The appearance of ice on the back wall of the refrigerator compartment or lack of defrosting in the freezer compartment of the system No Frost often indicates a malfunction defrost. The central element of this system is a tubular electric heater, or heating element, which is periodically turned on to melt the ice on the evaporator. If this unit fails, the ice stops melting, blocks the air channels, and the refrigerator stops cooling food, although the compressor continues to work.
Before calling a technician or buying expensive spare parts, it is necessary to carry out proper diagnostics. Checking the heating element - this is a procedure accessible even to a beginner with a minimum set of tools, primarily a multimeter. Understanding the principle of operation of the heater and the ability to correctly measure its resistance will help you avoid unnecessary expenses and accurately determine the cause of the breakdown.
In this article we will look in detail at how to find the heater, which multimeter readings are considered normal and which indicate a malfunction, and why replacing a burnt-out element requires compliance with strict safety rules.
Symptoms of a malfunctioning heating element
The first sign that Defrost heating element has stopped performing its function is the uncharacteristic behavior of the refrigerator. In systems with automatic defrosting, ice should not accumulate in large quantities. If you notice that the back wall of the refrigerator compartment is covered with a “fur coat” of snow, and in the freezer an ice crust prevents the drawers from closing, this is an alarming signal.
Often a breakdown is accompanied by the fact that the compressor works almost without stopping, trying to compensate for the lack of cold due to air ducts clogged with ice. At the same time, it may be warmer inside the chambers than set on the thermostat. It is also worth paying attention to the presence of water under the refrigerator or on the kitchen floor - this may be a consequence of the drain pan being overfilled due to the fact that the melt water does not have time to drain.
⚠️ Attention: Operating a refrigerator with a defrost that is not working leads to freezing of the fan and its subsequent failure, and also creates an excessive load on the compressor, shortening its service life. services.
Sometimes it is difficult to visually notice the problem if the ice is hidden behind plastic panels. In this case, an indirect sign is a hum or crackling sound coming from the freezer when the fan blades begin to touch the frozen ice.
Preparation for diagnostics and safety precautions
Any work related to the electrical components of the refrigerator requires completely disconnecting the device from the network. Electrical safety —priority number one. Even if you only plan to ring the heating element without removing it, the risk of electric shock if you accidentally damage the insulation or touch live contacts remains high.
To carry out diagnostics, you will need the following set of tools:
- 🛠️ A multimeter (tester) is the main measuring device resistance.
- 🔦 Flashlight - for illuminating hard-to-reach places inside the freezer.
- 🧤 Gloves - to protect hands from sharp edges of ice and plastic.
- 📏 Screwdrivers and pliers - for dismantling protective panels.
Before disassembling, you must completely defrost the refrigerator. If you try to remove the plastic panel covering the evaporator while the ice is still hard, you could damage the fragile plastic or, worse, puncture the aluminum evaporator tubes. Leave the doors open for at least 12-24 hours.
☑️ Checking readiness for repair
After defrosting, remove all shelves and drawers to gain access to the back wall of the freezer. Carefully unscrew the fasteners and remove the plastic panel covering the evaporator. It is behind it that the defrost heater is located.
Visual inspection and search for the heating element
The heating element in modern refrigerators is usually a curved metal tube located under the aluminum evaporator or integrated into its design. In some models, for example Indesit or Atlant, the heater can be enclosed in a transparent quartz tube, in others it is an open nichrome element.
Upon careful inspection, pay attention to the condition of the heater itself. If obvious damage is visible, such as swelling, tube ruptures or burn marks, further diagnostics with a multimeter may not be necessary - the element requires replacement. Also check the condition of the wiring going to the heating element: melted insulation or oxidized contacts indicate overheating or a poor connection.
Sometimes the reason for the lack of heating lies not in the heating element itself, but in the defrost thermostat or sensor that sends a signal to turn on the heater. Therefore, a visual inspection should also include checking adjacent elements of the system.
Where exactly is the heating element?
The location may differ in different models. Samsung refrigerators often use a glass heating element built into the bottom of the evaporator. In LG models, the heater can be located around the perimeter. Always check the diagram of your specific model.
If the element is visually intact, we proceed to an instrumental check. It is important to clean the heating element contacts from possible oxide before testing to ensure a reliable connection of the multimeter probes.
Checking the heating element with a multimeter: step-by-step instructions
The most reliable way to determine the performance of the heater is to measure its electrical resistance. To do this, switch the multimeter to resistance measurement mode (Ohm), selecting the limit of 2 kOhm (2000 Ohm). If your device has a “dialing” mode, it will also work, but digital resistance values will give a more accurate picture.
Disconnect the wires from the contacts of the heating element. Touch the multimeter probes to the two heater contacts. Polarity does not matter in this case. Specific numbers should appear on the device screen. For a working heating element with a power of about 200-400 W, which is typical for household refrigerators, the resistance should be in the range from 100 to 400 Ohms.
The following indications are possible:
- 📉 Infinity (1 or OL) —the circuit is broken, the nichrome spiral inside has burned out. Replacement required.
- 📉 Zero or close to zero —short circuit inside the element. This is dangerous and requires replacement.
- 📉 Stable value (for example, 250 Ohms) —the heating element is working, the problem may be in the thermostat, timer or wiring.
It is also necessary to check the breakdown on the case. Press one probe to any contact of the heating element, and the other to the metal tube of the heater. The device should show infinity. If the multimeter shows any resistance, it means that the insulation is broken, and it is strictly forbidden to use such a heating element - there is a risk of electric shock.
Table of typical values and faults
For ease of diagnosis, we present a table that will help interpret the results obtained depending on the type of heater and the declared power. Remember that the values may vary slightly depending on the ambient temperature.
| Heating element type | Power (W) | Normal resistance (Ohm) | Probable cause of failure |
|---|---|---|---|
| Open (spiral) | 250 | 180 - 220 | Burnout of the spiral |
| Quartz (in glass) | 350 | 130 - 160 | Destruction of the filament |
| Aluminum (in housing) | 400 | 110 - 140 | Corrosion or break |
| Any type | - | Infinity | Complete failure |
If the resistance of the heating element is significantly higher than normal, but not infinite, this may indicate partial burnout of the coil or poor contact inside the terminal box. In the long term, it is better to replace such an element, since its operation will be ineffective.
Do not forget that even a working heating element will not turn on if the defrost thermostat is faulty. This small sensor monitors the temperature of the evaporator and closes the heater circuit only when it is really necessary.
Replacing the heating element and assembling the system
If diagnostics showed that the heater is faulty, it must be replaced. The replacement process depends on the design of your refrigerator. In some models, the heating element is simply inserted into the grooves, in others it is secured with clips or screws. Act carefully so as not to damage the fragile evaporator.
When installing a new element, make sure that it fits snugly