The situation when you turn on the network or during work the refrigerator knocks out the circuit breakeralways takes you by surprise. This is not just a household inconvenience, but a signal of a serious electrical equipment malfunction, which, if ignored, can lead to a fire or failure of all wiring in the apartment. Modern protective devices, such as RCDs or differential circuit breakers, react to the slightest current leakage, so the problem lies in insulation failure or short circuit.
Before calling a technician, it is useful to understand the nature of the problem that has arisen. Most often, the protection is triggered due to a breakdown on the housing of one of the powerful energy consumers inside the unit. This could be a motor-compressor, a heating element, or even wiring installed inside the housing. Understanding which particular unit is faulty will allow you to make the right decision: repair the appliance or prepare to buy a new one.
In this article we will analyze in detail all the possible reasons why automatic switch reacts when the refrigerator is turned on. We will consider both complex electrical faults and banal operating errors that can be easily corrected independently without special tools.
Breakage of the defrosting heating element as the main cause of leakage
The most common reason why knocks out the RCD or automatic when the refrigerator is turned on defrosting, is a malfunction of the defrosting heating element. In models with the No Frost system, this element is heated cyclically to melt ice on the evaporator. Over time, the metal tube of the heating element can burn out, and the water formed when the ice melts gets onto the contacts, creating a path for leakage current.
The insidiousness of this breakdown is that the refrigerator can freeze normally and work for hours, but the machine knocks out only at the moment the defrost cycle starts. The owner often does not connect these events until the leak becomes critical. Water flowing into the pan closes the circuit to the grounded housing, which is instantly recorded by the protective automation.
This problem can be diagnosed by removing the heating element from the circuit. To do this, you need to remove the back panel in the freezer and visually inspect the heating element. If the tube shows swelling, cracks or obvious signs of corrosion, replacement is inevitable. It is also worth checking defrost sensorwhich can stick in the "on" position.
How to check the heating element with a multimeter?
For an accurate diagnosis, disconnect the wires from the heating element and switch the multimeter to resistance measurement mode (Ohms). If the element is working properly, the device will show a value from 200 to 500 Ohms. If the resistance is infinitely high, the spiral is broken; if it is close to zero, a short circuit has occurred. Also check the resistance between the heating element body and the terminals: the device should not show any values (the dialing mode is silent).
⚠️ Attention: If you find that the heating element is broken, under no circumstances try to isolate the damaged area with electrical tape. The heating element operates in an aggressive, humid environment, and any insulation will quickly become unusable, which will lead to a re-circuit and the risk of electric shock.
Replacing a heating element is not a complicated procedure, but requires care. It is important to install the new element correctly and ensure the connections are tight so that condensation does not get back onto the contacts. After replacement, it is recommended to monitor the behavior of the machine for several cycles of operation.
Malfunctions of the motor-compressor and start relay
The second most common reason for knocking out plugs is itself motor-compressor. This is the heart of the refrigerator, and if an interturn short circuit occurs in its windings or an insulation breakdown occurs on the housing, the current increases sharply. The automatic switch detects the jump and opens the circuit, saving the wiring from overheating.
Often the problem lies not in the motor itself, but in the start-protection relay. This small block is responsible for starting the engine. If the contacts inside the relay are burnt or stuck, the compressor cannot start, hums and consumes a huge starting current. At this moment the protection is triggered. The malfunction can be determined by a characteristic click and a subsequent hum, which lasts several seconds before the machine is knocked out.
It is also worth paying attention to the condition of the wiring going to the compressor. In older models, the wire insulation dries out over time and cracks from vibration and heat. If a bare wire touches the metal body of the compressor or the frame of the refrigerator, an instant short circuit occurs.
☑️ Compressor diagnostics
If the diagnostics showed that the relay is working properly and the wires are intact, but when connecting the compressor directly (bypassing relay) the machine still knocks out, then, alas, the engine has failed. Repairing such a unit is usually impractical; it is simpler and more reliable to replace the entire compressor.
Problems with wiring and internal connections
Do not discount the condition of the internal electrical wiring of the refrigerator. During operation, especially during defrosting or mechanical stress, the wires may fray. Often the insulation is broken where cables pass through metal partitions or near sharp edges of the housing.
Moisture is the main enemy of electrics. If your refrigerator has a leak or the drainage system is clogged, water may leak into the electrical connections. Even a small amount of water on a terminal block or plug can create a conductive bridge sufficient to trip a sensitive RCD RCD.
Particular attention should be paid to the plug and power cord. If they melt, turn black, or show signs of sparking, that could be the problem. Poor contact in the socket also causes the plug to heat up, which leads to destruction of the insulation and subsequent short circuit.
| Symptom | Probable cause | Test method |
|---|---|---|
| The machine knocks out immediately when turned on plugs | Short circuit in the cord or plug | Visual inspection, continuity of the circuit |
| Tripping after a few hours of operation | Breakdown of the defrost heating element or thermostat | Exception nodes from the circuit one by one |
| Knocks out only when the engine starts | Malfunction of the starting relay or compressor | Measuring the starting current, checking the relay |
| Periodic shutdowns without obvious cyclicity | Poor wiring insulation, moisture ingress | Careful inspection of the wiring harnesses |
The influence of humidity and condensation on electronics
Modern refrigerators are full of electronics: control modules, displays, sensors. The control board is a complex electronic device that is sensitive to humidity. If excess condensation has formed in the fridge compartment or a leak has occurred, water can get onto the board, causing a short circuit in the tracks.
Moisture promotes oxidation of contacts and the formation of conductive salt deposits. Even if there is no visible water, high humidity inside the housing (especially in the compressor niche) can reduce the insulation resistance to critical levels. In such cases differential automatic machine reacts to leakage currents, which in a dry state would be within normal limits.
Often the problem lies in improper operation. For example, if you often open a door in hot weather, a lot of condensation will form on the interior walls and elements and flow down. If the drain hole is clogged, water accumulates and reaches the electrical components.
If you suspect moisture ingress, you must completely unplug the refrigerator and leave it open for a day to dry completely. Sometimes this helps to temporarily restore functionality, but searching for the source of water ingress is required.
Malfunctions of the thermostat and other sensors
A thermostat (thermostat) is a device that opens and closes the compressor power circuit depending on the temperature. There are contacts inside it that can burn or stick over time. If the thermostat housing is touched or moisture gets inside, a breakdown may occur on the housing, which will trigger the protection.
A similar situation can arise with temperature sensors (NTC thermistors). Although they operate at low currents, their wiring is often located near power lines. Damage to the insulation of thin sensor wires can lead to a short to ground. In modern models with a system Full No Frost there may be several such sensors, and each of them is potentially the source of the problem.
It is difficult to determine a faulty sensor or thermostat without a circuit and instruments. However, if the machine is knocked out at the moment when the refrigerator should turn off or turn on according to the temperature, it is worth checking these elements first.
Self-diagnosis algorithm
If you decide to find the cause yourself, act methodically. The main safety rule: carry out all work only with the device completely disconnected from the network. Start with a visual inspection. Check the plug, socket (plug in another powerful device to make sure the apartment's wiring is working properly), refrigerator cord.
Then proceed to internal diagnostics. Remove the back cover in the freezer and inspect the defrost heating element. Remove the bottom panel (where the compressor is), check the wires and relay condition. If no visual defects are found, you can try the elimination method: turn off the consumers (heating element, compressor, fan) one by one and plug the refrigerator into the network. That element, when turned off, the machine will stop knocking out, is the culprit.
However, if you do not have experience working with electrical appliances, it is better not to take risks. Electricity does not forgive mistakes, and the cost of calling a technician is often lower than buying a new refrigerator or treating the consequences of a fire.
⚠️ Attention: It is strictly forbidden to install circuit breakers with a large rating (for example, instead of 16A, install 25A or 32A) in the hope that they will withstand the load. This is a direct road to a wiring fire, since it is not designed for such currents.
Frequently asked questions (FAQ)
Can an old refrigerator knock out a new machine?
Yes, it can. New machines and RCDs have higher sensitivity and speed. An old refrigerator with worn-out insulation could work for years with old plugs, but a modern sensitive machine will immediately detect a current leak that was simply not noticed before.
Why does the machine only knock at night?
Most likely, this coincides with the defrost cycle, which in many models starts at certain intervals (every 8-12 hours). If the heating element is broken, then during night defrosting a short circuit occurs.
Is it dangerous to continue to use the refrigerator if it sometimes knocks out the machine?
Extremely dangerous. This is a sign that the current is flowing along a path not provided for by the design (to the housing). Touching such a refrigerator can lead to an electric shock, and further operation is guaranteed to lead to complete failure of the equipment or a fire.
Is it possible to remove the grounding so that the RCD stops knocking out?
No, this is deadly! The RCD knocks out precisely because it detects a leak. By removing the grounding or “cheating” the protection, you leave the refrigerator energized. The case will give an electric shock to everyone who touches it.