Yep..my 04 Titan crew 4WD LE did same thing. VERY COMMON. Dealer should have tech bulletin on this problem and nissan will almost always fix it at no or little cost. My extended warranty took care of it ... AC Vent control servo under dash on passenger side. Dash has to be removed to fix. I have been a tech for 15 year an d specialize in nissan on the side. Takes me 1hr to R&R CAREFULLY. MANY DELICATE PARTS. I would not recommend a novice try it.... Can remove glove box to fell if its the AC servo clicking and making noise OR Also servo right next to throttle pedal at base of duct for rear heat control door will strip its plastic gears and click and pop. Hope this helps some.