A/C vac issue

[Stihlindixie]

I've obviously got a vacuum leak somewhere because its not blowing out the center vents. Starts out coming out the center but after a few minutes resortes to the defrost vents. Has anyone ever had this?

Also the trans is shifting hard. I've checked the lines and all are connected. I did replace a fan belt last week and after that everything started.

Does anyone have any advice on what lines to check?
Thanks!!