What is the working principle used in an air conditioner to cool your room temperature? I got few more information at pickeronline.com but not understand?

An air conditioner collects hot air from a given space, processes it within itself with the help of a refrigerant and a bunch of coils and then releases cool air into the same space where the hot air had originally been collected. This is essentially how all  air conditioners work.

Many folks believe that an air conditioner produces chilled air with the help of machines installed inside it, allowing it to cool a room so quickly. That might also explain why it consumes so much electricity. In reality, however, that’s a misconception. An air conditioner is not a magical device; it just uses some physical and chemical phenomena very effectively to cool a given space.

When you switch an AC on and set your desired temperature (say, 20 degrees Celsius), the thermostat installed in it senses that there is a difference in the temperature of the room’s air and the temperature that you’ve chosen.

This warm air is drawn in through a grille at the base of the indoor unit, which then flows over some pipes through which the refrigerant (i.e., a coolant fluid) is flowing. The refrigerant liquid absorbs the heat and becomes a hot gas itself. This is how heat is removed from the air that falls on the evaporator coils. Note that the evaporator coil not only absorbs heat, but also wrings out moisture from the incoming air, which helps to dehumidify the room.

This hot refrigerant gas is then passed on to the compressor (located on the outside unit). Being true to its name, the compressor compresses the gas so that it becomes hot, since compressing a gas increases its temperature.

This hot, high-pressure gas then travels to the third component – the condenser. Again, the condenser remains true to its name, and condenses the hot gas so that it becomes a liquid.

The refrigerant reaches the condenser as a hot gas, but quickly becomes a cooler liquid because the heat of the ‘hot gas’ is dissipated to the surroundings through metal fins. So, as the refrigerant leaves the condenser, it loses its heat and becomes a cooler liquid. This flows through an expansion valve – a tiny hole in the system’s copper tubing – which controls the flow of cool liquid refrigerant into the evaporator, so the refrigerant arrives at the point where its journey started.