Originally Posted by thesignlady
They are cold air intakes. Necessary for proper furnace function ☺
In my '74 Sov, the furnace has two round vents on the outside of the wall behind the furnace: one is a fresh air intake, the other is the hot air exhaust. This system is quite common in all the AS TTs I have seen. No further venting required.
I, too have a vent in the bathroom (in my TT it is on the wall beside the toilet). However, it is for fresh air only, and I believe its fuction is to lessen the impact of "other" (non-furnace) gases. There is a piece of wood that may be slid across it to block airflow, in cooler weather.