The proper operation of climate engineering directly depends on the integrity of the refrigeration circuit, and the slightest depressurization can negate the effectiveness of expensive equipment. The loss of refrigerant leads not only to a decrease in cooling capacity, but also to the risk of overheating of the compressor, which entails complex and costly repairs. That is why the question of how to check the tightness of split systems is paramount in installation or diagnostics of malfunctions.
In the professional environment, this process is called pressing, and it is a set of actions to create excessive pressure in the highways to identify leakage sites. Leakage of the contour This is a fundamental requirement, without which it is impossible to guarantee a long service life of the air conditioner. Unlike household appliances, inert gases and precise gauge stations are used here, allowing you to track even microscopic changes.
In this article, we will discuss in detail the diagnostic technologies, the necessary tools and criteria for determining the suitability of the system for further operation. You will learn why simple soap solution is not always effective and how professionals find defects that are invisible to the eye in hard-to-reach areas of the track.
Causes of depressurization of the refrigeration circuit
Violation of the integrity of the freon pipeline most often occurs at the stage of poor-quality installation, when critical errors are made when rolling the connections. A poorly rolled tube or a pulled nut creates a stress in the metal, which over time leads to the formation of microcracks under the influence of vibration. The junctions of copper and brass are the most vulnerable points that require special attention during the initial inspection.
In addition to installation defects, the cause of leaks can be external mechanical damage caused during the laying of the track or during facade work. Corrosion also plays a role, especially in coastal areas where salt air aggressively affects copper tubes and heat exchangers. Freon leak It can also be caused by factory defects, for example, poor-quality soldering of the evaporator or condenser, which manifests itself in the first months of operation.
- 🔧 Vibrational destruction: constant vibration of the compressor shakes poorly fixed structural elements.
- 🌡️ Thermal expansions: heating and cooling cycles cause the metal to expand and contract, weakening the compounds.
- 🏗️ Mechanical effectsimpact, pressure of snow or falling objects on an external block.
⚠️ Even a microscopic crack with a diameter of several microns can completely empty the circuit in one season, so visual inspection is often insufficient.
Understanding the nature of defects helps you choose the right search strategy. If the system is new, most likely, the problem is installation, whereas in old air conditioners it is worth looking for traces of corrosion or fatigue of the metal. Copper tubes. They have high plasticity, but with frequent temperature changes lose their properties and become fragile.
Required diagnostic tools
To conduct a qualitative test of tightness is not enough to have only wrenches and the desire to understand the problem. The professional set of the master includes specialized equipment that allows you to work with high pressures and inert gases. The fundamental instrument is gauge-stationThis allows you to control the pressure in the circuit with high accuracy.
The second critical element is a dry nitrogen cylinder equipped with a gearbox. Nitrogen is not chosen by chance: it is an inert gas that does not react with oil and system components, and also does not contain moisture that can freeze and clog the capillary tube. The use of oxygen or compressed air from the compressor is strictly prohibited, as it can lead to an explosive situation or oxidation of internal surfaces.
Additionally, leak detectors are used to search for leak sites, which can be electronic or work with ultraviolet tags. Electronic flow detectors They are able to respond to the minimum concentrations of refrigerant in the air by sounding. Also in the arsenal should be high-quality valves, adapters and, of course, personal protective equipment, as working with gas under pressure requires caution.
Preparation of the system for nitrogen pressing
Before applying pressure, it is necessary to carefully prepare the contour, removing from it the remnants of old freon and, more importantly, moisture. If the system is new, this step is reduced to checking the integrity of the package and the absence of plugs at the ends of the pipes. In the case of repairs or maintenance, the first step is always to vacuuming A system that allows air to be pumped out and water contained in highways to be evaporated.
The preparation process involves connecting the gauge station to the service ports of the external unit. It is important to make sure that the valves on the unit itself are closed so as not to damage the internal components with high nitrogen pressure. Pressure is supplied through a separate fitting, and the filling rate must be controlled to avoid sudden jumps that can damage weak spots.
☑️ Checklist for preparation for pressing
Control of ambient temperature is critical, since the gas pressure directly depends on this parameter. A 1 degree Celsius change in nitrogen temperature causes a pressure change of about 0.05 bar.This is something that needs to be taken into account during long-term measurements. If you ignore this physical law, you can falsely diagnose a leak where there is none, or miss the real problem.
Technology of pressure testing and norms
The process of compression is to pump nitrogen into the circuit to a certain level, which depends on the type of refrigerant used and the recommendations of the equipment manufacturer. For most household systems that operate on R410AThe operating pressure is much higher than that of the systems on R22The test pressure should be appropriate. Usually the circuit is filled up to 25-30 bar, but the exact figures should always be viewed in the technical documentation.
After reaching the required pressure level, the system is cut off from the cylinder and left for a certain time, usually from 30 minutes to 24 hours. During this period, the pressure gauge readings shall not be changed unless temperature compensation is taken into account. Any drop in the manometer arrow, not associated with a change in air temperature, indicates the presence of leakiness in the system.
| Type of refrigerant | Working pressure (approximate) | Nitrogen test pressure | Cover time. |
|---|---|---|---|
| R22 | 16 bar | 20-25 bar | minimum 1 hour |
| R410A | 28 bar | 35-40 bar | minimum 1 hour |
| R32 | 26 bar | 35-40 bar | minimum 1 hour |
| R134a | 7 bar | 15-20 bar | minimum 1 hour |
A sharp increase in pressure can damage the sensitive elements of the pressure gauges or the system itself, if there are hidden defects in it. Pressure control It should be constantly in the initial phase to record the moment of stabilization.
Why can’t you use oxygen for scaling?
The use of oxygen or compressed air with an oxygen content is unacceptable, since when mixed with compressor oil, an explosive mixture is formed. Even a spark of static electricity can detonate inside copper tubes, tearing them apart and damaging property. Nitrogen is an inert gas and is completely safe in this regard.
Methods of finding refrigerant leakage sites
If the pressure gauge showed a drop in pressure, the stage of localization of the defect occurs. The simplest, but not always effective method is the use of soap solution. The concentrated solution is applied to all threaded joints, rollers and soldered seams. The appearance of inflatable bubbles clearly indicates the location of the gas release, but this method is useless for searching for leaks in hard-to-reach places or inside heat exchangers.
A more advanced way is to use ultrasonic leak detectorsThey're the ones that pick up the sound of gas coming out. This method is good because it allows you to scan the track from a distance and find places that are physically difficult to reach. However, in noisy environments or in high winds, the effectiveness of the ultrasound method can be reduced, requiring the use of headphones and careful sensitivity adjustment.
- 🫧 Soap solutionThe classic method for visible compounds requires direct access.
- 📡 Electronic flow detectorReacts to Freon vapors, is effective for hidden places.
- 💧 Immersion in water: applicable only to individual dismantled nodes (radiators).
For complex cases where leakage cannot be found by standard methods, the method of increasing the pressure to the maximum permissible values (with caution) or the use of a gas mixture with a dye is used. Search for leakage It is a process that requires patience, as gas can escape through microscopic holes very slowly.
⚠️ Note: When using an electronic leak detector, move the probe slowly, no faster than 2-3 cm per second, otherwise the device may not have time to react to the concentration of gas.
Vacuuming as the final stage of the inspection
After successful pressing and elimination of all found defects, the system must be evacuated. This process serves a two-fold purpose: removing nitrogen residues and, most importantly, removing moisture that could have entered the circuit during work. Vacuuming is also an indirect test for leakage: if after turning off the vacuum pump, the pressure in the system does not increase for a long time, then the system is sealed.
For this operation, a two-stage vacuum pump is used, capable of creating a deep vacuum. The process can take anywhere from 30 minutes to several hours depending on the length of the track and the pump power. It is important to use a manovacuummeter to control the depth of the vacuum, since it is impossible to determine the end of the process by hearing.
Use an electronic scale when filling with Freon after vacuuming is the only way to guarantee an accurate amount of refrigerant, as filling "by eye" or pressure often leads to errors.
The mistake of many beginners is the neglect of the vacuum time, believing that it is enough just to "suck" a couple of minutes. In reality, the moisture in the system in the form of steam begins to actively evaporate only in a deep vacuum, and this process takes time. Residual moisture In the system, it is a guarantee of the formation of acids and blockage of the system with an ice plug in the future.
Vacuuming is not just the removal of air, it is a mandatory procedure for removing moisture, without which the long-term operation of a split system is impossible.
Frequent errors in the diagnosis of tightness
One of the most common mistakes is to ignore the temperature coefficient. Masters often record a drop in pressure in the evening when the temperature has dropped, and conclude that the leak, although the system is completely sealed. It is necessary to record the readings of the pressure gauge and ambient temperature in order to recalculate or simply wait for the temperature to stabilize.
Another mistake is the use of poor quality consumables. Cheap hoses for pressure gauges can pass gas themselves or have microcracks, which confuses the diagnosis. Always check the integrity of your tool before you start. Quality of diagnosis It depends on the serviceability of the master’s equipment.
There is also a lot of haste when it comes to work. The 15-minute pressurization does not guarantee that the system will not lose Freon in a month. Professional approach requires exposure of the system under pressure for at least several hours, and ideally - leaving it under control for a day.
Can I check the tightness of a split system without nitrogen?
In theory, dry air or the refrigerant itself can be used under low pressure, but this is less efficient and potentially dangerous. Nitrogen is preferred because of its inertia and lack of moisture. Testing with working gas requires a large amount of it to create the necessary pressure, which is economically impractical and environmentally harmful with possible embellishment.
What is considered a normal drop in blood pressure when tested?
In a perfectly sealed system with temperature compensation, the pressure drop should be zero. Minimum fluctuations within the gauge error (0.1 to 0.2 bar) are allowed if they correspond to changes in ambient temperature. Any drop that exceeds the temperature correction indicates a defect.
Is nitrogen dangerous to humans when tested?
Nitrogen is not toxic in itself and makes up most of the atmosphere, but it is under high pressure in cylinders. The danger is a rupture of the hose or improper handling of the gearbox, which can lead to injury. Also in enclosed spaces, the displacement of a large volume of nitrogen can reduce the concentration of oxygen, so ventilation is important.
Should I vacuum the system if it was just spun for 5 minutes?
Yes, I will. Even in 5 minutes, humid air enters the system. Moisture in the refrigeration circuit is the main enemy leading to the formation of ice stoppers in the TRP and corrosion. Neglecting vacuuming after any depressurization of the circuit reduces the life of the air conditioner.