It could be individual employees causing problems. It’s not happening to every theater.
In my past life, I was a theatre manager. This was early 80s.
Employees do not have access to AC controls. Back then anyway. All the AC wall units were in a box with a lock.
I’ll bet now all AC systems are controlled by a central computer system, that I guarantee has log in and access restrictions.
It would have to be a manager. But they’d be cutting their own throats. Doesn’t make sense.