Electric Fan Install Q

[got_boost!]

Hey guys. Just replaced my ridiculously heavy and parasitic stock cooling fan with an extremely nice 16" electric unit and a thermal switch. Everything works great, car is cooler than usual, and the install was pretty straight forward. Deffinately a mod I would recomend for it's cheapness and increased engine response.
ANYWAYS>>> After I finally got the thermal switch tuned in to where I want I ran her around the block and it kicked on and everything was cool and great. However when I got home and opened the hood it turned out it wasn't my new electric fan running, it was that stock electric fan that's mounted in front of the rad. I can turn the thermal switch to a lower temp setting so that the new fan kicks on before the stock one, but it's way too soon and too frequent. If I put my switch to where I want it, then that stock fan kicks on loud as hell before my new electric has a chance to kick in and will run non-stop keeping the engine too cool for the thermal switch to start my new fan. I don't want to leave cooling responsibilities to that loud, heavy stock electric that I wanted to pull right out anyways.
Can someone please tell me why the stock electric fan keeps kicking on even though my temps are extremely low to begin with (it'll kick on before I even get half way up the temp guage). The obvious answer is just to yank it, but I'd like to know why it's happening in the first place since in eight years of owning the car, I can honestly never remember the thing turning on. Thx.

[johnnyjohnny]

Not sure which fan(s) you're talking about. Do RB20det's have both a clutch fan and an electric pusher fan? The only electric fan on a stock motor that I know of is for your AC condensor. Don't mean to ask a stoopid question, but is your AC turned off?

Also, where do you have your thermal switched sensor installed? It's important to install this in the right location, and have the switch set according to your thermostat, so your water pump and electric cooling fan aren't fighting each other to keep your motor at a set temperature. I know it took me a while to get mine dialed-in properly.

[DarkCaporaL]

RB26s have a sub-electrical fan that is mounted in front of the AC rad. It operates off a thermoswitch which normally makes it start once engine temperature reaches 90C.

I don't think I've ever seen mine work, and I'm too lazy to check it. My temps are always between 75-80C...I can maybe see this start if you're sitting in traffic and it's like 50C outside.

I have no clue about Rb20s or 25s.

EDIT: To the OP, sounds like the thermoswitch may be faulty as the fan starts too soon. You can check the manual, page EN-252 for diagnosis, however it requires heating the switch and monitoring the temp which is a PITA. DO you have an aftermarket water temp gauge?

[got_boost!]

Thanks for the replies guys. Yes the thermal switch was in a good spot, but further testing also showed it was faulty. I do have an electric pusher fan stock up front, which as you said seems to kick in whenever the engine gets a bit too hot. I do have AC but it doesn't work and no my AC wasn't on I ended up wiring it to a rocker switch for the time being till I could find a suitable thermal switch replacement. As for my water pump and fan fighting eachother?!?! Your pump pumps and your fan blows. You can control when your fan blows but not when your pump pumps. It's a pump. The only other thing controlling the cooling in your car is your thermostat.