Been there, done that, got the T-shirt...  at previous work-place, the aircon in the server room failed one evening.  The first time our support guy noticed was the next morning, when she walked into the server room and thought "it's a bit warm in here". 

Took us a long time to figure out all the extra damage afterwards -- a lot of machines were less stable afterwards, and it often turned out to be down to a component suffering some heat damage.  Indeed, one riser card was found to be "welded" to the motherboard several months later (after we'd replaced just about everything else on that server...)

RAVEAC?  Redundant Array of Very Expensive Air Conditioners?