My (new to me) 89 Conbrio has two blower switches on the dash, but only one is connected. The fan is mounted in the transom and takes air from the rear of the bilge to one of the four ports in the transom. Previous owners hacked away at the original ductwork so I can't tell what the factory configuration was.

Any advice on whether there were two original blowers and how they vented?

Thanks,
John