I have the same noise. Noise when I have the fan speed on 1. I know that it is the fan motor (brushes or bearings) making the noise. The dealership said the "fix" was to add some insulation to mask the noise. I told them that it wasn't going to FIX the problem, but I let them do it anyway. Long story short, the noise is still there. There are trying to talk to Nissian Technical Service to find out what to do next. Oh yeah, my friend's Pathfinder does the same thing. Nissan needs to find some better motor suppliers!
They replaced the air/mix door and now the problem is back. It seems like it is worse when the car sits out in the sun for awhile.... The clicking is unbearable and it almost sounds like a vacuum problem when you turn the fan on Auto.
Back to the dealer today to try and resolve the problem... apparently they have their "Master Mechanic" talking to Nissan about it.... my confidence in Nissan is growing shorter every time I have to take the car back in....
I had a squeaky/clicking sound coming from my fan during the winter. It was really annoying....it was just the right pitch that you could here it cut through the stereo with the volume up. It would happen on the first two speeds and go away if you turned it up..
Needless to say, I knew the sound was a bad fan motor (sounded like grit in the bearings or a wire brush against metal - very slight though). Took it to the dealership and they said they didn't here anything. As soon as I got in the car it was there clear as day. Had them sit in the car and trained them what they were trying to listen for...they heard and ordered a new motor. Ever since, no problems whatsoever!
If the noise you have disappears when you turn the fan up, take it to the dealer and have them replace the fan/blower motor.