Electric fans

[bopper85cj]

I'm thinking of converting to electric fans on my 85 cj. I read that the dual fans from the older Ford Contours work good and are a nice fit. My question is how are electric fans in the water and mud? I know that you can shut them off but at some point you need to turn them back on because of overheating issues. Can you just leave them on through the water. Thanks in advance.

 

[CJ]

You can leave them on in the water but the drag tends to cause big problems and I don't think any are designed to be run fully submerged. It's best to have a switch to just turn them off if your going to be water forging...

I wired up some for a friend one time that when they were turned off, it really just switched to a high temp switch, so even if he forgot to turn them back on - they still cam on automatically and turned on a big red light. Kinda like an idiot light but a little safer...

 

[TeamRush]

Use a LARGE self resetting circuit breaker on the way to the fans to protect the fans/electrical system when you drag them down in high water.

I use a 30 Amp breaker, and it seems to be just the right balance in size and cycling....
But I can't tell you about yours.

With smaller breaker, the fans drag down and pop the breaker when the get gobs of mud on them, or I go through heavy splashing that gets in the front fan.

With a larger breaker, the fans stay activated too long, and I get hot wires and cooked fan motors.

Around 30 amps is correct for my application.

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I control the GROUND to the fan relay to shut the fans off when I know I'm going into deep water...
Deep water means you don't need a fan running,
The water running through the radiator will carry off about 80 times more heat than air will, so when the radiator is submerged, even partially, my temp gauge usually goes DOWN instead of up...

By controlling the GROUND to the relay, you don't have a live wire running from fans to dash, and if the 'Ground' wire to the relay shorts out,
The result is the fans staying ON, instead of them going off and burring up the hot wire to activate the fan relay.
...................................

Anyway, I have a OVER TEMP and LOW OIL PRESSURE buzzer and light wired up, since I rarely watch the gauges when I'm wheeling...
The OVER TEMP light/buzzer has warned me to turn the fans back on more than once, and it's a good thing to have...
Simple wiring too! (We call it an 'Oh Sh!t' light!)
....................................

One thing I've been looking into is a 'Submersion' switch on my front end near the radiator somewhere.
A protected float/switch, something like a sump pump switch, to activate and deactivate the fan relays when I get into deep water, then drive out of it.

Sure would save me a lot of trying to remember the switches when I went into deep water and then remembering them again when I came out!
....................................

When my deep water fording switch is activated,
It also opens an air pressure solenoid that allows pressurized air into the axles, Transmission , Transfer Case , and distributor.

My distributor literally blows bubbles under water, instead of drowning out like it used to!
Takes VERY LITTLE AIR supply to do this, much less than you would think!

Air pressure on the same switch as the fan shut off keeps me from having to walk out of deep water, and I'm all for not walking/swimming when I don't have to!

 

[CJ]

I always forget to mention the circuit breaker aspect of wiring. Correctly sized breakers over fuses for any critical system is a must.

For example, I always use breakers instead of fuses for my low beam lamps, if a short happens in the electrical system - the lamps turning on and off is annoying but at least you can see to get home!

 

[coldwater]

There's some really good advice in there. Do you use a small aux. air pump to charge everything, seperate from a main OBA system?

 

[TeamRush]

I always forget to mention the circuit breaker aspect of wiring. Correctly sized breakers over fuses for any critical system is a must.

For example, I always use breakers instead of fuses for my low beam lamps, if a short happens in the electrical system - the lamps turning on and off is annoying but at least you can see to get home!

Yup, nothing beats a self resetting breaker for CRITICAL electrical functions!
If I were using the Contour fans, I would have TWO breakers, and have each fan on it's own circuit.

Redundancy is a wonderful thing!
With both on it's own circuit, you would only loose ONE fan and still have the second to 'Limp Home' on if something went wrong with one fan or one breaker, ect.

When you pull the fan down, you are creating a direct short in the wiring... And things start to heat up.
If you are smart, you have over sized wiring delivering electrical current to the fan, so the wiring won't be the first thing to get OVER heated...

The next thing to heat up will be the fan motor it's self.
Knowing the basics of electrical principals,
When the temp increases, so does resistance, and the current demand goes through the roof...
This would be the optimum time for your breaker to kick in and sever the circuit so the fan can cool off...

So when you slosh into some deep water situation,
(like last year we had flooding, and the local authorities asked us (off roaders) to rescue some old folks and search for trapped folks)
And current demand spikes because the fan is trying to push WATER instead of air...
A properly sized breaker will open the circuit before the fan motor or wiring burns up... And let things cool down...

Mine was trial and error for a while,
Then I just connected, then loaded my fan by rubbing a tool on the outside ring of the fan blades, and kept track of the motor heat with infrared thermometer and current draw with an ammeter.
My fans REALLY start to heat up around 22 amps,
And they go critical at about 33 amps,
So a 30 amp breaker does a good job for me.

Lets them drag down with a little abuse, mud, water, heavy splash, what ever, but when things get REALLY bad, the breaker throws and the fans get a chance to cool down.

Don't forget to use a SELF RESETTING breaker, or you will be under the hood a bunch trying to figure out why the fans don't work!

I got a 'Latching' breaker by mistake in one of my 'Experiments',
So when the breaker activated and opened the electrical circuit,
It wouldn't reset until you DISCONNECTED the breaker from the electrical circuit!
That was a pain in the butt!

Manual reset are a pain too, because you wind up getting out and raising the hood every time to reset the breaker manually.

I'd use a normal, NON LATCHING, self resetting breaker of about 15 amps for each fan, then go up or down from there,
Depending on whether the breakers 'Pop' at in appropriate times, or leave the fans 'On' too long when you wade off in deep water.

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There's some really good advice in there. Do you use a small aux. air pump to charge everything, separate from a main OBA system?

If you are asking me, No, I use an electric compressor and some fairly large reserve tanks.
I have one under body tank for the Jeep systems, but most of the time when wheeling, I have a second 'Carry' tank hooked up to the system in the 'Bed' of the jeep with the tools and stuff.

The 'Carry' tank is there so I can 'Lend' air to someone on the trail and continue on with my wheeling, or use the tank to air up trailer tires, air mattresses or what ever, away from the Jeep...

Here is an early diagram of my air system if you are interested,
http://www.civilianjeep.info/OBA/images/airsystem1.gif

Distribution block shown in diagram,
http://www.civilianjeep.info/OBA/images/switch03.gif

And here is the distributor that blows bubbles under water.
This was before the air solenoid, so it still has a manual valve in these pictures...
http://www.civilianjeep.info/OBA/images/AirSupply001.gif
http://www.civilianjeep.info/OBA/images/AirSupply02.gif

Usually the two tanks are PLENTY of reserve to keep the air pressure up when we are 'Fording' the jeep somewhere.

I keep up on seals and gaskets on my axles, Transmission , transfer, ect., so there isn't tons of leakage of the air pressure,
And the air pressure doesn't have to be huge, usually between 3 and 10 psi is plenty to keep the water out of my expensive synthetic gear lube!

The inlet for the air compressor is connected to the snorkel, so the compressor can run under water if it needs to.