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Old 02-03-2014, 10:23 PM   #1
Jfarns03
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LS swap cooling fans

Hey guys I did the 5.3l swap on my 68' and I need help hooking up my single radiator Derale fan. It has a black wire and a blue wire. I understand that the black is for the ground, hook to chassis, engine etc.. but what gets me is that with the modified harness Wait4me stripped down, they label two wire looms. #1 cooling fan (hook to relay,outputs negative signal) {green wire}
#2 cooling fan (hook to relay,outputs negative signal) {blue wire}

I spliced into the #1 wire loom and connected both cut ends of the green wire with the blue wire off the fan. By no means am I good with electrical** what have I done wrong and what do i need to do to fix it? Thank you buds
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Old 02-03-2014, 10:46 PM   #2
dwcsr
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Re: LS swap cooling fans

You need to connect a relay in there. You can't connect direct from the PCM to the fan.

The blue fan wire needs to be connected to a relay #87 terminal. The 30 term to the battery. The 86 tem to the green PCM wire the for engine cooling. You would use the PCM blue wire if you had a second fan or a 2 speed fan.
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Old 02-03-2014, 10:50 PM   #3
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Re: LS swap cooling fans

I dont understand what you mean by 87 terminal and 30 terminal? explain please?
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Old 02-03-2014, 11:03 PM   #4
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Re: LS swap cooling fans

Nevermind! I googled what the 87-30 terminal was. I understand that now. Blue to 87, 30 to battery, then 87 term to the green wire. Since the green wire is cut into two parts i just combine the three wires together? Thanks!!
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Old 02-03-2014, 11:09 PM   #5
dwcsr
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Re: LS swap cooling fans

I think you should purchase a fan relay it will make your install much easier. They come with instructions so you can just connect it and not worry about terminal numbers.

But as far as the terminal numbers go on a relay each terminal is numbered according to function.
For a 12V NC relay (Normally Closed)
#30 power in
#87 power out > this will be closed and will open when the 86 is powered
#87a power out. > This will be open and will close when the 86 is powered
#86 12v actuator power
#85 ground

We have several relay kits available at
http://www.hollisterroad.com/proddet...=C4060SXL5MTFK

This will run a single speed single fan.
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Old 02-05-2014, 12:01 AM   #6
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Re: LS swap cooling fans

How much CFM is that Derale fan? Do you plan on running AC? If so, does that fan kit include a trinary switch? If not, it might be something to think about adding. It basically works in parallel with your PCM output to allow the fan to turn on if the high side pressure of the liquid line exceeds roughly 250 psi. That is if you don't plan on using the pcm controls for the stock AC system.
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Old 02-06-2014, 06:54 PM   #7
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Re: LS swap cooling fans

Quote:
Originally Posted by dwcsr View Post
But as far as the terminal numbers go on a relay each terminal is numbered according to function.
For a 12V NC relay (Normally Closed)
#30 power in
#87 power out > this will be closed and will open when the 86 is powered
#87a power out. > This will be open and will close when the 86 is powered

#86 12v actuator power
#85 ground
You have the N.O. and the N.C. connections reversed. #87 is N.O. and closes when coil is energized, and #87A is N.C.
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Old 02-06-2014, 10:56 PM   #8
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Re: LS swap cooling fans

There are a lot of ways to use relays.....just remember there are two types of relays when it comes to 5-pin styles. You have SPST and SPDT. The difference is you could have two #87 terminals SPST and one 87 and an 87a which is SPDT. What this means is 87a and 30 are latched until 86 is powered if 85 is ground. Dual 87 terminals just means you have two circuits powered simultaneously. For voltage carrying you have options but for ground triggering you have a lot more-this is the basis behind most power door lock kits and even power window systems. Relays can carry a voltage signal or complete a ground path.
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Old 02-06-2014, 11:19 PM   #9
dwcsr
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Re: LS swap cooling fans

Quote:
Originally Posted by 67 Burb View Post
You have the N.O. and the N.C. connections reversed. #87 is N.O. and closes when coil is energized, and #87A is N.C.
You are correct for what I described.

85 = relay coil -
86 = relay coil +
87 = common contact
87a = normally closed contact

Last edited by dwcsr; 02-06-2014 at 11:34 PM.
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