I am thinking about buying a '94 Sentra 4-door with the 1.6 liter. Apparently, the AC compressor is toast. I have a spare AC compressor off a 91 SE-R that was working when it was pulled. Can I replace the compressor on the 94 Sentra 4-door with this one from a 91 SE-R?

yes, it should bolt up in the same location.I dont remember hearing or seeing that there is a difference