My first discussion of this was lost in the mixup so I will start with a recap.
I noticed that it took forever for the electric fans to come on. From what I read one will come on at 212 degrees and the other a little warmer than that. This did not seem quite right to me seeing how we place such an emphasis on keeping the engine cool, especially the non-EGR 1992'* like mine. I did not like the idea of the fans coming on some 30 degress after my 180 T-Stat opened up. At first I was going to install a switch for the fans as that seemed easy enough, but I wanted the convienience of not having to remember to turn the switch on or off. So I thought why not install a variable thermostat to control the electric fans. That is what I did today.
I will briefly recap the install, but I I can write up a more detailed tech article if there is enough interest.
I purchased a Hayden variable electronic fan thermostat at Pepboys for $39.99 + tax, it the same as the Derale unit 16759 here: http://www.derale.com/electricfanaccess.shtml
I was going to purchse the thermostat from Summit http://store.summitracing.com/partde...57#largerimage
, but I was walking through Pepboys and seen one on the shelf so it saved me the dealy in shipping and a couple bucks on the hangling charge.
The install is very straight forward. You basically follow the directions. The only exceptions I made were I wired a switch inside the passenger compartment that is tied into the AC Compressor wire supplied on the thermostat. You do not need to connect this wire to your AC Compressor as the fans are already wired to come on when the AC is on. Not needing the wire to turn the fans on with the AC I decided to make a better use of it than leave it dangle. Now I can flip a switch and the fans will come on whenever I want, even with the engine off, but you can wire it so they will only come on with the ignition on.
The other thing you will have to do is change the polarity of the fan switch output source on the thermostat. The polarity of the output on the thermostat is positive and you need to change it into a negative signal to switch the relay on and off. This is very easy to do with an additional relay.
I tied into the relay that turns both fans on at the same time (green wire on the back of relay farthest to the drivers side). I chose to tie into both fans versus just the low speed fan because I wanted maximum cooling ability. This proved to be the right choice because when the fans do kick on they do run for a fair amount of time. I'm guessing the low speed would never have cooled enough to kick the fans back off again.
I have it set up to turn my fan on just below 200 degrees. They will run for 30 seconds to a minute and shut off again. Now I don't have to worry about the car getting too hot at idle or sitting in stop a go traffic. And if I feel like I need some extra cooling I just flip a switch and I am all set.
Install took me 2-2.5 hours and it was not difficult at all. On a scale of 1-10, this project is probably a 5 for the average shadetree mechanic. For someone a little more comfortable with electronic installs this is definitely a walk in the park.
I can take a few pics of my mouting locations, the temp probe, and my electrical connections for anyone who is intertested. If you would like more detail feel free to ask.