The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - How to wire electric fans to stay on for a few minutes after engine is shut off?

**VetteVet** · 11-16-2017, 10:41 PM

In my opinion it is a waste of time and energy to run the fan after the engine is shut off.
The fan will only cool the liquid in the radiator because the water pump will not be sending fresh hotter coolant into the radiator. The cooling effect will be done by thermal conduction from the hot manifold coolant to the radiator until the thermostat closes, and what can cool from heat flow from the water pump. This will take some time and it will cool anyway as the engine block cools.
I would just rewire the relay to shut down with the key and the cooling sensor.

Does anyone know if the car manufacturers are setup for the fans to run after engine shutdown?

11-16-2017, 10:41 PM	#5
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,703	Re: How to wire electric fans to stay on for a few minutes after engine is shut off? In my opinion it is a waste of time and energy to run the fan after the engine is shut off. The fan will only cool the liquid in the radiator because the water pump will not be sending fresh hotter coolant into the radiator. The cooling effect will be done by thermal conduction from the hot manifold coolant to the radiator until the thermostat closes, and what can cool from heat flow from the water pump. This will take some time and it will cool anyway as the engine block cools. I would just rewire the relay to shut down with the key and the cooling sensor. Does anyone know if the car manufacturers are setup for the fans to run after engine shutdown? __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.