What is the definition of a wall split unit? A wall split unit is a type of air conditioning unit typically used in homes and commercial buildings. It consists of two main parts, an indoor unit and an outdoor unit. The indoor unit, which is installed in the wall, is connected to the outdoor unit, which is placed outside of the wall. The indoor unit contains an evaporator coil, a condenser coil, and a compressor. The outdoor unit houses the condenser coil and the compressor. The unit works by drawing air from the room and passing it over the evaporator coil, which cools the air and releases it into the room. At the same time, the outdoor unit draws in the warm air from the outside and passes it over the condenser coil, which cools it and releases it back outside. Through this process, the wall split unit is able to effectively cool down the room.