When ice crust begins to accumulate on the walls of the chamber or under the vegetable drawers, and the refrigerator stops freezing normally, the No Frost system is often the culprit. At the center of this system is Defrost heating element a tubular electric heater, which, at the command of a timer or electronic unit, melts the ice on the evaporator. If this element burns out, the ice stops melting, the air channels become clogged, and cold air simply stops flowing into the refrigeration compartment.
Before calling a technician or buying a new unit, it makes sense to carry out diagnostics yourself. Multimeter is a universal device that can be found at many home craftsmen, and it allows you to accurately determine the integrity of the heating element. Understanding the principle of operation and the correct sequence of actions will help you save time and money by returning the equipment to full operation.
In this article we will look in detail at how to correctly get to the heater, what resistance values are considered normal and what to do if the device shows an open circuit.
Symptoms of malfunction and preparation for diagnostics
It is possible to determine that the heating element has stopped heating not only by ice, but also by indirect signs. Often users notice that the refrigerator works almost non-stop, trying to gain temperature, or the compressor hums continuously. Models with a display may display error codes indicating problems with the defrost system. For example, for Samsung this may be an error 21C or 22C, and for LG - Er SF.
However, a visual inspection of the evaporator gives the most accurate picture. If you get to the radiator and see that it is completely or partially covered with a “coat” of ice, although the defrost timer should have started heating, this is the first sign of a problem. It is also worth paying attention to the condition of the heating element itself: sometimes swelling, cracks on the tube or obvious traces of melted insulation are visible.
⚠️ Attention: Start any work on diagnosing and repairing the refrigerator only after completely disconnecting the device from the electrical network! Unplug the plug from the socket to eliminate the risk of electric shock or short circuit.
To carry out diagnostics, you will need a minimum set of tools. First of all, this is a digital multimeter capable of measuring resistance in the range of up to 20 kOhm. You may also need screwdrivers (Phillips and flathead), a hair dryer to speed up defrosting (if there is a lot of ice) and, possibly, pliers for removing terminals.
- 🔍 Digital multimeter with working probes
- 🪛 Set of screwdrivers of different sizes
- 🌡️ Construction or household hair dryer for defrosting
- 🧤 Protective gloves for working with sharp edges
Access to the heating element: disassembling the freezer
To check the heating element, you must first find it and gain physical access to it. In most No Frost refrigerators, the heating element is hidden behind the back panel of the freezer. The disassembly process may vary depending on the brand, but the general algorithm is similar for most models, such as Indesit, Beko or Atlant.
First you need to completely defrost the refrigerator. Even if you think there is not much ice, any remaining water inside may leak onto the electronic modules or wiring when the panels are removed. Leave the doors open for at least 12-24 hours. It is not recommended to speed up the process with boiling water, since a sudden temperature change can damage the plastic evaporator box.
After defrosting, remove all shelves, drawers and guides in the freezer compartment. Then remove the rear plastic panel. It can be attached with screws, which are sometimes hidden under decorative plugs, or held on with plastic latches. Act carefully so as not to break the fragile plastic in the cold.
Difficulties in removing the panel
If the panel cannot be removed, do not use force. Check that all screws are removed and that there are no hidden fasteners on the bottom or sides. Sometimes the panel gets stuck with residual ice - in this case, carefully warm the joints with a hairdryer.
When the panel is removed, you will have a view of the evaporator. The heating element is usually located at the bottom of the radiator, under it, or built into special grooves. It is a curved metal tube with two wires attached to it. In some models, for example, in old Stinol or Samsung, the heating element can be enclosed in an additional protective casing or aluminum profile.
Multimeter testing technology
The most important stage is the direct measurement of the heater parameters. The multimeter is switched to resistance measurement mode (indicated by the symbol Ω, Omega). The range is selected 2 kOhm or 20 kOhm, since the resistance of a working heating element usually ranges from 200 to 700 Ohms.
Disconnect the terminals power supply from the contacts of the heating element. If the wires are tight, you can carefully remove them by gently shaking them from side to side. Do not pull on the wires themselves to avoid breaking them at the base. Touch the multimeter probes to the two heater contacts. The polarity is not important here, since we are checking the active resistance.
☑️ Algorithm for checking the heating element
If one (infinity) or a value close to zero is displayed on the device screen, this indicates a malfunction. One means open circuit —the nichrome spiral inside has burned out. Zero or a very small value (1-5 Ohms) indicates a short circuit of the turns, which is less common, but also requires replacing the element.
⚠️ Attention: Before checking, make sure that the contacts of the heating element and the multimeter probes are dry. Water that gets on the contacts can distort the readings, creating a false circuit and showing resistance where it should not be.
It is also critically important to check the heating element for breakdown to the body. This is a situation where the insulation between the heating coil and the metal tube is broken. One probe is applied to any contact of the heating element, and the second is applied to the metal tube of the heater or to the ground of the refrigerator. The device should show infinity (1). If any resistance value appears, it is dangerous to operate such a heating element - this can lead to an electric shock when touching the body of the refrigerator.
Resistance standards and table of values
Understanding what numbers should be on the multimeter screen will help to avoid mistakes. Resistance directly depends on the power of the heating element and its design. Standard values for household refrigerators vary within a certain range. If your measurements differ greatly from those in the table, the element is most likely faulty.
Below is a table with approximate resistance values for various types of heaters. Remember that the permissible measurement error is about 5-10%.
| Heating element type | Power (W) | Resistance rate (Ohm) | Measurement verdict |
|---|---|---|---|
| Open (S-shaped) | 300 - 400 | 150 - 250 | Good |
| Heating element in aluminum profile | 400 - 600 | 180 - 320 | Good |
| Any type of heating element | - | ∞ (Unit) | Open (Faulty) |
| Any type of heating element | - | 0 - 10 | Short circuit of turns (Faulty) |
| Check for body | - | Any value | Insulation breakdown |
If your heating element consists of two sections connected in series (often found in long evaporators), it may have three contacts. In this case, the resistance between the extreme contacts should be the sum of the resistances of each section. You need to check in pairs: first-second, second-third and first-third.
Replacing the heating element
If diagnostics showed a break or breakdown, the only way out is replacing the heating element. Repairing a burnt-out nichrome spiral at home is neither possible nor practical. The new element is selected according to power, geometric dimensions and type of fastening. You can find original spare parts or universal analogues that are customized locally.
Removing the old heating element is usually simple: it is either inserted into the grooves of the evaporator or secured with brackets. Carefully remove it, being careful not to damage the aluminum evaporator tubes - they are very thin and easily pierced. When installing a new element, proceed with caution. If the heating element is universal and requires bending, do it smoothly, without sharp bends, so as not to damage the internal spiral.
After installing the new heater, reassemble the structure in the reverse order. Make sure all wires are securely fastened and do not touch moving fan parts or sharp metal edges. Turn on the refrigerator and check the first defrost cycle, if possible, or simply monitor the temperature rise.
⚠️ Attention: When installing the heating element, make sure that it fits tightly to the surface of the evaporator or is in a special groove. The air gap between the heater and the ice (or surface) drastically reduces the efficiency of defrosting.
Frequent errors and additional checks
Sometimes replacing the heating element does not solve the problem, and the ice continues to grow. This suggests that it is not the heater itself that is faulty, but the control circuit. Before committing to a new heating element, it is worth checking other elements of the No Frost system. Often the culprit is defrost sensor (defroster), which does not give a command to turn on the heating, or a timer that is “stuck” in cooling mode.
It is also worth checking the integrity of the wires going to the heating element. Under constant cycles of freezing and defrosting, wire insulation can crack and contacts can oxidize. Ring the circuit from the connector to the heating element itself. If the multimeter shows a break in the wires, they need to be replaced or restored.
- 🔌 Check the connectors for oxidation and reliability of contact
- 🌡️ Test the evaporator temperature sensor
- ⏱️ Make sure the defrost timer or electronic module is working properly
- 🌀 Check the operation of the evaporator blower fan
Do not forget that modern refrigerators are complex electronic devices. If you have replaced the heating element, sensors and checked the wiring, but the error on the display does not disappear, you may need to reset the error through the service menu or diagnostics main board. In such cases, without specialized equipment and knowledge of circuit design, it is better to contact a service center.
Regular maintenance of the refrigerator, including cleaning the drainage hole and checking the seals, will extend the life of the defrost system. A clean evaporator and proper ventilation contribute to the uniform distribution of cold and reduce the load on the heating elements.
Is it possible to temporarily use a refrigerator with a faulty heating element?
Technically, the refrigerator will work, but only in static cold mode. Over time, the evaporator will be completely covered with ice, blocking the channels. The cold will stop flowing into the chamber, the food will begin to deteriorate, and the compressor will wear out, trying to compensate for the lack of cold. Operation in this mode is only permissible for a short time while you are waiting for spare parts.
Why does a new heating element burn out after a short time?
A common cause is a faulty defrost sensor or timer. If the sensor is “stuck” and does not turn off the heating, the heating element works too long, overheats and burns out. Also, the cause may be poor contact in the terminal block, causing sparking and local overheating.
Is it necessary to lubricate the heating element with thermal paste during installation?
In most household refrigerators, the heating element is installed “dry” or in grooves with an aluminum profile. The use of thermal paste is not required by manufacturers, but in some cases (poor contact with the surface) a thin layer of heat-resistant compound can improve heat transfer. The main thing is not to use ordinary lubricants, which will dry out or catch fire.
Which heating element is better: open or in an aluminum profile?
Open heating elements (in the form of a curved tube) heat up and cool faster, but are more susceptible to mechanical damage. Heating elements in an aluminum profile (cassette) are more durable, transfer heat better due to the larger contact area, but are more expensive and more difficult to install. It is better to use the type that is provided for by the design of your refrigerator.
What to do if the multimeter shows different values for each measurement?
Unstable readings may indicate poor contact of the probes with the terminals of the heating element (oxidation) or internal destruction of the spiral, which manifests itself during vibration. Clean the contacts with fine sandpaper and repeat the measurement, pressing the probes tightly. If the readings “dance”, it is better to replace the element.