Will the NAV screen display the audio and HVAC stuff without the trunk unit installed ?

Considering a conversion to a NAV from non-nav, and I have access to a screen and controls but no trunk unit. I would consider a partial install if the display is usable without the trunk DVD unit.

 

the only thing you would be able to do is power the screen up and hook a dvd player up to it, but you would still need the converter