A window-type air conditioner housing includes a backboard and two parietal sideboards of polystyrene. Each sideboard has a steel plate implant and a coaxial bracing hole for supporting a motor and an associated air conditioner fan bearing components, respectively, to thereby maintain vibration and noise at reduced levels. Preferably each steel plate implant is dimpled in the area surrounding each coaxial bracing hole to strengthen and stiffen the sideboard in that area for supporting the motor and fan assembly.