| Critical pressure. the pressure of saturated vapor at a critical temperature | 5.782 MPa = 57.82 bar |
| Critical density. density in the critical state, when the difference in properties between the liquid and its vapor is lost | 424 kg/m3 |
The most optimal pressure in an air conditioner is considered to be the range of 280-290 kPa. It is not desirable to overfill freon in the system so that to create too high pressure as it will affect the compressor that can either be faster worn out or break down at all.
Let’s normalize the indicators
The control of the air conditioner is very important. As practice shows, the car which has been used more than three years is inevitably in need of freon pumping. It is necessary both for proper functioning of the air handling unit and for more effective and rapid cooling of the air.
It’s not hard to refill the freon by yourself. In addition to the manometric installation, it is worth to have a cylinder with compressed gas, which can be connected to the manometer by means of adapters while ensuring continuous monitoring of the necessary readings.
After connecting a manometer with a cylinder to the air conditioner pipe, you need to start the engine and check the pressure again. Then it is necessary to turn on the cooling device at full power, setting the minimum temperature in the cabin and switching the dampers in recirculation mode.
By unscrewing the tap of the bottle, the required quantity of freon can be pumped. As soon as the pressure gauge gives the expected reading, the tap should be shut off and disconnect the cylinder, then closing the cap on the spigot.
The method is based on the difference between the temperature in the circuit and the boiling point of the refrigerant. To work:
- Switch on the apparatus.
- On the gas pipe install an electronic thermometer. It shows the temperature of the freon in the circuit.
- Use the gauge on the manifold to determine the boiling point of the refrigerant.
- Calculate the difference. Exceeding the limit of 5-8 o C indicates insufficient Freon and the need to refill. Open valve on a bottle, open liquid valve of manifold to bleed air (time. not more than 1 second).
- Open the gas valve of the manifold.
- Measurement of temperature and pressure in the system, calculation of temperature difference.
- Continue the process until the difference is within admissible limits of 5-8o C.
- Close gas valve of manifold.
- Close valve on gas cylinder.
- Disconnect the manifold.
- Close service connection.
How to know how much Freon should be in the split system?
Nowadays there are several types of freon or refrigerant. In the system, this gaseous substance is not only a working element of air conditioning, but also a kind of lubricant for the compressor, which is in any installation.
Steps to Vacuum and Charge Refrigerant on a Mini Split Unit!
Any split unit consists of two units. One is always installed outside the room and the other is always installed inside the room. From one compartment to the other there is a refrigerant pipeline through which freon circulates, as well as electric cable and drainage system. Only tubes of small cross-section in diameter, made of copper, are used for wiring the freon line.
Ways of charging the air conditioner with freon
There are several basic methods of charging of refrigeration systems with freon which are applied to house air conditioners (splits), multi-splits, mobile and multi-zone systems.
Filling the air conditioner with your own hands will require the following set:
- manometer;
- vacuum pump;
- Cylinder with freon;
- construction scales;
- Locksmith tools Swedish wrench, hexes, screwdriver.
Instead of a pressure gauge and a vacuum pump it is possible to buy a manometric station.
Charging by scales
Vacuumizing. Screw a pressure gauge on the shredder and open a tap on it. Turn on the vacuum pump and keep it for 10 minutes. Close the valve on the pressure gauge and turn off the pump.
Connect freon tank. A container with gas is turned upside down and put on the scale, the indicators of which are reset to zero values beforehand. Open the stopcock on the manometer and pour in the required quantity of the refrigerant according to the scales.
Norms for every air conditioner and type of gas that is poured into the compressor are indicated in technical documentation and on its nameplate.
Close the valve and disconnect the pressure gauge, then screw the caps on the ports. Turn on the air conditioner and check its functionality.
This method is considered the most correct, but it is complicated by the need to have expensive scales for weighing freon.
If you want to fill the conditioner 410 with freon by yourself, firstly you have to squeeze all the rest of it in the manometric station for the collection and then to pour the gas by the scales. It is connected with the fact that the given type of freon consists of a mix of various gases with different degree of volatility. If one of the components leaks in a larger volume, the composition changes and consequently the necessary properties of the refrigerant are lost.
If one needs to fill conditioner with freon R22, he/she should use such method as to fill conditioner according to pressure.
Filling by pressure
At first it is necessary to connect the manometer to the gas port of the air conditioner working for cooling. Working pressure of the device should be 3-3,5 atm. If it is lower than these marks, it is necessary to top up. For this purpose, you connect a bottle with freon and start charging it in small portions into the system by opening taps on the pressure gauge for 5-10 seconds.
In order not to burn your hands with gas, it is more convenient to use quick couplings.
This way is convenient exactly when it is necessary to top up the conditioner with the help of your own hands with a small portion of the refrigerant R22. In all other cases, the easiest and best method is to fill with weights, that is by weight.
Charging by superheat and subcooling
In the case of subcooling it is the ratio of the temperature of the liquid to that of the condenser at the same pressure. To determine the temperature of condensation, use a pressure gauge to measure its pressure and then compare the data with the scale values on the pressure gauge manifold, depending on the refrigerant. To determine overheating compare the temperature values of the gas in the normal state and when it is boiling under the same pressure.
Refrigerant leakage and need for topping up is indicated by overheating above and undercooling.
These methods are not suitable for charging home air conditioners, i.e. wall-mounted split-systems. But they are very convenient for semi-industrial units because their outer block has necessary fittings. In addition to these tools one will need an infrared thermometer.
A non-professional can hardly fill up the air conditioner with these two methods, as they require sufficient knowledge in the field of air conditioning systems. Though ease and availability of previous methods for an ordinary man in the street is also questionable.
Conditioner charging according to the current
To determine the operating current of the compressor, you will need special clamp meter, which are put on the phase of the power wire of the operating outdoor unit. If the received values are lower than ones indicated in manual or on a nameplate and the pipe is frozen, it is needed topping up with freon up to evening out the parameters.
All the rest stages fully coincide with the stages of charging air-conditioner with freon according to the scales which you can watch on the video at the end of the article.
This method is also applicable in the case of elimination of the consequences of leakage in semi-industrial equipment.
If the length of freon line of air conditioner exceeds the length of line without refueling indicated by the manufacturer, but not exceeding maximum permissible value, it is necessary to refuel the device on the basis of 30g (up to 3,5 kw) of gas per meter.
Pressure depends on ambient temperature, temperature in a fridge (freezer) and on the parameters of a cooling unit. In steady state mode for single-chamber refrigerators, pressure should be about 0,6 atm, for two-chamber refrigerators 0,2-0,3 atm, for freezers 0,1 atm.
Freon 32 is a refrigerant (or refrigerant) that has no less than twenty names. Technical Characteristics Freon R32.
| Critical pressure saturated vapor pressure at critical temperature | 5.782 MPa = 57.82 bar |
Split System
Let’s speak in detail about the most widespread model of air conditioners. a split-system. It consists of 2 main parts:
- Outside part. Takes in air from the street and recycles it.
- Internal. Supplies purified air to the room and removes contaminated air.
Freon is the main ingredient in the appliance that maintains the temperature of the room. It is located in the connection tubes between the two parts of the device.
Thanks to the convenient separation of the main parts of the device owners have the opportunity to install the air conditioner in any location convenient for them.
The following auxiliary elements are provided in modern models for ease of use:
There are several basic types of the device:
The functionality of each of them provides the operating pressure of the air conditioner. At its deviation from a norm there is a failure in work of all system.
Pressure check
Because of these and some other peculiarities, it is rather difficult to measure the exact pressure of the refrigerant. But this can be done approximately by using a pressure gauge.
The pressure gauge is connected to the valves located on the outdoor unit of the air conditioner. Then the unit is turned on, the “cooling” mode is set. After a short wait (10-15 minutes) you should open the valves and look at the manometer readings. There is no need to measure the pressure in the air conditioning systems with the unit switched off, so you do not get the real picture.
In cases when the charging is performed by a trained employee of a car service center, the surplus of freon will be immediately detected, drained and will not cause any damage to the device. If the surplus of the refrigerant is formed after the “home” charging, there is a great risk that the conditioner will be operated with the excessive pressure in the system.
If the refrigerant R410 is pumped into the main line at the street plus temperature of 24-28 degrees, the pressure will be 6.4 bars, and at the values of 12-15 degrees it will be 5 bars. In case of filling the circuit with R22 freon and the same temperature readings, the pressure will already be 4.3 bar and 3.3 bar, respectively.
