This paper investigates the overheating due to overabundant solar gains through fully glazed facades, aligned on the heliothermal axis. An Italian sick building was selected as case study to quantify the level and the characteristics of discomfort and verify whether a smart control of the AC system could suffice in restoring satisfactory environmental conditions. Fuzzy control logics were designed and implemented to regulate the speeds of the false-ceiling fan coil unit serving the office, selected as exemplary environment. Data were collected by an articulated sensor network mapping internal and external climate conditions as well as the thermal distribution on the internal side of the glazed facade and inside the fan coil ducts. Each configuration was assessed on a representative sunny day in terms of global comfort (operative temperature, PMV), local discomfort (draught rate, vertical gradient) and energy consumption. Serious overheating episodes were recorded throughout the year and in every configuration. Nevertheless, non-negligible improvements were achieved by including outdoor temperature and solar radiation in the control algorithm which allowed to narrow down the offset from to the set point (resulting in PMV < 1 for the 97.2% of the time) and limit the use of the full-power mode (with all associated energy benefits).