Electric Fan Override

[aglinks]

Hey all,

I have an LS in my Jeep with an ECM controlled electric fan. What is the best way to wire in an override so I can turn the fan on when the AC turns on?

 

[gert]

I wired my fans with a Hayden fan relay that has a wire on it that goes to the ac clutch that turns on the fan when the ac runs


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[gert]

On second thought you can add a second relay to your fan that gets its power from the ac clutch


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[HackFabrication]

You probably need to do some research on the pinouts on the GM ECM.

I know on my Ford 5.0L, the ECM can control the fan if connect to the proper pinouts. It doesn't allow the function to disable the fan, which my Flex-A-Lite controller does. It has an auto, always on, always off functions. It also has the ability to turn on the fan when the AC is activated.

 

[aglinks]

Can I use a 5 pin relay for this? Where the ECU power will be the normally closed circuit and when I flip the switch for AC, the relay switches to the normally open circuit and powers the fan via the switch?

 

[aglinks]

I actually thought through a diagram and think I can accomplish this with two relays in series at the fan. A 5 pin and a 4 pin. See the attached diagram.

 

[mond007]

why not just pop a over ride switch on the dash so you can flik it on when you want ?