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Old 07-09-2020, 03:50 PM   #1
ChuckLee
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Almost caught her on fire! Need help with fan diagram

Well, she nearly caught fire. mark8 fan (i think its a mark8 fan) melted the hi speed positive wire in the ford pigtail at the fan. Known issue there I've learned, need to put bigger wires to the fan. Popped my 50a fuse, which started a chain of unfortunate events haha.

On to what I need help on.
I want to also rewire my fan configuration completely. I was using a flex-a-lite fan controller but i want to get back to PCM controlled fans and ac.
I'm running a blue/green p59 PCM but i would like to run my fan and ac like a 99 camaro.
Can you guys please help me with a specific wiring diagram for this application?
1) My AC request and relay setup is just like a 411 pcm on a 99 camaro. I just need to run pin 33 hi speed turn on somewhere to tell fan to go hi speed when ac is on.
2) 2-speed fan

Any of your help would be greatly appreciated.
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Old 07-10-2020, 04:22 PM   #2
TrybalRage
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Re: Almost caught her on fire! Need help with fan diagram

Is it a single two speed fan?

http://lt1swap.com/wiringharness.htm

If you scroll down there's an image showing the wiring through two relays.
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Old 07-10-2020, 07:56 PM   #3
ChuckLee
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Re: Almost caught her on fire! Need help with fan diagram

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Originally Posted by TrybalRage View Post
Is it a single two speed fan?

http://lt1swap.com/wiringharness.htm

If you scroll down there's an image showing the wiring through two relays.
It's a dual speed fan.....i think i'll only use high speed though. have 320a alternator so that's not an issue, gonna run 80a relays.
I guess it would be nice to see a diagram for each option, one diagram showing how i would do single speed only with AC trigger and one with 2-speed with ac trigger.

I looked at that diagram....i'm not running dual fans.....just one single fan with 2 speeds. (if i choose to even use two speeds which i won't)
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Old 07-10-2020, 08:37 PM   #4
AussieinNC
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Re: Almost caught her on fire! Need help with fan diagram

How much amperage do these fans need?

Make sure you use adequate wire size to carry 80 amps...

3 gauge is the recommended wire size for household 80 amp breakers....

Keep the wire runs as short as possible.

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Old 07-10-2020, 10:41 PM   #5
ChuckLee
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Re: Almost caught her on fire! Need help with fan diagram

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Originally Posted by AussieinNC View Post
How much amperage do these fans need?

Make sure you use adequate wire size to carry 80 amps...

3 gauge is the recommended wire size for household 80 amp breakers....

Keep the wire runs as short as possible.

Thanks, runs will be about 7ft.
Mark viii fan on high speed from a dig will hit 60-65amps initial and lower down quickly to 30-35 continuous. I’ll be using 8guage.
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Old 07-11-2020, 01:53 AM   #6
clinebarger
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Re: Almost caught her on fire! Need help with fan diagram

Those big single Ford fans are not meant to start at full speed, They're suppose to be started gradually via a PWM control.

It's best to run a P59 with a Hi/Lo arrangement with 2 fans & 3 relays.
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Old 07-11-2020, 08:42 AM   #7
ChuckLee
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Re: Almost caught her on fire! Need help with fan diagram

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Originally Posted by clinebarger View Post
Those big single Ford fans are not meant to start at full speed, They're suppose to be started gradually via a PWM control.

It's best to run a P59 with a Hi/Lo arrangement with 2 fans & 3 relays.
I agree. the current controller i have is set up that way (it has soft start then full boogie). the only PWM control that's any good is the Auto Cool brand and I might end up just buying that. the PCM would work for me but even that doesn't have pwm control or soft start for high speed use. That isn't a big deal since the low speed fan will already be running fan when the hi speed is requested, however AC turn on which i use a lot will require full boogie from a dig whenever i hit ac button. i've rewired my fan with bigger wires recently too, which is very necessary on these fans or else they will melt.
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Old 07-12-2020, 10:07 AM   #8
Steve Cole
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Re: Almost caught her on fire! Need help with fan diagram

Check out the PWM controller from Derale.
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Old 07-13-2020, 09:56 AM   #9
Rich84
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Re: Almost caught her on fire! Need help with fan diagram

The Ford fans on low are extremely powerful. I ran a taures fan for years with only low speed and you could watch the temperature gauge fall instantly when it kicked on. I would only use high with the Ac on.
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Old 07-22-2020, 11:28 AM   #10
verdell
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Re: Almost caught her on fire! Need help with fan diagram

I'm running the single 2-speed fan as well with AC and an 80 amp relay and have been going on 2 years now. I'd really like to see a wiring diagram to run both speeds as required myself. I even picked up Volvo relay set up from the junkyard.
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