Switch/sensor for electric fan

OK, this might not be your standard fab question, but it didn't seem to fit in any of the other forums either, so here goes...
I am looking for a switch/sensor to turn on an electric fan. I want a temp switch that screws into the engine block, and at a predetermined temp provides a ground for the electric fan relay. I see all kinds of kits of this nature but can't track down a stock application for a switch. I have wire, relays, and the knowledge to wire it up and don't want to pay $50 for a kit just to get a switch that I am sure is just pirated from a stock application.
Surely someone here has the info I seek...

Thanks!

 

I used a Hayden fan control relay with adjustable temp control. it has a probe that goes into the radiator core.

 

any Jeep 4.0 will have a fan switch in the block ( or radiator, don't remember), at least on factory AC equipped models.

 

Might also look at '80's-'90's front wheel drive GM cars. Many of those had a thread in fan switch. Nickmil

 

I need one too, I figured with all the cars with electric fans they'd be plentiful in the junkyard.

 

Jim, all the research I've done on the Jeep 4.0 leads me to the conclusion that the temp sensor is a variable resistor, and the computer interpets the signal and engages the electric fan from that signal (on XJs with the electric fan). On AC systems I think the switch is in the heater controls vice a switch on the engine.
Like Nick and Hawkes said, there has got to be a switch out there that provides a ground connection at say, 180 or 195 degrees, that I can use to control a relay.

 

I've got one of these. Been working really good for a few years now. I did have to get the special connector to run it. I got it through AC Delco.

 

Scott, you don't happen to know a part number or year/make/model?

 

After some online research I'm finding that a lot of factory switches turn on at 225F or above, I'm just going to go with a new one that turns on around 180-190. That's hot enough for me. I checked a lot of wiring diagrams for cars like cavaliers that have fans, and as far back as '84 they had ECM's and the wiring comes from the ECM. Probably not what I'm looking for.

 

Greg, most of the switches I've seen, screw into the radiator tank somewhere. My experience is with mostly import cars though. How many water jacket locations do you have on your 4.0 to install one? Get us a thread size and we'll start looking for ya.

Check this out. http://www.hallspeedshop.com/cool-fan-switch-p-12665.html

 

my electric fan came with an adjustable control box.

 

No... I think I got it from a 82' Chevy Caviler with a four cylinder. The fan turns on at 210 degrees and shuts off at 195 degrees.

 

http://cgi.ebay.com/ebaymotors/TEMP...003QQitemZ130203433966QQrdZ1QQsspagenameZWD1V

 

The switch in the auction is what I am after, but I can wire my own relays and can't believe the sensor would be very expensive, certainly not 60 bucks expensive.

After quite a bit of research and thought, I am looking at another option. I have a 4.0 in my 83 CJ7, and the computer on the XJ 4.0s have a circuit that controls the stock electric fan on XJs. I am going to see if my computer has that circuit, which works off the factory coolant temp sensor, if it does I will use it. The factory sensor is not a switch type, it is just a resistor that varies with the temp, but the computer uses it to control the fan. It will make for a neat and clean install if my computer has that circuit.

Will update...

 

Wish I had seen this earlier as I did the same thing.

When I originally installed the 4.0 into my cj5 I used a taurus fan and one of those hayden adjustable temp switches. I think it lasted 6-9 months. I think they're junk.

After that I wound up using a later 4.0HO water neck that has an extra threaded port as compared to my early 4.0 water neck. I forget what the HOs use it for. Lucky for me we had a couple of old napa books at work and I was able to find a switch that turned on and off when I needed as well as having the correct threads. Works like a charm!

However, I no longer work there, nor do I have the book or know what sensor I used. Luckily, they use these temp switches for all kinds of emissions and fuel control stuff so there were quite a few to choose from. If your really interested in doing this you might go bug your local napa guy. You might also try searching the napa website and see if they list any info, I know they list a ton of rotor specs online.

Having said that a clutch fan is still the most reliable set up out there. I'm thinking of going back to it.

Kevo

 

After installing a 360 in my CJ5, last night I realized that the fan/fan clutch assembly when bolted to the water pump, will not allow the radiator to fit in it's correct position. I guess I'm now doomed to follow Greg's path and install a switch to operate an electric fan also. I'm going to the Borg-Warner website to see what they offer for these switches. My water outlet also has a threaded boss in it to put one of these. My question would be, would you include a relay in the curcuit to keep the heavy current draw off of the switch?? My sick logic tells me so Your thoughts???

 

Wire in a kill switch so you can turn it off manually. I tossed the original sensor/switch in favor of a simple on/off switch. I have a distinct dislike for things that are "automatic". I just keep an eye on my gauge and turn it on when I need it.

 

Definetly add a relay, hard to get a switch that would last to directly power up the fan, and you get to keep the high current away from the dash.

I have that now, just need a better memory.

 

Here is a picture of my set up. Up in the top right you can see the relay mounted to the firewall, its next to the power brake booster. Just left of the thermostate is the fan switch and the wires going over the radiator is for the dual electric fans.

http://groups.msn.com/ScottMilliner/scottsjeeppictures.msnw?action=ShowPhoto&PhotoID=430

 

What relays are you guys using? Ive been reading and getting some bad reviews on the little cheapie FLAPS relays. I need a 30amp set up that I hopefully wont have to replace every couple months.