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Twin OEM Electric Fan Install Question


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My 89 4.0 2WD 5 Speed MJ just blew a water pump gasket. The PO "rebuilt" the motor 800km ago. I am less than impressed, everything leaks because he re-used the old gaskets. The Mechanical fan is bent, and I am changing the water pump, as I have to remove it to change the gasket anyway.

 

I have ordered 2 OEM Electric fans, my question is, what is the easiest way to wire them up? Splice them together and let the ECM control them? Or wire them through a relay to a switch and manually control them?

 

I have seen guys set up fancy controllers. I don't care if I have to manage them manually, I am just looking for a simple, idiot proof wiring job, as wiring is not my strong suit.

 

I live in Canada, so the temperature is generally mild, just wondering if anyone has experience with this install.

 

TIA

 

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This topic was just recently beaten to death discussed last month HERE.

 

If you don't want to use a "fancy" controller, put them both on separate relay circuits and control them with a couple of dash switches. Primitive but effective.

Thanks for the link, I did a search, didn't come up with that thread. Do you remember how much your fan controller cost? Maybe that is the simplest way to do the wiring.

 

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Take care when mounting your new OEM fans. Their shrouds have to be as close as possible to the radiator (no more than 1/4") w/o touching the fins to pull max air. A lot of guys mount up aftermarket fans with no shrouds and/or mount them too far away from the radiator fins, then wonder why they can't stay cool and start badmouthing electric fan cooling. THIS setup has worked well for me for many years.

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I put 2 factory AC fans on my Master Jeep. I spent time making wiring control all fancy. 3 Thermo sensors, Relays, in cab switch. Set them up, to where one kicks on at ~180, 2nd kicks on at ~200. Turing on AC kicks them both on. Manual cab switch turns them both on. 

 

What I have learned. 

 

Best to wire one to always run when engine is on. Wire 2nd one to simple 180 sensor. Have backup switch ready (in cab switch).

 

I had over complicated it when I first wired it. 

 

These fans are very important. You want em to work, when they need to work. 

 

I also installed a warning buzzer and light. completely separate from the fans. Goes off when top hose is at 220.  

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I use the Spal controller to control only the 2nd fan and left the original OEM aux fan controls as is. I have the controller set up to turn the 2nd fan on at ~175 at LO speed, then turn on at HI speed at ~200. This is how it runs for about 75% of the year, with 25% of that time the fan running at LO speed during the colder months. During the summer around town the aux fan occasionally kicks in at ~220 and that covers the rest of the year. If stuck in heavy traffic @ 100 degree ambient, I can kick on the aux fan with an override  dash switch I wired in if needed. Have had to do this only a few times. And of course the aux fan kicks on whenever I turn on the A/C. It works quite well especially since adding the restrictor disk in the upper hose.

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I put 2 factory AC fans on my Master Jeep. I spent time making wiring control all fancy. 3 Thermo sensors, Relays, in cab switch. Set them up, to where one kicks on at ~180, 2nd kicks on at ~200. Turing on AC kicks them both on. Manual cab switch turns them both on.

 

What I have learned.

 

Best to wire one to always run when engine is on. Wire 2nd one to simple 180 sensor. Have backup switch ready (in cab switch).

 

I had over complicated it when I first wired it.

 

These fans are very important. You want em to work, when they need to work.

 

I also installed a warning buzzer and light. completely separate from the fans. Goes off when top hose is at 220.

That's really good information, I think I will go a similar route, have one wired through ignition, and the other on a temp switch, with Manual switches in the cab to turn them off or on as required.

 

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Take care when mounting your new OEM fans. Their shrouds have to be as close as possible to the radiator (no more than 1/4") w/o touching the fins to pull max air. A lot of guys mount up aftermarket fans with no shrouds and/or mount them too far away from the radiator fins, then wonder why they can't stay cool and start badmouthing electric fan cooling. THIS setup has worked well for me for many years.

I did read your writeup a few months ago, that's what got me figuring on doing this mod. Thanks for the help.

 

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