Inside every household refrigerator, a complex physical process occurs that allows you to keep food fresh for a long time. The central element of this system is refrigerant a special working substance circulating in a closed circuit. It is thanks to its properties that heat is removed from the refrigeration chamber and released into the environment.
Many users know this substance under the common name "freon", although technically freons are only one of the groups of refrigerants. Refrigerant able to easily change its state of aggregation: by evaporating, it absorbs a huge amount of thermal energy, and when it condenses, it releases it. Understanding the principles of operation of this substance helps equipment owners quickly diagnose malfunctions and avoid critical errors during operation.
If you notice that the refrigerator has stopped freezing and the compressor is running without stopping, the problem often lies in a circulation disorder or a leak of working gas. Unlike oil in a car engine, coolant is not consumed in the process of normal operation. Its quantity in the system is constant, and if it disappears somewhere, it means that a depressurization of the circuit has occurred, requiring professional intervention.
The principle of operation of the refrigerant in the refrigeration cycle
The operation of the refrigerator is based on a physical law: when evaporating, any liquid absorbs heat. The refrigerant, under pressure created compressor, is forced into the condenser (black radiator on the back or sides of the case). There the gas cools and turns into a liquid state, giving off heat to the kitchen. Further, passing through the capillary tube and evaporator, the pressure drops sharply, and the liquid instantly boils, turning into gas.
⚠️ Attention: The process of boiling the refrigerant inside the tubes evaporator operation occurs at very low temperatures (down to -40°C and below). It is this cold gas that cools the walls of the chamber and the food inside.
The circulation of the substance is continuous as long as the refrigerator is plugged in. The refrigerant gas is drawn into the compressor, compressed, and sent back to the condenser. The efficiency of this cycle directly depends on the properties of the gas used and the tightness of the system. If air or moisture gets into the circuit circulation is disrupted, which leads to compressor failure or capillary blockage.
Modern models of refrigerators, such as Liebherr or Boschuse complex systems refrigerant flow control for maximum energy efficiency. Some models use separate circulation for the freezer and refrigerator compartments, which allows you to set independent temperature conditions.
Main types of refrigerants: from Freon to Isobutane
The history of the development of refrigeration technology knows many different chemical compounds used as a working fluid. For a long time, the standard was chlorofluorocarbons (CFC)known as R-12 freons. They were safe for humans, did not burn, but, as it turned out later, caused colossal harm to the ozone layer of the Earth.
The following types are most often found in modern household refrigerators:
- ❄️ R-600a (Isobutane) - a natural hydrocarbon, which today is the standard for most European and Asian brands. It is environmentally friendly, but explosive when concentrated in air.
- ❄️ R-134a is a hydrofluorocarbon that replaced R-12. It does not deplete the ozone layer, but has a high global warming potential. Often used in older models or car refrigerators.
- ❄️ R-407C / R-410A - mixtures of various freons, more often used in industrial installations or air conditioning systems, but sometimes found in powerful two-compressor household models.
The transition to new types of refrigerants is dictated by international environmental agreements. Manufacturers are forced to rebuild production, since each type of gas requires specific compressor oil and structural changes to the system. For example, R-600a requires less substance by weight, but requires special protection from sparks.
Table for comparing the characteristics of popular refrigerants
To understand the differences between the substances used in different generations of equipment, let’s consider their main parameters.
| Type refrigerant | Chemical name | Impact on ozone | Safety |
|---|---|---|---|
| R-12 | Dichlorodifluoromethane | High (destroys) | Non-flammable, non-toxic |
| R-134a | 1,1,1,2-tetrafluoroethane | Zero | Non-flammable, safe |
| R-600a | Isobutane | Zero | Explosive |
| R-290 | Propane | Zero | Explosive |
As can be seen from the table, modern environmentally friendly gases are often flammable. This imposes additional requirements on installation and repair equipment. If the label of your refrigerator indicates the content of R-600a, during repairs you cannot use an open flame or a sparking tool in the immediate vicinity of the circuit.
Why can’t you mix different types of freon?
Mixing different refrigerants leads to a chemical reaction, the formation of acids and sediment, which is guaranteed to cause the compressor to fail in a short time.
Symptoms of refrigerant leakage and diagnostics
Since the refrigerant circulates in a closed circuit, its disappearance always indicates mechanical damage. Corrosion of the evaporator (“crying” effect), poor-quality factory soldering or accidental breakdown during defrosting are the main causes of depressurization. Leakage rarely occurs instantly, more often it is a gradual process.
The first signs of a lack of working substance are:
- 🌡️ Weak cooling —food begins to deteriorate faster, the ice in the freezer melts.
- 🔊 Change in operating sound —the compressor may hum differently or turn on more often than usual.
- ❄️ Uneven freezing —in No Frost systems ice may not freeze on the evaporator, or, on the contrary, a “fur coat” forms in one corner.
Diagnostics is carried out using a manometric manifold. The master connects to the process fitting (usually on the compressor) and measures the pressure in the system. For R-134a, the static pressure (refrigerator turned off) at room temperature will be about 4-6 bar, and for R-600a it will be significantly lower, about 2-3 bar. However, an accurate diagnosis is made only after vacuuming and filling using scales.
⚠️ Attention: Self-diagnosis of leaks using soapy water is only possible in accessible areas of the tubes. It is impossible to find internal leaks in the foamed part of the case (where the main evaporator is located) without equipment.
The refilling process and the necessary equipment
Restoring the functionality of the refrigerator is not just “adding gas.” This is a complex technological process that requires adherence to a strict sequence of actions. First, the system is opened, then it is vacuuming to remove air and moisture. Moisture in the system is the main enemy, as it freezes in the capillary, forming an ice plug.
To carry out the work, the master needs:
- 🛠️ Vacuum pump to create a deep vacuum in the circuit.
- ⚖️ Electronic scales for precise dosage of refrigerant (standards are indicated on the tag, deviation ± 5 grams).
- 🔥 Torch and solder for sealing joints (soldering).
- 🧹 Filter drier, which must be changed whenever the system is opened.
The refilling process takes from 1 to 3 hours. First, a new filter drier is sealed, the system is purged with nitrogen, then vacuumed for about 30-40 minutes. Only then is the calculated amount of refrigerant introduced. For R-600a the method of filling in the liquid phase is often used to avoid loss of the composition of the mixture if not a pure substance, but a mixture is used.
☑️ Stages of professional filling
Safety myths and health effects
There are many horror stories around refrigerants. The most common one is that if there is a freon leak, you need to urgently evacuate the apartment. The reality is this: the amount of gas in a household refrigerator is negligible (usually 30-60 grams). Even if the entire volume R-134a or R-600a instantly comes out in a small kitchen, a concentration dangerous for human suffocation will not arise.
However, there are nuances. When freons burn (for example, if a fire breaks out near a leaking refrigerator), toxic decomposition products such as phosgene can be released. Therefore open fire next to a working refrigerator with an isobutane leak is strictly prohibited. Under normal operating conditions, the gases are inert and do not cause poisoning during short-term inhalation of small doses.
Another myth says that “freon needs to be changed every 5 years.” This is absolutely false. If the system is sealed, the refrigerant lasts as long as the refrigerator itself. The need for refueling arises only during repairs or an accident.
Frequently asked questions (FAQ)
Is it possible to fill the refrigerator with freon from a can yourself?
Absolutely not. This requires specialized tools (scales, vacuum degasser, pressure gauges) and knowledge. The wrong amount of gas or the presence of air in the system will instantly kill the compressor.
How can I find out what kind of freon is in my refrigerator?
The information is indicated on a technical sticker, which is usually located inside the chamber (on the side wall or ceiling) or on the back wall of the case. Look for the “Refrigerant” or “R-..” marking.
Why does a new refrigerator make noise when you first turn it on?
This is normal. The refrigerant begins to circulate through the system, gurgling and flowing. The sound of metal expanding may also be heard. After a few hours of operation, the noise usually stabilizes.
Is R-600a (isobutane) dangerous for children and animals?
Inside a closed circuit - no. When there is a leak, the gas evaporates upward (it is lighter than air) and dissipates. The only danger is a spark or an open flame at a time of high concentration of gas in a closed volume.