depends on the current draw of the fan and what gage of wire you plan to use, the fuse needs to be at rated higher than the current draw of the fan (example, you hvae a 40 amp fan draw, you need a 50 amp fuse)

as for using the existing wiring you would use the already there e-fan wires on the signal pins of the new relay, and would run +12v to one of the load pins, and the other load pin would go to the new fan, then ground the fan to the most convient ground (the frame usually), if you want a wire diagram i can make a basic one for you if you provide me the pinout that comes with the relay you want to use.

 

I used a 70amp fuse with 10gauge wire

 

I'm using this relay that Matt suggested with the Taurus fan. http://www.dakotadigital.com/pdf/rly.pdf
I think I'm getting a handle on what is going to be run but if it wouldn't be too much trouble to sketch a diagram, I'd appreciate it. I'm just a little foggy on which pin in the PDC I'm going to be using. The existing relay comes out, correct? Then I run a wire to the pin that is currently telling the existing relay to switch when the AC comes on to the new relay, and the rest sounds straight forward.

In this scenario, the e-fan will come on when the AC is on, which for me is always. The last question I would have is, should I wire the high speed fan wire, or the low speed. I'm leaning to the high, since that is the intention when the AC is on.

 

could someone do a step by step write up?

 

http://durangoclub.com/forum/viewtopic.php?t=10961

 

here ya go, no need to touch anything in the PDC, with your understanding of electrical its best to keep it simple because explaining it all through text is not so easy

 

Ahh, so I use the wires that used to power the old fan to trigger the relay which will then power the new fan. Then It operates exactly how it did before. Perfect. Thanks for laying that out Shooter. The trouble I've been having with this is my application here is slightly different than most of the well documented jobs here in that I had a stock fan while most didn't. I knew there must be a simpler way to power the new fan and you nailed it. Thanks !

 

exactly. that's what I was trying to say, but a picture does a much better job

 

I've understood what you were suggesting, but absent a picture, I've been picturing using the top side of the circuit rather than the bottom side, if that makes sense. All the help has been outstanding and I hope to have this installed as soon as my relay arrives.

Matt- Are you still using the plastic mounting straps? How are they holding up?

 

there still holding up fine. I'm still planning on fabbing up some good brackets for it, but haven't had time to yet.