Sudden defrosting of food in the refrigerator compartment often becomes an unpleasant surprise for the owner. If the compressor works without stopping or, on the contrary, is silent for days, the thermoregulation system is the first to come under suspicion. Thermostat It is the key element responsible for maintaining the set temperature, and its failure paralyzes the operation of the entire unit.
Many users mistakenly believe that the breakdown of this unit is always associated with expiration of the service life of the device itself. However, practice shows that failure is often provoked by external factors, improper operation or hidden defects of adjacent systems. Understanding why the thermostat breakswill help you avoid costly repairs or prevent damage to a large number of products.
In this article we will analyze in detail the mechanical, electrical and operational causes of failures. You'll learn how power surges affect contacts and why a coolant leak can be fatal to a temperature sensor. Competent diagnostics will allow you to determine whether a part needs to be replaced or whether the problem lies deeper.
Mechanical wear and fatigue of materials
The main reason for the failure of thermostats in old and actively used models is the natural wear and tear of internal mechanisms. Inside the device body there is membrane a complex system of springs that are in constant motion. Each cycle of turning the compressor on and off creates microscopic stress in the metal, which accumulates over time.
When the strength resource is exhausted, the spring loses its elasticity or bursts. In this case, the contacts either open forever, or, worse, stick in a closed state. Mechanical fatigue is an irreversible process, depending on the number of actuation cycles included by the manufacturer when designing the unit.
In addition, moving parts may be subject to corrosion if inside the housing moisture got in. This often happens during defrosting when water flows down the walls of the chamber. Oxidation of contacts leads to an increase in resistance and disruption of the conductivity of electric current.
- 🔩 Loss of elasticity of the bellows tube transmitting pressure.
- ⚙️ Deformation of the return spring of the switching mechanism.
- ⚡ Burning or oxidation of the contact group due to sparking.
⚠️ Attention: If the thermostat clicks but does not open the circuit, under no circumstances leave the refrigerator plugged in for a long time. This can lead to freezing of the evaporator and failure of the compressor due to wear and tear.
The influence of power surges on electrical equipment
Electrical components of refrigeration equipment are extremely sensitive to the quality of the supply network. Sudden voltage changes, known as jumps, can break through the insulation or weld the contacts inside the thermostat. Even if the device itself is equipped with protection, frequent fluctuations in the network gradually destroy the structure of the metal contacts.
The phenomenon is especially dangerous when the voltage drops briefly and then increases sharply. At the moment of switching on after a jump, a starting current passes through the thermostat contacts, which is significantly higher than the operating current. If at this moment sparking occurs due to instability of the network, carbon deposits and microfunnels form on the surface of the contacts.
Over time, the effective contact area decreases, which leads to local overheating. Thermal destruction The contact group is one of the most common reasons why the thermostat stops passing current to the compressor. In some cases, the contacts may weld to each other, and the refrigerator will no longer turn off.
To protect equipment, it is recommended to use voltage stabilizers, especially in areas with unstable power supply or frequent thunderstorms. This will extend the life of not only the thermostat, but also the starting relay with the compressor.
Problems with the capillary tube and leakage freon
The design of the thermostat is inextricably linked to the refrigeration circuit through a thin capillary tube. Inside this tube and bellows there is a sensitive filler gas (often the same freon or a special refrigerant). The principle of operation is based on a change in gas pressure with a change in temperature.
If mechanical damage to the tube occurs or the seal of the bellows is broken, the gas evaporates. Without internal pressure, the membrane cannot act on the contacts, and the thermostat “stalls”. This often happens during inaccurate defrosting, when users try to pick out the ice with sharp objects and touch the tube running inside the chamber.
Also the cause may be a factory defect in soldering or microcracks in the metal that have arisen due to vibration of the compressor over many years. In this case, repair is impossible - a complete replacement of the unit is required, since filling the tube with gas at home is technically difficult and economically unfeasible.
| Symptom | Probable cause | Action |
|---|---|---|
| The refrigerator does not turns on | Gas leak from the bellows | Replacing the thermostat |
| The compressor hums, but does not start | Sticking contacts | Cleaning or replacement |
| Continuous operation without stopping | Loss of tightness | Circuit diagnostics |
Improper operation and defrosting
The human factor occupies a significant share in the statistics of breakdowns of household appliances. Aggressive defrosting is the main enemy of the thermostat capillary tube. Using knives, screwdrivers or other sharp objects to chip ice often punctures the tube that runs in close proximity to the evaporator.
Another common mistake is setting the temperature control to maximum cooling in hot weather unnecessarily. This forces the thermostat to work to the limit of its capabilities, reducing the rest time of the compressor and increasing the frequency of contact cycles. Overload the mechanism leads to accelerated wear.
It is also worth mentioning loading the refrigerator with warm foods. A sudden change in temperature inside the chamber creates a stressful situation for the sensor. The thermostat is forced to react to a sharp jump in heat, which can lead to incorrect operation or false alarms of the protection system.
- 🧊 Using a hair dryer or boiling water to speed up defrosting can melt the insulation of the thermostat wires.
- 🌡️ Setting the minimum temperature (+1...+2°C) in the summer makes the mechanism work at extreme mode.
- 🚪 Frequent and prolonged opening of doors disrupts the temperature balance, making the thermostat "nervous."
⚠️ Attention: Never defrost the refrigerator using sharp metal objects. It is better to remove the ice with a plastic scraper or let it melt naturally.
☑️ Check before calling a technician
Factory defects and quality of components
Even modern manufacturers are not immune to the issue defective batches. In the case of thermostats, defects can manifest themselves in the form of poor-quality soldering of the capillary tube, the use of an alloy with low corrosion resistance, or defects in the assembly of the contact group.
Often problems arise after replacing the original thermostat with a cheap analogue. Chinese copies well-known brands may have a shorter working life or incorrect calibration values. This leads to the fact that the refrigerator begins to freeze less easily or, conversely, freezes food, even if the part is visually in good working order.
When buying a new refrigerator, you should pay attention to the brand of the thermostat manufacturer (often this is Danfoss, Thermo, KSD). Well-known brands value their reputation and are less likely to make critical mistakes in production. However, they also have rare cases of factory defects that appear in the first year of operation.
How to distinguish an original from a fake?
Original thermostats have clear markings, smooth body seams and high-quality wire insulation. On cheap analogues, there is often play in the regulator knob and cheap plastic that smells of chemicals.
The influence of the external environment and installation conditions
A refrigerator is a technique that requires certain environmental conditions. Installing the unit in close proximity to heating appliances, stoves or in direct sunlight creates a thermal load. The thermostat, sensing temperature, may not work correctly, since heat from external sources heats the body of the device or the capillary tube.
High humidity in the room also plays a negative role. Condensation that forms on the external parts of the thermostat (especially if it is located outside, as in some old Atlant or Biryusa models) causes oxidation of contacts and corrosion of metal parts. This leads to unstable operation and eventual failure.
In addition, vibration from the floor or a nearby washing machine can be transmitted to the refrigerator body. Constant shaking loosens the internal connections of the thermostat, weakens the fastenings of the capillary tube and can lead to broken contacts or a leak.
⚠️ Attention: Make sure that the refrigerator is level and does not touch walls or furniture. Vibration from the compressor, amplified by improper installation, destroys the internal components of the thermostat.
FAQ: Frequently asked questions
Is it possible to repair a thermostat with your own hands?
In most cases, repairing a thermostat at home is impossible and impractical. The device is a sealed unit, and violation of its integrity (opening) will lead to loss of filler gas. The only thing that can be done is to replace the part with a new one.
How to understand that it is the thermostat that is broken and not the compressor?
If the compressor does not make sounds at all and does not start, but the light in the chamber is on, most likely the problem is in the thermostat or start relay. If the engine hums, tries to start and clicks, but does not start, the problem may be in the start relay or the compressor itself. The simplest test: close the thermostat contacts directly (observing safety precautions). If the refrigerator starts working, the culprit has been found.
How long does a thermostat last on average?
The average service life of a high-quality thermostat is 7-10 years or about 10-15 thousand on/off cycles. However, with frequent power surges or improper operation, this period can be reduced to 3-4 years.
Why does the thermostat click but does not turn on the refrigerator?
A click means that the mechanism is trying to work, but there is no contact. This may be due to burnt contacts, broken internal wiring, or loss of gas pressure in the bellows. Also, the cause may be a malfunction of the start relay, which follows the thermostat in the circuit.
Can the thermostat break due to defrosting with boiling water?
Yes, this is very likely. A sudden temperature change can deform the capillary tube or damage the insulation of the wires going to the contacts. In addition, hot water can flow inside the thermostat housing, causing a short circuit or corrosion.