Electric radiator fans - power source?

[AJs72K5]

I'm running dual puller Flexalite fans. The PO wired them to a 12V constant power supply letting the thermostat dictate when they are on and off. They tend to keep running for a while after the engine is shut down because the engine's still hot (duh). Are there any reasons I couldn't, or shouldn't, wire them to an ignition power source? That way when the engine is off, they're off. Thoughts anyone?

 

[4X4HIGH]

Most factory electric fans are set-up that way. Regardless of engine on or off the fans may come one if the temp is hot enough. Nothing wrong with wiring it so they will only work when the engine is running but it's always nice to be able to have the fans cooling the engine when it's off if say for instance you were having some overheat issues and had to stop and turn the truck off.

 

[DPI]

I am using a flex-o-lite controller for my fan. It will run 5 seconds after the motor has been shut off. I do have two switchs, one will turn the fan on, the other will overide all other operations and turn the fan off. It is handy for water crossings or if I am working in the engine compartment.

 

[NewUser]

i wired up my windstar fans thru a Hayden Thermal controller and ran the 12v ignition wire to my fuse box to a fuse thats only hot when my switch is on...fans kick on at 195 and off at 180

 

[dyeager535]

Just to clarify, you'll want to pull the power for the fans from the battery (constant) and since a PO wired it, I can't assume it was done right, with relays...so you trigger the relays with an ignition switched source. You still see people wiring the fans straight through switches.

I don't like fans coming on later either...not like I put my hand in there, but don't need the adrenalin rush when they'd surprise me while underhood.

 

[GNERGY]

I pulled power from the hot terminal on the alternator and ran it thru these relays, and the power for the relay coil is fron the ign. hot on the fuse panel. The big fan comes on with a temp switch in the water pump and the small fan comes on when AC is on or also can be turned on with a toggle switch Pics included
Tarey