Old post I know but I recently bought a 2001 frontier having somewhat of the same issue except the compressor isn't engaging. I plug on my gauge its in the red, checked compressor clutch, its not locked up, squeezed the relay a little with a pair of pliers, the clutch engages, possible relay issue? Not fuse issue. Sooo being my country self I grabbed 2 blue male wire ends and a wire, removed the relay and jumped it out, now my ac nice and cold. I know I know some will say oh you will burn up your clutch or compressor, oh well its 19 years old, and my AC is cold for now. Also after I did this the compressor gauge showed the proper amount of gas was in the system