I think the last two posts actually explain what Nissan considers to be correct operation. According the what I've read and experienced in other vehicles, the compressor will come on when you turn to defrost. It will STAY on even after you turn off of defrost to other modes, even if the A/C button is off. To "reset" the system you have to turn the vehicle off and back on, then the A/C button should function normally until you turn to defrost again. I think this is rather strange, but at least it is documented this way.

I WISH mine worked this way. Unfortunately in my vehicle, and at least one other new one, the A/C button seems to be hardwired ON, even thought the light toggles on and off. Personally I think its a simple matter of some wiring being messed up, but I get the explanation that this is normal.

For anyone interested, there is a simple fix to disable the defrost from engaging the compressor. There's just a small switch behind the mode selector dial that engages when the knob is turned to defrost.

I've already experimented with this switch and unfortunately it affects nothing in my vehicle. Neither does the A/C button for that matter..

Kurt