Rad fans & manual switch

[rossins]

Hi
Looking for some help wiring in a manual on/off switch for the fans, to turm them on when sat in traffic before the temp gets too high. As you can tell my electrical knowledge is very limited. Any help gratefully received.

Cheers
simon

[stig]

There's a provision for this on the standard loom. It's detailed in the build manual (or see clive's wiring diag.)

[lvjost]

Hi Rossins,

It´s Nr 53 in the ultima wiring loom. 3 Cables, Green, Black/orange and Black. As usual black is earth...
as usual (in GB and Ultimasports) green is Plus. Black/orange is connected to the radiator thermostat, Nr 10 in the ultimasports wiring loom list....I don´t have the switch...I think there should be a relais or something...
For this questions the perfect help is [phone], ask for Dave..he´ll know !!!

[steve_d]

lvjost said:

Hi Rossins,

It´s Nr 53 in the ultima wiring loom. 3 Cables, Green, Black/orange and Black. As usual black is earth...
as usual (in GB and Ultimasports) green is Plus. Black/orange is connected to the radiator thermostat, Nr 10 in the ultimasports wiring loom list....I don´t have the switch...I think there should be a relais or something...
For this questions the perfect help is [phone], ask for Dave..he´ll know !!!

Unfortunately Clive's circuit repeats an error in the factory wiring info in respect of the radiator thermo switch. The black wire should be green.

Mode. When either the thermo switch or the over-ride switch are ON the black/orange becomes live to trip relay 4 and power the fans.
The over-ride switch used by the factory includes a light so that whichever switch makes the black/orange live also powers the light in the over-ride through the black wire.

I plan to change the green at the thermo switch to a permanent live so that when the ignition is switched off the fan can continue to run if the thermo switch deems it necessary. This will reduce any problems that may be caused by heat soak in the engine as I also have a fan in the side pod. (I will need to fit a diode in circuit so that the fans don't back power the ignition when switched off).

Steve

[canam-phil]

Steve

What have I not understood? How will your re-wiring solution reduce the heat soak in the engine (bay)?

I would think that the mass of the engine and its temperature would take the fan in the sidepod an age to cool by any appreciable amount. (As far as my fag packet calculation goes.)

Phil

Edited by canam-phil on Friday 18th August 18:21

[steve_d]

The fans, 2 uprated on the rad and a factory standard fan mounted in the side pod, will draw heat from both the radiator and engine bay, hopefully, until the temp drops below about 86.
Most of my journeys home end in only 1 mile of side street after leaving the motorway. After turning off the engine in my garage the temperature starts to rise rapidly and has even released the pressure cap on the header tank. I just want to take out some of that heat. On a warm day my Range Rover will start to run its fans after I have gone indoors and continue to run for 5 minutes or so. I expect the Ultima would do the same and may even do it twice as the water thermal siphons from the engine to the rad after the fans have cooled the rad first time round.

Steve

[canam-phil]

I cant see how it would thermo syphon. Engine hotter than rad so as hot water rises to top, the cold(er) would stay in rad. Or is that the wrong theory?