And if they're smart, that's exactly what they would do. If these cats are indeed feral, and there's no way to "seal up the entrances" the supply of cats will not end even if you got rid of every one of these. Putting the equivalent of the "steam grate" just above the exhaust ports solves the issue (as well as something in front of the intakes to try to filter the hair, too).
You won't beat 'em, so come up with a win-win (and having cats to keep mice from your wiring is a win).
As a side note, I live in an area where agriculture is still "a big thing" and, like in so many places, the supply of feral cats can easily exceed demand (which is effectively zero). One of the local SPCAs has launched a program where they will supply neutered and health checked feral cats to anyone that wants one or more. Farmers love having "mousers" around that require very little care beyond feeding and watering otherwise. They even have a local TV ad for the program.