Another question.... 97 Blazer. Heater problem

[Lovemy97Blazer]

I have another question. The heat (or cold air) will not switch from the low stations to the high stations on my dash. I can turn the dial to change where the air comes out of but the air doesn't change locations. I am told that there is a vacume hose behind the dash that may be broken and not switching properly. Is this an easy fix? Has anyone else experienced this and fixed it?

Thank you,

-Andrew