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Need hot wire for dual Spal fans

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Dearl

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Discussion starter · #1 ·
I have installed a PRC radiator with dual Spal fans in my 55 Sedan. My battery is mounted in the trunk and I have a heavy gauge (Moroso brand) positive wire going along the frame to my mini starter that's on my big block.
I need a hot wire for my dual Spal fans. I will be using relays and a temp sensor to turn them on an off.
Can I get my hot source off the back of my 100 amp Powermaster alternator or should I run a wire around to the starter? My wiring harness is a stock type from Danchuk that was already upgraded for an alternator.
The harness was bought new in 2001 and and is still good, has only two years of use on it when I had a smallblock.
Also what gauge wire should I use?
 
#2 ·
Dearl said:
I have installed a PRC radiator with dual Spal fans in my 55 Sedan. My battery is mounted in the trunk and I have a heavy gauge (Moroso brand) positive wire going along the frame to my mini starter that's on my big block.
I need a hot wire for my dual Spal fans. I will be using relays and a temp sensor to turn them on an off.
Can I get my hot source off the back of my 100 amp Powermaster alternator or should I run a wire around to the starter? My wiring harness is a stock type from Danchuk that was already upgraded for an alternator.
The harness was bought new in 2001 and and is still good, has only two years of use on it when I had a smallblock.
Also what gauge wire should I use?
Click to expand...
How many amps do your fans pull? The 12V power wire for your fans should be fused. You'll also have a small 12V wire going to your relay.
 
#3 ·
I ran a hot wire off the alternator as you've suggested. works perfectly fine. It's been a while but I believe a 10ga wire I ran. I can check on this tomorrow and get back to you. good luck
 
#4 · (Edited)
10 ga wire is good. Yes it needs to be fused and mount the fuse close as close to the source as possible.
Back of the alternator or at the starter work equally well.

Consider an MIDI/AMI or ANL type fuse and holder. ATO, glass tube or even Maxi fuses are not a good idea for this. You will want a 40A fuse and ATO and glass fuses don't go that high. Maxi fuses do but the holders for them are rarely rated for that high.

I get my MIDI/AMI holders and fuses at waytekwire.com.

https://www.waytekwire.com/item/46390/Cooper-Bussmann-LMI1-E-2-0-MIDI-Fuse-Holder/

or this:

https://www.waytekwire.com/item/46312/Littelfuse-04980921GXM5-Inline-MIDI-Fuse-Holder/
 
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#5 ·
roger1 said:
10 ga wire is good. Yes it needs to be fused and mount the fuse close as close to the source as possible.
Back of the alternator or at the starter work equally well.

Consider an MIDI/AMI or ANL type fuse and holder. ATO, glass tube or even Maxi fuses are not a good idea for this. You will want a 40A fuse and ATO and glass fuses don't go that high. Maxi fuses do but the holders for them are rarely rated for that high.

I get my MIDI/AMI holders and fuses at waytekwire.com.

https://www.waytekwire.com/item/46390/Cooper-Bussmann-LMI1-E-2-0-MIDI-Fuse-Holder/

or this:

https://www.waytekwire.com/item/46312/Littelfuse-04980921GXM5-Inline-MIDI-Fuse-Holder/
Click to expand...
Roger also has a nice diagram if you want to run 3 relays and run your fans on low and high speed. I have the same PRC setup and Roger helped me a lot and it works great. Also, works with a trinary switch.
 
Discussion starter · #7 · (Edited)
Thanks for all the replies. For now I have the power source going to the back of the alternator with two simple toggle switches. It is just temporary so I can start it and move it around in the yard.
I did drive it out on the hard road to see if my tranny shifted correctly.
This morning I found in a box the AAW dual electric fan relay kit part #510001 that came with my PRC radiator. I'm going to use it but the schematic doesn't show a two speed fan setup.
I been talking with Roger1 to find out if I can adapt a Dakota controller to this relay kit as I really want to have the fans set to come on at half speed then full speed.
I will also be adding a Southern Rods A/C that I have later on. For now I just need the fans to be set up and operate correctly so I can attend the Turkey Rod Run at the end of the month.
 
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