Yes after I shut my machine off if the thermostat is still calling for cooling I will turn the key switch on but not start the machine the fan will run until it cools off enough to satisfy the thermostat preselected temperature.

 

wait a sec.. you saying yes to my question of whether the fans stay on when the machine is only running or do they only work if they are at least in accessory position?
There is potential problem with wiring a manual in if fans stay on no matter if key is in accessory position or not from stock thermo switch. Having a manual switch that works while key is off could easily become a dead battery as because if the temp of the machines calls for the thermo to be on when machine is off you won't know which is causing the fan to be on. Walking away expecting it to go off is accident waiting to happen. I can't believe people would have not noted such potential problem so I will assume the fans don't work unless they are at least in the accessory position.

 

You are correct. The fan will not run if the switch is off. I will turn the accessory switch on after a few minutes of the engine being off as to cool a little more while stopped and taking a break. I just do it for piece of mind I guess. It is not like automobile electric fans that will run after the switch is off. Sorry I should have been more clear.