No person shall park any commercial vehicle, having an unladen weight exceeding five thousand (5,000) pounds in any residential district except: (a) while loading or unloading property; or (b) when such vehicle is parked in connection with, or in aid of, the performance of a service to or on a property in the block in which such vehicle is parked. A “residence district” shall be determined as per California Vehicle Code, Division 1, Section 240 or Section 515, or as those districts or areas zoned as residential and indicated as such on the city zoning map, including low-medium, and high-density residential. (Prior code § 3010(i))