No heat coming out of my far right passenger vent?

That vent is either disconnected behind the dash or there is a restriction in the pipe going to that vent.

This car does not have right and left climate control, I have seen the heater core clog up partially and cause this problem, I would remove the heater hoses to use a garden hose to flush the core out. Please go over this guide which can help show you how the system works:

https://www.2carpros.com/articles/car-heater-not-working

Please go over this guide and get back to us.