What I would expect under the circumstances you describe is that the knob controls the temperature at which the fan turns on and off. It sounds like the buildin

What I would expect under the circumstances you describe is that the knob controls the temperature at which the fan turns on and off. It sounds like the building installed the wrong device for the job, or didn’t hook it up properly, or it’s otherwise broken; hard to tell from the article which of those options it is.