Wiring a manual fan override switch.

[Robclio98]

As above I'm wanting to wire in a manual override switch for the fan.I've done a quick search but nothing has really come up,

So what's the best way to do this?? Straight to the fan or before the relay and fuse? Has anyone got a guide?

Also does it make a difference that I'm running a stand alone ecu?


Cheers!

 

[Robclio98]

Anyone?

 

[bigmonmulgrew]

Why would you want a fan override?
Are you trying to get it to come on all the time?

If this is the case I'd use a voltage sensing relay.
Set it to 12.5 volts and when your alternator comes on and your voltage comes up slightly it will turn it on. It would probably run on slightly after turning the engine off too while the voltage settles, only a few seconds I'd imagine though.

I use one to connect/disconnect my second battery so that auxiliaries only ran on the second battery when the engine wasnt running. That way I could never accidentally flatten the battery.

Suppose you could just wire a relay into the ignition though

 

[Robclio98]

Just for when I'm sitting in queues, or come to a stand still after track... Just so if the fan doesn't kick in I can flick a switch and make it come on

 

[bigmonmulgrew]

Surely if sitting in queues the fan should come on anyway if the temp gets high.
If its not coming on surely somethings faulty.

If you want it to come on at a lower temperature you could always use a thermal switch
http://www.ebay.co.uk/itm/THERMAL-S...al_Components_Supplies_ET&hash=item2c64582e70

although the ones I found in this price range are closed circuit below the set temperature so would require some additional wiring. If you could find one thats closed circuit above set temp then it would save you some wiring

 

[bigmonmulgrew]

Just found an open one
http://www.ebay.co.uk/itm/Thermal-C...Supplies_ET&hash=item1c25a4cbf7#ht_1797wt_905

You may want a lower temperature if your wiring it outside the pipework. say 70C or even 50C.

This one would be very easy to setup, just need to find the right temperature/mounting position.

 

[bigmonmulgrew]

that was in a search for "thermal switch norm open" by the way

 

[Robclio98]

Cheers mate il check them out

 

[bigmonmulgrew]

Using a thermal switch should make the job much easier since there will be no running of difficult cables into the dash, and you have the benefit of it being automatic. You could wire it directly into the battery (fused of course)
Just bear in mind if you do that it will drain the battery a little since it will run on after turning the engine off.
I doubt this would be a problem if you have a decent battery just bear in mind that the water pump wont be circulating the water with the engine off so if you put the sensor somewhere that will take a long time to cool even with the fan running you will probably drain the battery.