How does air conditioner work?

Air Conditioner works on the principle of a closed cycle. The air in the room is cooled by passing through the heat exchanger of the indoor unit, in which the refrigerant evaporates. Let’s see how air conditioner works in this step by step guide.

How does air conditioner work

The compressor, installed in the outdoor unit, compresses the refrigerant and forces it in a gaseous state from the evaporator of the indoor unit to the condenser.

In the condenser, the freon is cooled by heat exchange with the outside air and condenses. All this takes place in the heat exchanger of the outdoor unit. 

The refrigerant then passes through the throttling device, where the freon pressure and temperature decrease sharply. In this case, part of the liquid refrigerant inevitably transforms into a gaseous state.

The cold freon enters the heat exchanger of the indoor unit (evaporator), where due to the heat exchange with the air from the room, it boils and turns from the liquid state into gaseous one. The air, in its turn, cools down and enters the room. 

Due to peculiarities of air conditioner functioning, drops of water – condensate are formed on the evaporator. Usually during installation of the system, a separate pipe is installed for condensate drainage. It goes out into the street or into the sewer, so that there is no excess moisture in the room. 

The direction of outgoing air from the indoor unit is regulated horizontally and vertically by a special curtain and louvers.

How reverse cycle air conditioner works

How reverse cycle air conditioner works

The peculiarity of reverse cycle air conditioner is that the compressor switches on once during all work of the conditioner and stays in this state permanently, changing the number of rotations depending on the load on the conditioner. While a usual air conditioner (on/off) switches on and off periodically, without changing the number of turns. Inverter saves energy and prolongs life of the compressor, because it does not switch on/off, but smoothly changes the number of revolutions. 

An inverter model will be more economical than any other air conditioner if it runs for at least several hours without shutting down.  

An inverter model, like a conventional air conditioner, has two units – an outdoor unit and an indoor unit. The outdoor one has a compressor, copper freon piping, a fan and a condenser. The internal block consists of evaporator, fan, louvers, filter and special tray for the formed condensate.

How split-system works

Normal classical split-system consists of two modules (blocks) – external and internal. The structure of the external unit of split-system of on/off type is almost always the same.

Outdoor unit

The external unit includes the compressor, condenser, four-way valve, it also has a capillary tube. In all units there is a filter-drier, which cleans and dries the refrigerant from the possible ingress of moisture into the system and various kinds of impurities. In split-systems of inverter type in the outer block there is also a control board, which is present in multi split-systems. Due to the fact that the compressor is situated exactly in the outside block, the noise level of the running conditioner in the apartment is much lower than in the streets.

The size of the outer unit may differ depending on the model performance, as well as on the brand.

The connection of the indoor unit with the outdoor unit is made with the help of freon piping. There is also a drainage line, and an electrical cable to power the indoor and outdoor unit.

The outside unit of the air conditioner must always be located on the street side. It is mounted on the outside of the wall. If it is necessary to install a conditioner at a sufficient height from the ground and it is not possible to install an external unit in a usual way, we invite mountain climbers with special equipment. Without such equipment it is impossible to install the outdoor unit high up.

Also, the outdoor unit can be installed on the roof of buildings, on unglazed balconies and loggias, open common balconies or stairwells with open access to the street.

Often, outdoor units are supplied in an anti-vandal enclosure, if this is not provided by the manufacturer, the unit installed at first floor level may additionally be placed in a special protective box of metal bars. To avoid the accumulation of snow or rain water, as well as debris, sometimes a special beveled canopy is installed over the outdoor units.

Indoor Unit

Inner blocks of split-systems differ from each other considerably. Firstly, it depends on the producer, that is all the inner blocks differ in their design, secondly, the blocks differ in the type of installation, and consequently have a considerable difference not only in the design of the front, but in the body as a whole. Also, the indoor units, depending on the manufacturer, power and model, can differ in accessories, functionality, overall dimensions.

Inner blocks of split-systems can be of the following types:

  • wall-mounted – they are designed to be installed on the wall;
  • cassette – they are located in the area of under-ceiling space;
  • channelized – they are installed in the area of ceiling space with air ducts system;
  • floor-ceiling – can be installed both on the floor and in the area under the ceiling
  • columns, installed on the floor, have bigger sizes in comparison with other types of classical split-systems’ indoor blocks.

The work of the internal block is regulated with the help of electronic board. In the internal block there are filters for air cleaning, automatics, evaporator and fan for blowing the exchanger of the evaporator.

The main functions of modern split-systems – ventilation, dehumidification, cooling, heating and maintaining the set temperature in the room.

Controlling by remote control. Almost all modern models of split-systems are equipped with a remote control. Controlling all the functions, i.e. setting temperature mode, timer switching, programming of tasks, switching all the modes, provided by a definite air conditioner model, is fulfilled not only by switching on and off of the device with its help.

If the function “I feel” is realized in the model, then due to the temperature sensor in the remote control the conditioner monitors the ambient air temperature in the room, and when the temperature set by the user is reached, the equipment maintains it.

On the indoor unit, the direction of air flow is adjusted by changing the angle of the louvers.

The operation of the compressor of the outdoor unit is regulated by the constant control of all systems.

How floor air conditioners work

These models are rarely used if it is not possible to install a standard split. Floor air conditioners also can be only stationary. Stationary models have the same principle of work, as a usual air conditioner, except the inner block is installed. It is placed not under the ceiling, but at the height of half-meter from the floor. Outer block is situated in the street. Such split-systems are referred to as semi-industrial series. As a rule, they are characterized by higher productivity than domestic models.

Portable air conditioners

Mobile model has only one unit, located indoors. It contains a compressor, evaporator and condenser. The mechanism of functioning is based on the processing of air that is inside the room.

Usually it is not recommended to choose a mobile model, because the noisiest part will not be installed outside the window, but in the room. When the air conditioner is on, you will be uncomfortable in the room. In addition, they are characterized by low power.

What is the difference between air conditioner and split-system

Conditioner is a complex technical equipment that is aimed for creation and keeping a comfortable temperature in the room for any purpose. An air conditioner can not only cool the air, but also heat it, if it is foreseen by the manufacturer.  Air conditioner is a general term of climate-controlled refrigeration equipment. Nowadays there are many kinds of air conditioners. Conditioner can be called a domestic device for cooling air, such as a window air conditioner or mobile air conditioner, as well as a chiller – industrial climate equipment of high capacity. For more precise definition there are names of air-conditioners, for example, split-system.

Split-system is an air conditioner, which consists of two blocks – outside and inside. Inner block includes a control system – automatics, filters for air cleaning, fan for blowing evaporator coil and evaporator itself. The external unit includes compressor, condenser, four-way valve, capillary tube and automation system.

Domestic split-system is most often installed in relatively small rooms, for example, a domestic wall-mounted split-system is designed for creating the optimal microclimate in the rooms of 10 to 70 m2, depending on the capacity of the equipment. That is why such split-systems are more often installed in apartments or in small office rooms.

One indoor unit is able to maintain the temperature in one room, if the maintenance of the temperature in several rooms at the same time is required, then there are multi split-systems for this purpose. Such a system supposes connection of several inner blocks to one outer.

There are also other types of split-systems, which are more suitable for spacious premises with big areas – shopping centers, restaurants, business centers, etc. All these split-systems also have one internal and one external unit, they differ only in internal units and productivity. Inner units are divided according to the type of installation – cassette, canal, column, floor-ceiling and column units.

Split-systems can differ in options and functions, this depends on a model and a manufacturer. For example, in split-systems there can be different quantities of air filters. The number of modes may also differ – some air conditioners have the following popular modes – “I feel”, night mode, self-cleaning, auto restart, auto shutdown, self-diagnosis, turbo mode, smart defrost, etc.

How to choose a split-system for a house

Choosing an air conditioner for a house, take into consideration the size of a room. For a small room (up to 15-20 meters) the system with 7000 BTU will be enough. For a room up to 25 square meters it is better to choose a more powerful model – 9000 BTU. 

Think about the electricity costs and choose energy-saving model A++, the consumption of about 700-800 watts. If the budget allows you to buy conditioner A+++ with consumption of 500-600 watt. 

Estimate the level of noise. If possible, listen to how the system is working, because you will have to be in the room during the conditioner’s work. Allowed value of noise for an inner block is 19-32 dB.

Advantages and disadvantages of air conditioners 

If you are going to buy an air conditioner or a split system, you will be interested to know about the pros and cons.


Providing a comfortable temperature in the room. Regardless of the weather outside, a split system will create a favorable atmosphere in the room. In summer the air conditioner will cool the air, and in Autumn or Spring it will heat it. In any case it will be comfortable in the room. 

Clean indoor air. This is especially important for residents of large cities living in industrial areas. Using an air conditioner will allow you to get cool, clean air without opening windows.

Maintaining optimal air humidity. Some models have a dehumidification function, creating an optimal level of humidity in the room. 


Note that an air conditioner can only cause harm to humans if used improperly. If the unit is not cleaned regularly, harmful bacteria and viruses can begin to breed in it. 

Due to the nature of the air conditioner, the air in the room becomes drier, so we recommend using separate devices that increase the level of humidity in the room. 

During operation, compressors make a little noise. Usually the compressor is in the outdoor unit and you can’t hear it running in the room.  

Maintenance and repair

The air conditioner should be cleaned regularly and preventive maintenance should be done to ensure that all systems are working properly. You can clean the filter yourself, knowing the structure of the model, or you can call a specialist, who will do it in 30-60 minutes. 

If the air conditioner is broken, do not repair it yourself, call the service department and describe the problem. Sometimes breakdowns are solved within a few hours on the spot. For example, if the split-system turned off because of overheating after prolonged work, the cause is most likely in the compressor overheating or in the radiator contamination. The problem is solved by cleaning the grill.

If the unit is not running at full capacity, check the air filters. They may need to be cleaned.