal heating elements can be adjusted in length, but it is important to maintain the power so as not to overload the wiring or timer.
Install the new heating element in place of the old one, securing it with standard fasteners. Make sure that the heating element does not touch the plastic walls of the chamber or drainage tray if this is not provided for by the design. Connect the wires, securing the contacts securely. If twisting was used, it is advisable to solder it and insulate it with heat-resistant electrical tape.
Before installing the back panel, double-check all connections. Make sure there are no forgotten tools, bolts or pieces of insulation in the chamber. Assemble the evaporator panel, tighten the screws, install shelves and drawers. Now the refrigerator is ready for a test run.
Plug in the appliance. After some time (usually after a few hours of operation) the defrost cycle should start. You may hear a characteristic hissing or crackling sound of melting ice - this is the normal operation of the new heating element. During the day, check that a new ice crust does not form on the back wall.
Why can a new heating element burn out immediately after installation?
Most often this happens due to a faulty defrost sensor, which does not turn off the heating on time, or problems with the timer. Also, the cause may be a power surge in the network or improper installation when the heating element touches conductive elements.
Is it possible to temporarily operate a refrigerator without a heating element?
Technically, the refrigerator will freeze, but after 1-2 weeks the evaporator will become overgrown with ice, the air circulation will stop, and the compressor will work non-stop, trying to gain temperature. This will cause it to break. Operation without a heating element is possible only in emergency cases and requires regular complete defrosting (every 3-5 days).
Which heating element is better: open or sealed in a profile?
Heating elements sealed in an aluminum profile are considered more reliable and safe, since they exclude direct contact of the spiral with air and moisture. They heat the evaporator more evenly. Open spirals are cheaper, but they oxidize faster and can burn out when exposed to moisture.
Is it necessary to change the defrost sensor along with the heating element?
Preventive replacement of the sensor is not necessary if it is in good condition. However, given that it is inexpensive and is a consumable item, many craftsmen recommend replacing the “heating element + sensor” combination as a set to avoid repeated disassembly in six months.
What to do if, after replacing the heating element, ice still appears?
If the heating element and sensor are working properly, the problem may be a loose fit of the door, wear seal, clogged drain hole or control module malfunction. It is also worth checking whether the water drainage channel through which melt water leaves the system is not clogged.