Fresh air generally means that the hanging machine is equipped with a filter screen, which can filter out some dust. Some air conditioners are equipped with a sterilization filter screen, which can also play a certain sterilization role, in addition to the four pests (benzene, formaldehyde, germs and odor). , can play the role of fresh air. The principle of air conditioning refrigeration is to change the indoor temperature by absorbing and releasing heat through the state change of refrigerant, not to say changing air. Therefore, if there is no more advanced air conditioning now, even if there is air conditioning, the room can't be closed all the time, so the air can't circulate.

The structure of air conditioning generally consists of the following four parts.

Refrigeration system: it is the refrigeration and cooling part of air conditioner, which consists of refrigeration compressor, condenser, capillary tube, evaporator, electromagnetic reversing valve, filter and refrigerant to form a sealed refrigeration cycle.

Air duct system: it is the part of air conditioning to accelerate indoor air heat exchange, and it is composed of centrifugal fans, axial fans and other equipment.

Electrical system: it is the part of air conditioning that ensures the safe operation and temperature control of compressor and fan, and consists of motor, thermostat, relay, capacitor and heater.

Box and panel: it is the frame of air conditioner, the supporting seat of each component and the guiding part of air flow, which consists of box, panel and louver.

Evaporator and condenser are actually only relative. When refrigerating, the evaporator is an internal machine and the condenser is an external machine. When heated, it's the other way around.