How air conditioner modes work: cooling, heating, dehumidifying


  • Author Stan Clarck
  • Published July 2, 2021
  • Word count 851

Air conditioner is a definition for an air conditioning system that we don't always get right. The word "air conditioner" is usually associated with the African summer heat and a rattling box in the window. Or laundry detergent. But a room air conditioner is more than just a "cooler," it's a means of airing and restoring the air. The climatic system is able to heat, dry, humidify, filter and even ionize the air - and all in one bottle.


Air cooling in a split system is done through a phase transition. We are going to omit complicated technical details in order to understand everything from the first time, and we will explain it on our fingers. And literally.

Heat water up to 37-38 °С, wet a rag and hold it on the back side of your hand - is it warm? Now blow on the spot - is it cool? Wipe it dry and compare the temperature of one hand to the other. Water, even heated above body temperature, has cooled your skin, and this is not magic, but a law of nature. As water evaporates into the atmosphere, it takes some of the heat radiation from the surface with it. This is how the normal human cooling system works - by overheating, the body gets rid of the surface heating along with the evaporating sweat.

The air conditioner operates a similar system, only instead of sweat an inert gas is used, and heat is taken from the room air. To start this process, a compressor compresses freon in a closed system to 20-25 atmospheres, thereby heating it to 80-90 °C. The compressed gas is then fed to the external evaporator (outdoor unit), cooled and transferred to part of the indoor unit. Then the heavily compressed gas meets an obstacle in the form of a capillary choke - a copper tube with a very small diameter, as it passes through which the freon turns into gas again and begins to actively remove heat from the internal heat exchanger. As a result, the radiator quickly draws heat from the room air and transfers it to the freon. This process is repeated until the air conditioner cools the room air to the set temperature.


Dehumidification exists by default in all modern split systems and works practically the same way as "snowflake". However, the effect obtained from the system's nozzles is slightly different.

In the standard cooling mode, the air conditioner mixes the room air within the indoor unit. As a result of the warm air hitting the cooled radiator fins, condensation, a concentration of moisture from the air, occurs. You can get this effect by breathing on the glass - first it will fog up and then the moisture will form into droplets. The strength of the effect depends on the difference in temperature, humidity level and atmospheric pressure. The more moisture in the air and the higher its temperature, the more condensation will remain on the icy radiator and then enter the street through the drain.

To avoid overcooling the air, but to get rid of dampness, you have to use dehumidification mode. The principle of work is identical to the standard work of air conditioner at minimum temperature, but instead of stirring up air with high speed, the conditioner reduces the revolutions of the fan and works at ground level. In this mode, the radiator doesn't have time to quickly give up the cold to the passing stream, but it effectively condenses moisture. This is how the basic "dryer" works.

Nevertheless the air is cooled and we cannot call it full-fledged dehumidification. Let's imagine the following situation: it is summer, it is +28 °C outside, and it has just rained heavily. It is hot, stuffy and humidity is just over-scale. We switch on air conditioner in drying mode and go ahead - it dries and refreshes at the same time. But what if it is autumn, high humidity, and ambient temperature is not "under thirty" already, but only +10-15 °C? You want not only to get rid of moisture in the room, but also to keep warmth. For this purpose modern systems use a hybrid radiator and a special valve which regulates freon pressure in the condenser of the indoor unit and divides it into two parts. One half of the radiator continues to cool and dehumidify the air, while the other half heats to maintain temperature balance.

Fan and filtering

In this mode, the split system ceases to be an air conditioner and becomes an ordinary fan. Only a couple of commands are left at user's disposal with remote control - blow faster and direct the stream to the ceiling. And still such system is different from the classical floor fan.

The air in your room can be compared with a layer cake - it is hot on top, warm in the middle and cold at the bottom. And, if in winter the room is heated and the radiators contribute to mixing, then in the off-season this process is suspended. Then in a bright room with several windows it become

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