The situation when, when trying to start the refrigerator, the machine knocks out shield is not just a household inconvenience, but a signal of a serious electrical circuit malfunction. This indicates that leakage current or the short circuit has reached critical values that are dangerous for the wiring. This symptom cannot be ignored, since turning on the machine again without eliminating the cause can lead to a fire.
Most often, the problem lies in the breakdown of the insulation of heating elements or electric motor windings. Moisture, condensation and time destroy the protective layer of wires, creating direct contact with the device body. It is to this contact that the residual current device (RCD) or differential circuit breaker reacts, breaking the circuit.
Before proceeding with detailed diagnostics, it is necessary to exclude external factors: network overload by other powerful consumers or a malfunction of the circuit breaker itself. However, if it knocks out exactly at the moment the compressor starts or the defrost mode is turned on, the problem is localized inside the unit. Next, we will analyze the main components that trigger the protection.
Breakdown of the defrost heating element as the main cause
The most likely culprit for the operation of the machine in refrigerators with the system No Frost is the defrost heater. This element operates in an aggressive environment: constant heating and cooling cycles combined with high humidity lead to microcracks in the protective shell of the heating element. When moisture gets inside, a breakdown occurs on the body.
Unlike conventional incandescent lamps, heating elements in refrigerators are often made in the form of glass tubes or open spirals, which makes them vulnerable. When the defrost timer is turned on, voltage is applied to the heater, and if the insulation is broken, the current goes not to heating, but to grounding (the housing), which fixes the machine.
⚠️ Attention: Do not try to insulate a broken heating element with electrical tape or sealant. The heating in the work area is too great, and any insulating material will quickly deteriorate, which will lead to a repeated short circuit or fire.
To check the heater, it must be “ringed” with a multimeter in resistance measurement mode. One probe is placed on the contact of the heating element, the other on the metal body or flange. If the device shows at least some resistance (even a few megaohms), the element is faulty and requires replacement.
How to check the heating element without a multimeter?
Visually inspect the heater tube. If swelling, blackening or obvious cracks are visible on the glass, the element is guaranteed to be broken. Also, a sign of a malfunction may be a characteristic burning smell or melted plastic around the heating element mounts.
Malfunctions of the motor-compressor
The second most common reason for knocking out plugs is itself motor-compressor. Inside the sealed casing there are electric motor windings, which can overheat during long-term operation. Overheating leads to the destruction of the varnish insulation of the wires, as a result of which the turns close to each other or to the housing.
This especially often happens in older models or when working in conditions of insufficient ventilation. If the compressor hums, but does not start, and the machine immediately knocks out, most likely an interturn short circuit has occurred. The starting current at this moment exceeds the nominal value many times, which instantly causes a protection reaction.
Diagnostics of the compressor requires caution. It is necessary to remove the start-up relay and check the resistance between the winding contacts and the housing. Normal resistance should tend to infinity. Any value other than infinity indicates a breakdown.
Problems with the starting relay and wiring
The starting relay is a small but critical component that provides an impulse to start the engine. There are contacts inside the relay that can burn or stick if switched frequently. If the relay contacts stick when closed, the compressor does not receive the correct start signal, which can cause current surges.
In addition, it is worth paying attention to the internal wiring of the refrigerator. Vibration during compressor operation wears down the insulation of wires over time, especially where they pass through metal partitions or near the motor. A bare wire touching the housing creates a direct short circuit.
When inspecting the wiring, look for traces of melted plastic, blackening, or the characteristic smell of burnt insulation. Often the problem is hidden in the place where the cable enters the compressor or near the lighting lamp if it is poorly located.
☑️ Diagnostics of wiring and relays
The influence of humidity and condensation
Moisture - the main enemy of electrical appliances. If the refrigerator is not sealed properly or the door is opened frequently, excess condensation will form inside. Water can flow down the walls of the chamber and get on electrical contacts, lamp sockets or terminal blocks.
The accumulation of water in a niche for a lighting lamp or in a drainage tray is especially dangerous if electrical elements pass there. Water containing salts and minerals is an excellent conductor of current. When it hits the phase wire and the housing, it creates a conductive bridge.
In such cases, the machine may not knock out immediately, but periodically, for example, only after defrosting or in damp weather. The solution to the problem lies in eliminating the source of moisture: replacing the door seals, cleaning the drainage hole and thoroughly drying the internal components.
⚠️ Attention: Before any drying work, make sure that the refrigerator is unplugged for at least 24 hours. Moisture inside the thermal insulation or on the contacts can remain for a long time and lead to an electric shock the first time you turn it on.
Fault diagnosis table
To simplify troubleshooting, use the summary table of symptoms. It will help narrow the search to a specific node.
| Symptom | Probable cause | Level of difficulty of repair |
|---|---|---|
| Knocks out immediately when plugged in | Short circuit in the cord, plug or internal wiring | Low |
| The machine operates after 10-20 minutes of operation | Breakdown of the defrosting heating element (beginning of the defrosting cycle) | Medium |
| Audible beep, then click and the machine knocks out | Malfunction of the start relay or compressor wedge | Medium/High |
| Tripping occurs in wet weather | High humidity, condensation on contacts | Low (drying) |
The procedure for detecting a malfunction
If you encounter the described problem, the algorithm of actions should be clear and safe. The first rule: do not turn on the machine repeatedly. Each switching on of a faulty appliance creates a risk of damaging the wiring in the wall.
It is necessary to turn off the power to the refrigerator completely by unplugging the plug from the socket. Then you should visually inspect the available nodes. If there are no external signs (smoke, smell, sparks), instrumental diagnostics using a multimeter is required.
If a breakdown of the heating element or relay is detected, these parts must be replaced. If the problem is in the compressor, repair is often not economically feasible, since it requires replacing the engine, evacuation of the system and refilling with refrigerant.
Prevention and operational safety
To avoid a repetition of the situation, it is important to monitor the condition of the refrigerator. Regular defrosting (if the model is not No Frost), checking the integrity of the seals and cleaning the rear grille from dust will prolong the life of the electrical appliance.
It is also worth paying attention to the quality of the electrical network. If voltage surges frequently in your home, use a stabilizer. Sudden voltage surges can break through the insulation of even serviceable elements.
Do not overload the network by plugging the refrigerator into the same outlet as a microwave oven or electric kettle. The total power of these devices may exceed the permissible load on the machine, causing it to operate even without a malfunction of the refrigerator itself.
Is it possible to temporarily use the refrigerator if the machine breaks down?
Absolutely not. Operating a device with a puncture to the housing is deadly. Even if you use an extension cord or another circuit breaker, the risk of electric shock when touching the metal parts of the refrigerator remains extremely high.
Why does the RCD knock out, but not a regular circuit breaker?
The RCD reacts to current leakage (the difference between the incoming and outgoing current), which indicates an insulation breakdown. A conventional machine only trips when there is an overload or short circuit. If the RCD knocks out, it means that the current “goes” to the housing, which is a sign of a malfunction of the device.
How much does it cost to replace a defrost heating element?
The cost of the heater itself usually ranges from 500 to 2000 rubles, depending on the model of the refrigerator. The replacement work takes about 1 hour and can cost an additional 1,500 rubles. Self-replacement is cheaper, but requires disassembly skills.
What to do if after replacing the heating element the problem remains?
If replacing the heater did not help, you need to check the control circuit (timer or board) and the wiring going to the heating element. Perhaps the breakdown occurs at the junction of the wires or in the control unit itself.