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Discussion Starter #1
My 69 302 has electric fans on the radiator and they are controlled with a little box that has its own relay and potentiometer to set when you want them to switch on and there is a temperature probe slotted in between the fins right near the inlet hose. This all works very well and I have no complaints with it.

I have it wired such that the circuit is powered even when the ignition is switched off. So if the engine is quite hot from a lot of recent traffic, then the fans can sometimes switch on and off several times after I have switched off the engine.

Obviously, if I had an engine-driven fan, then it would not be spinning when the engine is off. Am I actually achieving anything as I guess all I am doing is cooling the stationary coolant in the radiator? I have been wondering to change the wiring to make them only run when the ignition key is switched on.

Do production cars with electric cooling fans run them if needed when the engine is switched off?
 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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A number of OEM's run the fans after the engine is stopped but not every time. I personally don't know the criteria to have them run or not after shutdown. If I were to guess, it would be to combat heat soak in the engine bay for whatever reason.

I had an old Ford that had a dedicated fan that would blow air onto the fuel injectors after shutdown when it deemed it too hot. We know what that was for. Because the exhaust was in close proximity and the excess heat could and would cause injector bodies to crack and leak. And set the engine on fire. Ask how we know for sure about that one. A Ford 4.9.

Time ago we had a Datsun 310 with a small fan directed at the carburetor. If the fan were disabled then in summer heat the fuel might boil (percolate) in the carburetor.

But both those aren't very good examples. They had specific and known purpose fans, they didn't just use the radiator fan.
 

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Many modern cars have electric fans that run when the key is off. And they have a warning sticker on the shroud that says something to the effect of: Caution- fan may start at any time. Obviously the engineers have deemed it beneficial to allow the fan to cool a heat soaked radiator even after the engine has been shut down.
 

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Discussion Starter #4
Thanks for the replies.

The more I think about it, I may just leave it as it is. Apart from a slight load on the battery, it is not doing any harm.
 

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I had mine wired like yours, on when car was off.

I got tired of hearing it after parking at a show or in my garage or at the mall.
 

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A little history In the early 80's Dodge 4 bangers came out with a Radiator fan time delay relay or an after run fan relay. The aluminum headed engine had a safety system to keep the damaging temps down after shutting the car off as engine temps will continue to rise for maybe 15 minutes .
The time running the fan was around 20 minutes after shut off as I remember. There was an ambient temp sensor I believe added to the circuit for activation.
Current hi perf aluminum engines may activate after a key off high temp conditions. It wont hurt to run your idea.
 

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Hey JRFox,
I just joined the forum and was searching electric fans to help me with my project. I also have a 69 coupe and just added dual 12-inch pull fans. I have had the fans stay on long after (20 min.) shutting engine down after a normal drive. Long before this, I always had the engine temperature go up high on my gauge after parking and shutting engine down for a few minutes. So, to help me, did you resolve your cooling system condition?
 

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Dakota Digital sells a controller that has a timer built into it for after you shut the car off, allows you to pick an interval and let the fan run without you worrying about forgetting to turn it off and killing your battery. It’s a pretty slick controller and until I went EFI was by my favorite one ever.
 

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Discussion Starter #10
Hey JRFox,
I just joined the forum and was searching electric fans to help me with my project. I also have a 69 coupe and just added dual 12-inch pull fans. I have had the fans stay on long after (20 min.) shutting engine down after a normal drive. Long before this, I always had the engine temperature go up high on my gauge after parking and shutting engine down for a few minutes. So, to help me, did you resolve your cooling system condition?
Hi there.

Just to clarify, I did not have any cooling system problems. My only comment was the fans can come on after I have turned off the engine. And they only came on 2 or 3 times for about 10 - 20 seconds each time. So no drain on the battery to worry about. This is how I wired it. I was thinking of changing the wiring, but I have decided to leave it as it is.

Jeremy.
 

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Hi there.

Just to clarify, I did not have any cooling system problems. My only comment was the fans can come on after I have turned off the engine. And they only came on 2 or 3 times for about 10 - 20 seconds each time. So no drain on the battery to worry about. This is how I wired it. I was thinking of changing the wiring, but I have decided to leave it as it is.

Jeremy.
Do you know what brand temp control box/relay/probe you have?
 

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Put an ON / AUTO / OFF type switch on it and you can use it or not. 'Merica.
 

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Discussion Starter #13
Do you know what brand temp control box/relay/probe you have?
Here are some pictures of the fan controller I am using. This is about 20 years old, so I have no idea if you can still get it and also I am not in the US.

It is dead simple to wire up and has a small temperature probe that slides between the radiator fins to detect the coolant temperature. You can adjust a tiny potentiometer to set the temperature you want the fan to come on.
760275

760278

760277
 
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