If there is some kind of geometric similarity between your 2-D and 3-D Models you can use BFINT command to transfer the temperatuere loads from 2D thermal to Structural 3-D.
That means your 3-D model is just an extrusion of your 2-D one. BFINT works for your case. All you have to do is to write proper node files for front and back faces of your 3-D model (assuuming 1 element thick) before interpolating from 2-d model.