Radiator fans on, ignition off. - Alfa Romeo Forum
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(Post Link) post #1 of 5 Old 02-06-11 Thread Starter
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Radiator fans on, ignition off.

Hi all,
Was wondering if there is a simple way to allow the radiator cooling fans to be 'rewired' to allow them to carry on working once the ignition is off? It drives me mad that they will switch off with the ignition even though they were judged to be necessary just seconds before when the engine was running, surely if they need to be on they should remain on even with the ignition cold particularly as stopping will prevent any airflow at all and indeed increase the overheating and possible damage due to heat-soak. I have made this alteration to my cars in the past, but don't want to cause problems with the more 'complicated' monitoring/switching in a modern car. Thanks in anticipation.
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I've never really seen the point of running the fans after the engine has stopped... All it's going to do is cool down the coolant in the rad, as it won't be circulating any more.

I suppose there will be a bit of a cooling effect to the rest of the system, but the amount must be minimal.

I'd be interested to hear any other views though...
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My old Fiat Cinq fan runs on after ignition off and an Audi Coupe I used to have would regularly have the fan start up after I'd locked the car and walked about 20' away.. it was a bit of a shock the first time it happened...!!

I imagine it could help clear heat from the engine bay, but can't be needed otherwise it would do it already.
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(Post Link) post #4 of 5 Old 02-06-11 Thread Starter
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Cheers, I do take your point David C, but I do wonder why heat is an issue with some models/manufacturers and not others!? Mechanical sympathy has always lead me to allow my car to cool down properly (gentle last few miles, especially after enthusiastic driving) in the same way as I allow it to warm up fully before extending it. I just like the idea of being able to allow the fan cooling to continue after stopping. maybe it isn't such a problem but the heat was there before and I like to remove it, maybe continuing to idle at destination is the answer.
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The relay that controls the fans is actually wired to the "always on" 12v supply (it is the ECU that switchs off the fan) ... If you prise off the plastic cover of one of the relays you can manually switch it on even with the car off, so you could "frig" some sort of manual switch if you wanted to.

But as the others have said there isn't really much point ...
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fans , ignition , radiator

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