best wiring for electric cooling fan, Ford V6

[micha]

i´m converting my wedge from viscous to electric cooling fan at the moment. fan is fitted, adjustable thermostat is ordered. the only thing i´m not sure is how to connect it electrically:

i definately don´t want to connect the "+" directly to the battery (with a fuse).
my idea is that the "+" is only active with ignition "on".

any advice where to connect the "+". do i need a relais? the thermostat-contact can switch up to 15A.

my car has the black wiring loom with all the electrics, relais and fuses under the bonnet.

[wedg1e]

In that case your fuse box won't have any spare fuses. You could choose a fuse which doesn't protect much (eg clock, hazards) and use that to supply the relay contacts, while the relay coil + side takes an ignition feed from some convenient point on the fuse box that is 12v with ignition on and the coil - side goes to the thermo switch and then down to ground.

My car has a permament 12v feed to the relay contacts so that the fan will run with the key out; the fan stops when the thermo switch cools down.

[GreenV8S]

I don't know what stat you're buying, but there are standard fan installation kits available which include the stat, loom, relay, fuse etc. If not you will have to source the parts and assemble the loom yourself. You will definitely need a relay since the stat won't cope with the full current taken by the fan. You will need a good 12v supply. The start motor solenoid is often a convenient place to take this from.

[micha]

i use the very common adjustable thermostat, absolute identical to the ones from Spal or Kenlowe. the fan comes from a modern car (bought it for 20,-€ at ebay), its mounted behind the radiator and it sucks.

(The day a LUCAS product doesn't suck is the day they start making vacuum cleaners..lol)

why do i need a relais? the thermostat-contact can switch 15Amps!!!

www.limora.com/index/lang-1/lkz-176/markenid-1/katnr-178/katnr-169/kat_sprache-2/lang-1/hrubnr-1362/rubrik-3869/functiontpl-artikelresult_zoom.tpl,,search-202250.htm

http://cgi.heuten.com/cgi-bin/Webshop

www.racimex.de/content/de/quickfinder/pricepopup.php?art=70600&referrer=auto%2Fracimex%2Fventilatoren.php

but here comes the same (without fixing bracket) for an extreme low price:

www.conrad.de

search for item no (artikelnummer):615889 - 62 or 615889 - LN

Edited by micha on Saturday 20th January 13:53

Edited by micha on Saturday 20th January 13:57

[GreenV8S]

That's similar to the stats I use, although mine don't say 'Kenlowe'. It's your choice, but if I were you I'd use a relay. 15A isn't much, some fans draw much more than that when they're running and remember the current can easily double as the fans come on. Even if the stat takes the current, you're better off using a cheap replaceable relay rather than have to buy and fit a new stat when the contacts burn out. Using a relay also means you can supply the control circuit from any convenient ignition switched source and take the main power directly from a high current source such as the start motor terminal.

[wedg1e]

The 'stat may be rated for 15A, but that'll be 15A resistive load. A DC motor is an inductive load and making/breaking the current tends to cause a lot of arcing that fries the contacts. Better, as Peter says, to have to replace a cheap relay than an expensive 'stat.

[micha]

thanx for your advice....so i will use a relais....