Theory - Perhaps the bigger, multi-blade fans used with the fan clutches are not engineered to operate continuosly at high speed and will disrupt the airflow somehow (cavitate?) if the fan clutch is seized. The clutchless fans I've seen have always been smaller, with fewer blades than the clutch ones.

Related trivia - I'm in the Sunbeam Club.(Remember the British '60s Sunbeam Alpine & Tiger sportscars that looked somewhat like shrunken '55 T-Birds?)
Recently, one of our long-time Sunbeam gurus did a cooling fan test, comparing the factory fan to various aftermarket metal and fiberglass flex-fans and electric fans and the winner was (drum roll please) the cheesy looking stamped steel four-blade stock factory fan!

Happy Motoring, Mark

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DrDKW