In an interview, I picked up some background noise from the AC units. Can this be eliminated in Final Cut or special software. It's constant a specific pitch.

Assuming you're on a Mac, Soundbooth, includes noise reduction software. You copy a slice of audio with noise-only, and apply it to the rest of the clip. Sometimes it works well. Sometimes not. Too much processing makes voices sound underwater. It's often best to leave a bit of noise and cover it with music or other background sounds.