@darkling @stefano
Until one morning I arrived to chaos. One of the aircons had failed, & the others, overstressed, had completely iced up, and the reduced airflow had caused the temperature in the room to rise. It was pretty much the hottest I'd ever encountered anywhere!
Fire doors and internal doors were propped open, to get a bit of airflow, and the blocked air cons turned off. The heat then had a chance to melt the ice, and they could be brought back online later. I think it took all day.

@darkling @stefano
Ferranti Computer Systems, Cheadle (UK) circa 1982. I was a lowly apprentice, at the time working in the department that oversaw the various VAXen that most of the site used. Three full size machines and a handful of microVAX. Kept cool by *three* massive air conditioner units on the external wall. The server room was always chilly. /cont