Wiring fan, Key on only power under the hood

Is there a spot under the hood that I can get key on power only, so I do not have to run 32 miles of wire to under the dash? I thought I could get it in the fuse box by the battery, but I guess not.

Run a inline fuse to the fusebox underneath the dash. You have your choice of ignition or always hot 2 feet from your switch.

how old is your jeep. Mines a 87. I just put cut and connected the two wires that go in to the fan temp sensor in the radiator right near the elec fan. Fires the fan via stock relay as soon as you turn the key on. (Always leave enough room to reconnect later if you decide to change it back. I never have ...)

I was hoping there was a spot under the hood that I can tap into. But now that I think of it I think I might put a switch in. There was thread about that some where I did a serch but came up empty handed. By the way it is a 2000.

Sean, I just completed an aux fan switch set up. Mine will run normally, when the switch is on, and when the ignition switch is off.

I went to the local parts house and bought two round switches with LED indicators (one red and one green). All it took to install the switches in the shifter bezel was a 15/16" hole saw. I wired one switch to a battery hot terminal and one to an ignition hot terminal in the fuse block. I use their output to trigger one of two relays that then power a relay near the fan fed directly from the battery. I also cut the factory fan power wire (a whopping 22-gauge beast) and use it to trigger a relay fed from the same battery direct feed wire as the driver selectable switch fed relay.

My fan is now powered by 12 Ga wire direct from the battery whether I turn it on or the computer does. I hope that bigger wiring means more power and thus more fan RPM's and increased air flow.

In the future I would like to install a timer on the battery hot switch (like the rear window defrost has on it) so that I can hit it as I exit the Jeep. The fan (in combination with the hood vents) could then help cool things down for a time then shut itself off automatically. I will be researching this mod after Moab.

Bones :skull1:

I tapped Aux power for my addons by running it thru a relay that is triggered by the lighter being powered ("Hot in Run only.") This is on Renix models - 87-90. Checking for later models is simple - see if you can use the lighter with the key off.

For the aux cooling fan, I simply run a parallel switch from the relay to the panel so I can override it at will - so it is not always on and I can warm up a little quicker on the cooler mornings. Something to consider...

5-90

A 2000 should have two "lighter" sockets. One is for the actual cigar lighter (which was an option) and is powered only when the ignition is on. The other is a power receptacle and is hot at all times. This is the one with the plastic cap over it.

I just did this and I agree it should be an ingnition on source of power. I took it from the nuetral start switch. On the 5speed auto there's a big bundle of wires going down to the switch, 2 of these have switched 12V.

As for being able to turn it on and off manualy, I use a relay module from FLEX-A-LITE. The fan sucked (or didn't suck) but this little electric "BLACK BOX" is great. I now run my aux fan through it. It's got a connectin for AC compressor, temp sensor, manual on, and logic 12V which you can switch off to force the fan off. It's also got a tempetaure control knob so you can set when the fan comes on.

Matt

Ok, after alot of thought, which is hard for me, I have decided to put a temp. sender somewhere in th block to fire the fan. A three way switch and a relay. Manual on, auto on, and off. Where is a good place to tap into the block for a temp. switch? I want to use an additional one, so I can set a lower tem. than the stock fan switch. I think I will just use a switch for now, we leave for Moab TWO weeks from today! arty:

Using that Flex-a-lite module mentioned above, you stick a temp sensor in the upper radiator hose. It's worked out very well so far. You don't need it in the block because the radiator won't do anything till the thermostat opens up anyway.

Matt

I found an adjustible thermostat and relay at Auto Zone today for $15.00. The kit had a probe that goes in to the radiator. I dont care how hot the radiator gets, so I stuck the probe down between the intake and exhaust manifolds. I dont like the way it resoponds there. But the fan will kick on and off by its self. I still think I will try to find a way to put a switch in the block, but I see no extra ports. Do any of you know where I could put a temp switch into the block with out pulling a factory sensor? Again it is a 2000.

I wired the flex a lite 110 to a manual switch and then spliced a power wire into the (+) wires on the factory aux fan. Plugged both fans into a 5 prong relay and now both go on when switched, when the AC goes on, or engine temp reaches 218*. I used the little under-dash light bulb power source for the switch. The money-pit still overheats while towing/going up steep grades in hot weather, but at least I can cool it down within 3 minutes and it doesn't overheat while idling.

Well the $15.00 Auto Zone T-stat was a joke! Quit working on the Kane Creek trail forcing me to turn back.

I am sure my original overheating problem is a computer flaw, the factory fan will not turn on untill the temp gauge is near the red. The fan will blow untill the temp comes down to normal, and then it will turn off. It is like the temp is set to high.

As most of you know, I hate computers, why me?


:badpc: