Morning Don
I'm assuming that there is a switch on the ignition panel that has you curious if not, bear with me. Quiet a few of the older boats were using a common ignition panel that were used on diesel and gasoline engine boats. The blower was primarily for gasoline engined boats to exhaust any gas fumes that might exist prior to cranking the engine and blowing the boat up. Diesel fumes if any are not flammable, therefore, a blower was not necessary and the switch is not hooked up to anything, just there. Do you need to exhaust the engine compartment, no, but you can if you want to, won't hurt anything.
