A packaged terminal air conditioner unit (PTAC) includes a vent aperture defined in a bulkhead of the PTAC and a fan assembly for urging a flow of make-up air through the vent aperture. The fan assembly includes a fan duct fluidly coupled to the bulkhead over the vent aperture and an auxiliary fan attached to the fan duct. An electronics assembly includes an electronics enclosure mounted to the fan duct and defining an electronics compartment having an opening for receiving power electronics for controlling the auxiliary fan. A top plate is attachable over the opening and a seal is positioned between the top plate and the electronics enclosure to substantially enclose and seal the electronics compartment.