The principle of operation of air conditioning systems always boils down to the same:
absorb the energy of one place and release it in another.
This process requires an internal unit (which has the evaporator), an external unit (which has the condenser) and copper tubes to connect the two units. Through these tubes, the refrigerant flows from one unit to another. It is the refrigerant that absorbs the energy of one unit and releases it in the other.
