I was using something I got from a japanese car wrecker, it's just two leads (make contact when temp reached) and it screwed straight into my thermostat housing (I know it's not the best place, but it was soo easy).
Anway after 3 years it's stopped working. Time to do it properly, before the fans would switch on once the engine was up to temp and not stop until the thermostat closed.
I drove the haast pass yesterday without the fans working and no overheating, so it's not too big a deal.

I have manual AC fans I can still switch on when needed.