My Nissan rouge heater is not heating up properly on drivers side vent.

It is almost certainly the common stripped out blend door problem. The Nissan Rogues from 2014 to 2020 and all the Nissan Rogue Sports have this problem. It is very expensive with the dealer to get it fixed with the same faulty parts. Check out this company they have a repair kit to permanently fix that problem. Also some information on diagnosing it. renegadesolutionscompany.com