The AR-C Eclipse uses mercury as part of the system. The overheat temperature corresponds with mercury's boiling point (357 C), and while we don't definitively know the freeze-over temperature, it's going to be -39 C.
trufax --- Surely there's no problem with them putting me in Brawl, right? It's ****ing satire, damnit. It's speculation, but this isn't SSBB, so it's not moddable.