As a sysadmin at a public university in 2006 the server room was a closet with an AC unit on the roof.
Occasionally the AC unit would freeze up, overheating the ~20 servers.
Monitoring solution was a network attached temp sensor, with a perl script monitoring it and sending alerts to an AIM (yes) account connected to an SMS gateway that would then page my flip phone.
And I have the code still, https://gist.github.com/ecliptik/86e77e0f68b96517a7643e8997e9caef
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