Determination of the exact amount of refrigerant is a critical step in the process of repairing a household refrigeration system technology. Many amateur craftsmen mistakenly believe that they can fill the system “by eye”, focusing only on the temperature of the evaporator or the length of the compressor operating cycle. However lack or excess of freon leads to serious consequences: from failure of an expensive compressor to complete blockage of the capillary tube with ice.
In modern models such as Indesit, Atlant or Beko, a minimum amount of working substance is used, often not exceeding 100 grams. An error of even 10-15 grams can disrupt the thermodynamic cycle. That is why, before starting work, you need to know exactly how many grams of freon are needed for a particular model, and use high-precision scales.
In this article we will look at what the volume of refill depends on, how to calculate the required dose for different types of systems and why the weight indicated on the nameplate is not always the final truth. Understanding these nuances will save you money and nerves when restoring the refrigerator.
Dependence of the filling volume on the type of refrigerant
The amount of refrigerant required directly depends on its chemical composition and physical properties. Different types of freons have different densities and heat capacities, which dictate their own charging rates. Most often found in household refrigerators R134a, R600a and, in older models, R12.
The most common today is R134a (tetrafluoroethane). This is an environmentally friendly gas that replaced freon R12. It requires precise dosing since the system with this refrigerant often operates at higher pressure. An excess of R134a can cause water hammer in the compressor, since the liquid phase does not have time to completely evaporate in the evaporator.
Modern energy-efficient models are increasingly charged with isobutane (R600a). This gas has excellent refrigerating properties, but is flammable. Refilling R600a requires a significantly smaller amount of substance - usually from 30 to 60 grams for the entire circuit. Working with it requires special care and evacuation of the system to very low values.
⚠️ Attention: Never mix different types of refrigerants! If the system had R12, you can’t just fill it with R134a without completely flushing and changing the oil. This will lead to the formation of an acidic environment and destruction of the compressor windings.
The exact type of refrigerant used is always indicated on the factory sticker located inside the refrigerator compartment or on the rear wall of the unit. Ignoring this information and refilling “with what is in the cylinder” is a grave mistake.
Where to find the exact dosage for your model
The first and most reliable source of information is the technical label (nameplate) of the refrigerator itself. The manufacturer is required to indicate the type of refrigerant and its mass in grams. Typically, this sticker is located inside the refrigerator compartment on the side wall or on the rear panel of the case.
However, if the sticker is worn off or missing, you can use reference tables compiled based on the technical data sheets of popular models. Below is a table with approximate data for common brands.
| Refrigerator brand | Refrigerant type | Approximate weight (grams) | System type |
|---|---|---|---|
| Atlant (single-compressor) | R134a | 110 - 130 g | No Frost / Crying |
| Indesit (European assembly) | R600a | 45 - 65 g | Static |
| LG (double-circuit) | R134a | 180 - 220 g | No Frost |
| Beko (compact) | R600a | 35 - 50 g | Static |
| Stinol (old models) | R12 | 140 - 160 g | Crying |
It is important to understand that the values in the table are averaged. Actual weight may vary depending on year of manufacture and chamber size. If you are changing a compressor, the new unit may already contain oil, but not contain freon, so refueling is done strictly by weight.
What to do if the sticker is not readable?
If the manufacturer's label is damaged, you can try to find the technical data sheet of the model by serial number on the manufacturer's website. As a last resort, experienced craftsmen calculate the volume empirically, starting with a minimum dose and adding 5-10 grams, controlling currents and temperatures, but this requires high professionalism.
Calculating the amount of freon when replacing a circuit
The situation changes dramatically if you replace the evaporator ("crying" panel) or everything foamed contour. In this case, the factory sticker becomes irrelevant, since the length of the tubes and the volume of the system may have changed. Standard practice is to add a certain amount of refrigerant for each linear meter of a new tube.
For systems operating on R134a, it is customary to add approximately 10-12 grams of freon for each meter of evaporator tube length. If you install a standard aluminum evaporator, which often comes with a tube about 6-8 meters long, the calculation will be based on this length. However, if you use a copper coil, its length may be different.
- 📏 Measure the exact length of the installed evaporator from inlet to outlet.
- ⚖️ Weigh the empty freon cylinder before starting refilling to control consumption.
- 🧊 Take into account the volume of the receiver (filter-drier) if it is non-standard.
When using isobutane (R600a), the calculation is different. Since very little is required, craftsmen often focus not only on the length, but also on the suction pressure. The typical norm is about 6-8 grams per meter of tube, but the final dose rarely exceeds 60 grams even for large refrigerators.
Methods for controlling the amount of gas filled
Just knowing how many grams you need is not enough. It is necessary to be able to control the process of filling the system. There are several methods, each of which has its own advantages and limitations. The most accurate and professional is considered refilling using scales.
With the weighing method, the freon cylinder is placed on an electronic scale. After the system has been evacuated, the valve opens and gas enters the circuit. The master monitors the scale readings in real time. As soon as the arrow shows that the required amount has been selected (for example, minus 115 grams from the initial weight), the feed stops. This is the only method that guarantees accuracy down to the gram.
The second method is control by current consumption compressor. It is used as an auxiliary. The nameplate indicates the rated current (for example, 0.8 A). If freon is underfilled, the current will be lower than the nominal value, and if it is overfilled, it will be higher. However, this method is not accurate, since the current depends on the network voltage, ambient temperature and compressor wear.
⚠️ Attention: Controlling refilling only by the pressure in the system (pressure gauge) is a gross mistake! The pressure in the system depends on the ambient temperature. In summer at +30°C the pressure will be high even with underfilling, and in winter at +15°C it will be low even with overfilling.
The third method used in field conditions without scales is temperature control. The technician touches the condenser (the grille at the back) and the evaporator inside with his hand. When charged correctly, the capacitor should be hot (50-60°C) for 2/3 of its length, and then cool down. The evaporator should be evenly covered with frost. If only the beginning of the tube freezes, there is not enough freon. If frost reaches the outlet of the evaporator and goes to the compressor, there is a lot of freon.
Consequences of violating the refrigerant dosage
Why is it so important to follow the grams? Let's look at the physics of the process. When lack of freon (underfilling), the compressor runs idle, trying to gain temperature. The suction pressure drops, which leads to overheating of the motor. The oil in the compressor stops returning normally from the system, which causes oil starvation of the bearings and jamming.
In addition, if the refrigerator is underfilled, it does not reach the required temperature. The compressor runs continuously, without shutdown cycles. This leads to rapid wear and burning of the windings. In systems with No Frost there may be insufficient defrosting of the evaporator, which leads to the formation of an ice coat and stopping air circulation.
When excess freon (overflow) the situation is no less dangerous. Liquid freon does not have time to evaporate in the evaporator and enters the suction pipe of the compressor in the form of drops or liquid. Occurs hydraulic hammerwhich can instantly destroy the compressor valves or break the connecting rod. The condensation pressure also increases sharply, the compressor is overloaded, and the refrigerator freezes too much, turning food into ice.
☑️ Checking the correct filling
Common mistakes when refilling yourself
Independent repair of refrigerators is full of risks. One of the main mistakes is ignoring the stage vacuum. Before starting new freon, air and moisture vapor must be removed from the system. If this is not done, the moisture in the system will freeze in the capillary tube, forming an ice plug. The refrigerator will stop freezing after a few hours of operation.
The second mistake is using the wrong oil. Each type of freon requires a compatible oil. For R134a you need synthetic polyester oil (POE), which is hygroscopic (absorbs moisture). For R600a i R12 —mineral. Mixing oils or using mineral oil with R134a will lead to stratification of the mixture and failure of the lubrication system.
The third mistake is saving on the filter drier. This element is inexpensive, but its role is critical. It collects moisture and oil breakdown products. Every time the system depressurizes (and refueling without this is impossible), the filter