It is a small, lightweight unit made out of aluminium and built into a rigid steel frame. The unit is designed to be placed outside, with supply air and return air ducted to the tent. For field hospitals where a higher filtration than for normal accommodation is wanted, a dual filtration system for the internal air path is available.

The function of the ACM 18 is based on a cooling circuit and two powerful fans. The evaporator section contains the evaporator and a radial fan, which draws warm internal air of the tent through the cold evaporator and blows out the cooled air through the side or the top of the unit. The condenser section contains two condenser coils and a large axial fan, returning the heat taken from the internal air to the outside atmosphere.

The ACM 18 can be equipped with an electric heating coil, to provide heating for example for night time when temperatures can fall under 20°C.

All sheet metal parts are protected against corrosion by a minimum 80μm top coat.