My 'Bird is wired direct - doesn't turn off when the ignition is off. But that's because it has a carburetor. If I don't have a way to exhaust the heat from the engine bay the fuel will boil in the carburetor causing flooding and fuel spill issues.

My Montero Sport is wired into the ignition - everything is off when the ignition is off. But my Sport runs a Spal electronic fan controller and I don't want the controller on 24 hours a day, 7 days a week.

I've seen setups wired direct drain a battery to the point the vehicle wouldn't start. Lots of really short trip, start and stop driving in hot weather with a cheap battery.

My 'Bird fan will run for 10-15 minutes after it's shut off when the weather is in the mid/high 90s. Once in a while even longer. The ideal setup would be a timer - run for x minutes after key off and then shut off.

Depends on what you're trying to accomplish, I guess.

Edward