Relay/Switch for fan

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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=79292
Printed Date: June 21, 2025 at 2:50 PM

Topic: Relay/Switch for fan

Posted By: illicon2003
Subject: Relay/Switch for fan
Date Posted: June 18, 2006 at 6:55 PM

Ok, I have a 4 prong relay and I'm trying to wire it to a switch to power a fan. The switch has 3 prongs, Power, ground, accessory. I was thinking about using the switch inline with the 12v+ for the relay itself(to toggle the power on and off). But I do not know how to do that on the switch. Please help me. Also, I'm completely bypassing all of the OEM wiring, and I'm running a power wire off the alternator with a 30amp inline fuse, which will be going to the relay.

Replies:

Posted By: djfearny2
Date Posted: June 19, 2006 at 1:41 PM

all you need is a little switch./

hook up like this

relay

pin 85 negative input from switch
pin 87 and pin 86 12 volts constant fused from battery ok
pin 30 output to fan
pin 87a not used. you probably need to get a better relay than that 4 pole as it maybe missing a pole needed in setup i have described.

ground second wire from switch

this setup will not work on a switch with a build in light it will only work with a two pole not light switch.

if you go to jegs.com they sell a fan controller that turns on fans via temperature which you set via a knob. that with a 12 volt relay will control your fans automatically at a set temp of your choice.

copy and paste link to know what i am talking about

https://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=21529

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Jon
Installer/Help Technician
---coral springs florida---
mecp certification is not always needed. I have it and it has not helped me out at all. my experience out shines it.

Posted By: hotwaterwizard
Date Posted: July 15, 2006 at 10:49 AM

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: hotwaterwizard
Date Posted: July 15, 2006 at 11:02 AM

Oh yea forgot the ground on the switch.

posted_image

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !