Electric fan wiring

Blue85

Member

Dec 25, 2020

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Florida

Dec 28, 2023

#1

• Dec 28, 2023

• #1

wiring in my contour fans. I have 2 relay and I am running a fi-tech injection. Basically the ecm turns on the relay by applying a ground to the relay. Pretty simple. However I need 1 of the fans to turn on with the ac which is triggered by a positive signal. So do I need to add another relay?

 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Admin Dude

Jan 4, 1985

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Dec 29, 2023

#2

• Dec 29, 2023

• #2

Assuming you're running your two relays from an ignition source and the ECU for ground, the easiest thing to do would be to bypass one of the relays with a third so, yes. You would use the third relay as an A/C switched ECU ground [clone].

 

KRUISR

10 Year Member

Apr 16, 2015

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Dec 30, 2023

#3

• Dec 30, 2023

• #3

So if I understand your set up correct, you have two relays, one for each fan. Your ECU grounds both relays to trigger both fans. What size are the relays?

Do you run the fans on high speed only or do you use the thermoresistor in the fan shroud for low speed?

 

Kid wita 5oh

I'm definitely not in the original hole

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Nov 5, 2000

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Jan 2, 2024

#4

• Jan 2, 2024

• #4

I run 2 70a relays. One for high, one for low(using the factory low speed resistor), ground triggered by temp switch....and then a standard 30a relay as a high speed change over relay for the ac trigger(positive ac signal triggers the relay to provide ground to the high speed relay)