Just a bout the centre, underneath the back of the engine, if I remember rightly, it goes through a clip on the pull start and up to a bullet connector, on the 350 and 450 this is on the RH side, not sure about the 400.

 

Does it even need a fan for the oil cooler? My 1989 350 Yamaha 4x4 is still running great for my friend and that ATV never even had fan assist for it's oil cooler in its 17 year run time.
The Foreman 400 only has a 47cc bigger motor , I'm sure it does not run any hotter then a Big Bear.
My 250 Yamaha Moto4 never even had a oil cooler or fan.

 

i found the blue wire and disconnected it and fan still runs, im thinking the module is bad but i think i will just pull fuse and not worry about it or else put an inline switch to turn on if i think its hot, One other note, right before this happened the battery had a battery charger on it and i think it was left on to much and the battery got very hot, so i replaced the battery, thanks for comments

 

It depends on what you are using the bike for. I know of one person who leaves his bike idling for ages rather than switching off, his fan works a lot. Many farmers use quads for mowing and chain harrowing, the fan comes on then. If you think you may get the bike hot enough to need a fan, let it run, better to be overcooled than too hot and seize. Those bikes that "never needed a fan" were designed that way, with big cooling fins and low power outputs.

 

My 350 Grizzly has both the Fan and oil cooler yet has the same 348cc that Yamaha has been using for 30 years in all of its 350 class dirt bikes and ATVs.

My fan does come on my2007 350 grizzly a lot but I have put my no fan 1989 350 Big Bear through the same condition and it never misbehaved once and it's oil cooler was smaller.
The motors had the same size cylinder fins. I'm not sure how important the fan assist on the oil cooler is.
The oil cooler still does its job even without a fan just by letting the oil circulate outside of the crankcase for a short period to cool off a bit.