Triple Threat Fan Install, Where's the closest ignition switched wire by the battery?

I'm in the middle of installing my triple threat fan setup - one of the last things I need to do before I can fire up my engine rebuild. I'm going to check the FSM tonight when I get off work, but I had a couple of wiring questions to help the install along.

On a 98 4.0L / AW4 / NP231 Cherokee... :repair:

1) Where's the most convenient ignition switched wire close to the battery that I can tap into?

2) What color/location wire am I looking for that controls the AC clutch?

Thanks guys in advance for any help you can offer!

Jonathan

Still in the middle of working on this...

No one has any help to offer? I'm about to run a wire off the radio or ignition switch, even though my relay is located right next to the underhood fuse box.

I don't know the specific colors or much about electronics, but why not choose something going to the relay box? Like the fuel pump? Locate it in the loom and tap it?

You can get fuses that have a wire coming off of them and replace the fuel pump relay fuse with one and use the wire to activate a relay for your fan controller.

what jeeperjohn said is probably the best idea. I pulled the fan relay and put a spade connector into the power terminal of the realy socket, but that causes a check engine light.

the ac clutch wire is the only wire that goes to the compressor, it connects into the side of the compressor.

inside the harness that runs to the PDC is a dark blue, 12 ga wire. Its the ignition one wire, hot in start and run.

Thanks for the replies guys! I ended up going my own route and got this all buttoned up Saturday. I ended up building a small bracket that sits right next to the underhood fuse/relay box. It's worked out nice with all of my relays and fuses right next to the OE spot.

---Orange wire is supposed to go to 2 of the 3 fans and run when the temperature sensor tells it turn on. I wired to all 3 fans because my AC currently doesn't work.

---Blue wire is supposed to go to 1 of the 3 fans and run with the AC on. I installed the wiring for this, its extended with a spade connector toward the third fan. So when I get the AC fixed, I can simply disconnect the one of the fans from the orange wire, and attach it to the blue.

---Yellow wire is supposed to go to an ignition switched power source. Without pulling the PDC loom apart, I found a 12 volt switched wire going to the blower motor. This should be OK because...

---Red wire goes directly to the battery positive.

---Black wire goes to the ground behind the battery (pre-existing ground connection).

Update: I'm using the single row CSF radiator from Dirk at DPG (plastic side tanks). I've got the 3 fans hooked up to run at the same time and the thermostat (adjusted the pot) to come on below 210*. So far it gets up to 210 idling in traffic here in NC but doesn't go above. I've only out ~200 miles on this setup with the rebuilt engine. I also need to replace the relay with one around 75 amps. I also think I have an exhaust leak at the donut where the manifold meets the downpipe, but again it still stays at or below 210.

But so far so good.

Update: The downside to wiring the fans this way, is once the engine is warm the fans will automatically fire up when I switch the ignition so I can use the windows or radio without turning the engine on. The fans draw quite a bit of current so I would imagine it could drain the battery quickly, sitting with the key in but the engine off. This could be especially problematic in the middle of winter.

I'd like to add a switch to override the thermostat control so I can manually turn it on/off. The dangerous thing with doing this is forgetting to turn the switch on, and then letting my wife borrow the Jeep.

ALL else is still great though. I've noticed heat creep after parking with the engine hot, but after I fire the engine up and start driving the temp returns to normal within minutes.

Have you checked how long the fans will run with the engine off? It might not be that long to cause a problem.

Talyn - no I haven't tried it yet. Wife is going to school opposite schedule of my work and didn't want to get stranded without a jump box. You're right though, with a good battery and alternator it may not be an issue. I said before that I think I have an exhaust leak at the donut gasket (header to downpipe) which would keep the fans running longer from heat soak - something extra to think about.

Triple Threat Fan Install, Where's the closest ignition switched wire by the ...

I have been running my fans direct to a battery souce for over two years. I was going to swap it to an ignition souce but i havent had a problem with it yet. Even on the hottest days the fans only stay on for a few minutes after you shut the key off. Just thought i would add my experience to the list. They move some serious air. I kind of like the fact that it pushes all the hot air out of the engine bay after i shut off the motor.

Oh and i have some major cracks in my exhaust header too. Havent noticed any extended run time since those have developed.

GordoSmasho said:

Even on the hottest days the fans only stay on for a few minutes after you shut the key off. Just thought i would add my experience to the list. They move some serious air. I kind of like the fact that it pushes all the hot air out of the engine bay after i shut off the motor.

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That is a feature I would definitely like. Many newer cars are designed like that.