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post #5 of (permalink) Old 04-23-2009, 12:59 AM
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I've covered this a bunch of times on other forums...

And it's back to basics!

What kind of driving/wheeling do you do,
And what do you expect out of your system?

First off,
Circuit protection is MANDATORY, and CRITICAL in some applications!
I use self resetting circuit breakers instead of fuses.
Every time you forget to turn the fans off and hit deep water, you are going to hit the circuit protection!

Fans can suck up to 70 or 80 amps when you drag them down in water, so roughly a 15 to 30 amp breaker is a good idea.

If you use fuses or fusible links, you are going to spend a BUNCH of time changing fuses if you do water/mud a lot!

Don't forget a 'Oh Sh!t' light/buzzer!
Just like you will forget to turn the fans OFF,
You are likey to forget to turn them back ON when you clear the water/mud, and that can get SERIOUS QUICKLY!

I use a low oil pressure/high temprature light and buzzer,
(buzzer because I don't watch the gauges/lights when I'm wheeling! Most people don't!)

That light/buzzer will tell you when to turn the fans back ON after you turn them off, and just might save your engine in the process!

Do you want to use DUAL fans, or have a 'Soft Start' on the fans?
Dual fans can come on staggered so they don't draw a bunch of amperage all at once with them both starting at the same time,
'Soft Start' is reduced current to the fans to start them slowly, then direct current to them for maximum cooling speed...

Now, What I have is fans that turn on automatically (redundancy, they turn on no matter what unless I command them 'OFF')
Saves an 'ON OVERRIDE' circuit...

And I have a switch to turn the fans off when I want them off... Good for water/mud fording mostly.

Consider an automatic switch hooked up so it turns the fans ON/Off (unless you override) automatically when you hit deep water.
Like a sump pump switch with float,
Or a boat bilge pump switch,
It would interrupt the fan relay circuit when the float gets into enough water that it 'Floats'...

Consider DUAL fans for redundancy if you wheel off the beaten path.
'76 forward Jeeps have a radiator that accepts Ford Contour (Taurus, Topaz, ect.) DUAL fans really well,
And the fans are COMMERCIAL GRADE, not the cheap crap you usually get from the parts stores.
They come with good (Water Tight) connectors, and they fit like a glove.

If one fan quits, you can 'LIMP HOME' on the remaining fan, and all it costs you is an extra relay (about $12).

I have a '73 jeep, so it has a 'Pusher' in front of the radiator, and a 'Puller' in the back of the radiator.
One is a Hayden I purchased off the shelf at Advanced Auto, the other is from an '89 Cadillac and it works well!
Since the radiator is smaller in the early AMC Jeeps, I couldn't use the Taurus/Topaz/Contour fan set, although I've put a few in for other people...

So let me know what you want to do, and I'll try and link you to some wiring diagrams that will help you out.
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