ac vacuum vent

[Thingymagigercarpart]

hello,
on my 95 w124 e300, the out side air still blows when the system is shut off does anyone know the vacuum hose number that's located under the passenger dash that I induce vacuum and plug it for a quick fix , or if it is not located there, how would I be able to stop the air from blowing in when the system is off

sincerely magiger