cleaning vents on a/c cab

[el_fantasma]

So I cleaned the vents on the driver side easily, lots of junk and no moisture. I went to the passenger side and saw this. I was told that this vent can be opened too but it doesn't seem straight-forward. I pulled on the lever between the vent and the vacuum actuator and the vent flexes a bit but doesn't seem to want to open. My AC doesn't work or I guess I could turn it on and watch it and see how it opens.

Can someone give me some newbie instructions - assume I know nothing.