Possilbe Heater Core Issue
 

So just some background. I have a 2003 350 with 135k miles, and recently my radiator core was busted so I bought a new one. while I was at it I bought new cooling hoses. I put all the parts in and did a flush of the system and it seemed like I got all the air out. It worked great for two weeks.

Now for the past week whenever I shut my car off and it sits for about 45 minutes or so all the windows including the hatch, are covered in moisture on the inside. When I turn my heater on to about 80ish degrees it blows cool air. Now if I put the heater all the way at the end it blows very hot air. Even hotter than the 90* it says. If I back the temperature off only one click cooler it just blows cool air.

Is this just an issue with me having air still in my lines or is my heater core gone out. Anyone have similar issues..
Thanks for the help..

Do a pressure check on your cooling system and while it's under pressure, check the area around the heat exchanger for leaks. Finally, check for drips around the blower unit and the evaporator. If your car's heat is changing so dramatically by one click, your intake sensor (basically, a resistor) may be damaged. Follow the FSM trouble shooting guide. You can download your FSM here:

http://www.nicoclub.com/FSM/350Z/coupe/2003/