dual electric fans wiring

[70hemicuda]

I wanted to have them on a switch and also work like factory together. So far I have the one stick wired and the other is on its own relay. I tapped into a blue and pink wire that goes to the stock relay. But my problem is that both fans go on as soon as the engine starts and they stay on all the time. I just want both to work like the factory one for now. The switch will come later. All I need to know is what wire controls the stock fan and tells it to come on with ac or at 218. I cant for the life of me find the right wire

 

[Demonoid369]

I wanted to have them on a switch and also work like factory together. So far I have the one stick wired and the other is on its own relay. I tapped into a blue and pink wire that goes to the stock relay. But my problem is that both fans go on as soon as the engine starts and they stay on all the time. I just want both to work like the factory one for now. The switch will come later. All I need to know is what wire controls the stock fan and tells it to come on with ac or at 218. I cant for the life of me find the right wire

Well the knowledgable guys here and on cherokeeforum both said to keep the mech. fan so I guess we'll see you in a few months posting up wondering why you're over heating or why you blew a head gasket.

 

[rmz45099]

It's the blue and pink wire. Or if you don't want to deal with the cluster of wires to the ecu you can just tee off the stock efan. It's doing the same thing. You just need to tell the new relay when to turn on. Your using that signal wire as a "switch" just as you would with a regular toggle switch.
If you use the blue and pink and have the new relay wired like I posted above then that could be the problem as the blue and pink wire is a ground. The computer doesn't switch power on and off to the fan, it grounds it. So it's a little different when wiring it in.
If you use the wire from the stock fan like I said. It will work the way you want it to.

 

[70hemicuda]

I finally got it guys. Turns out my splice didn't peirce the wire on the stock fan positive. But I got it and now it works like a charm. I'll post up in a month or two to let you know if I blew my head gasket or not. Thanks for the help everyone

 

[rmz45099]

why not just splice the relay signal from the ECU and control a second relay? Or replace the existing relay with a higher rated relay and increase the wire size from the relay to the fans? Lots of ways to do it, I don't think just simply splicing into the positive wire at the fan is the right choice though, you need to account for double the current in the wires and through the relay

wait, if you want to have direct control over the fans why didn't you say that? If you want full control, just run a switch inside wired to the relay ground. If you want partial control, cut the ground to the stock relay and run that through a switch so you can have the computer control the fan all the time except when you switch it off. Same wires could be used to control the second relay ground for the second fan before running to the switch.

Using the wire from the stock efan to trigger a new relay will put almost zero new load on that circuit. A relay takes very little amps(milliamps actually) to switch. It's drawing power from the battery. That is the whole point of using a relay, to create a new separate circuit because the stock one is only designed to handle one fan.
The wire from the stock efan or from the PCM is accomplishing the same thing, just acting in as a switch.

 

[rmz45099]

I finally got it guys. Turns out my splice didn't peirce the wire on the stock fan positive. But I got it and now it works like a charm. I'll post up in a month or two to let you know if I blew my head gasket or not. Thanks for the help everyone

Did you piggyback a new relay in or did you just go straight to the new fan? If you didn't use a new relay you will probably have problems.

 

[70hemicuda]

Used a new relay. So it's one relay per fan

 

[Hoooper]

Using the wire from the stock efan to trigger a new relay will put almost zero new load on that circuit. A relay takes very little amps(milliamps actually) to switch. It's drawing power from the battery. That is the whole point of using a relay, to create a new separate circuit because the stock one is only designed to handle one fan.
The wire from the stock efan or from the PCM is accomplishing the same thing, just acting in as a switch.

This is why I said positive wire at the fan first, not just positive wire for the relay. So that somebody wouldnt get confused and think I just meant positive for the relay.

 

[jeeperjohn]

If your goal is good cooling, go back to the stock setup.