you have more problems than the unit not cooling. When it does get fixed it will never be comfortable. 3.5 ton for a house <1900 sq ft. In a brand new home a 3.5 ton should be about 4000 sq ft if not larger. If this in the basement or attic? Is it mounted on top of a furnace? Maybe a lot of air is leaking around the base of the coil.
Is the outdoor unit running continuously?