Previously we talked about monitoring the portable air conditioning unit keeping the server room cool. The SMS gateway, basically an overgrown Raspberry Pi, uses a USB decibel meter to report ambient noise volume in the room, from which we can extrapolate the state of the air conditioner's compressor and fan. The Sawtooth Power Mac G4 file server (and radio station) logs the temperature and humidity with a USB sensor of its own. The portable A/C unit exhausts warm air through a duct to the roof so the room can remain secure, and a turbine spins the hot air away into the atmosphere.
Unfortunately, what all this monitoring showed was the A/C unit was crapping out. The house central A/C's compressor died abruptly this summer after over two decades, naturally during the hottest part of the year, and it took nearly a week and $14,000 to get it dealt with (it was an old R-22 system and thus everything had to be replaced). The portable A/C was itself almost 11 years old by this time, and after that bad week running nearly non-stop started making an ominous unbalanced low warble from its exhaust fan. This got to the point where it was unable to clear its own condensate and a couple days where I had to empty the drain pan about every 12 hours, versus never having to before (not a great deal of humidity here). I like old computers, but I try not to accumulate old broken computers, and that goes double for old broken air conditioners. It was time for a replacement.