Nissan Repair: vent, automatic climate control, expansion valve

Question
.Sometimes the fresh air vent close when the ac is running . Then it warm air coming out.I turn off ac the ac the vent open. What's the problem.

Answer
Brian,

Do you have automatic climate control?  If so, the computer is going out.  That is the display that you adjust, behind the display, and part of it.  If yours is manual we might need to look at something else like the evaporator freezing over or the expansion valve being stuck.