An air conditioner unit may include a housing, an outdoor heat exchanger assembly, an indoor heat exchanger assembly, a compressor, and a sterilization light assembly. The housing may define an indoor portion and an outdoor portion. The housing may further define an exhaust outlet downstream from the indoor portion to exhaust air therefrom. The sterilization light assembly may be disposed within the housing to transmit an ultraviolet light emission thereto. The sterilization light assembly may include a support board, an ultraviolet C (UVC) light source, and a lens casing. The UVC light source may be mounted to the support board and configured to emit radiation between 200 to 280 nanometers. The lens casing may be disposed over the support board and seal the UVC light source to prevent moisture from contacting the UVC light source.