Leaky Roof

:( I am having trouble with a leak around my air conditioning unit on the roof of my class C motor home. I have had an RV repairman try fixing it 3-4 times. It still leaks! I had some work done on the roof to support it in the center, they used 3" steel angle material to lift the center of the roof up. This gave the roof a nice curve, which does make the water run off. However, the air conditioner still weighs down a little in the center. I would appreciate any suggestions anyone might have to fix this problem.