3 Relay Automotive Cooling Fan Logic

[@bhwjrproductions]

I’ve had this 3 fan relay setup on my car for a couple of years, it’s been on the road full time for the last few months and it’s working great. The wiring diagram I used I found online. My LS computer controls the fans and I have a manual over ride switch that I never finished connecting because the computer controls seems to be perfect. I still have to figure out how to get the AC to trigger the fans.

[@RustyWrenches]

I also thought about adding a manual override as well. Maybe someday. I'm really hoping the pressure switch will work with my setup so the ECM will control the fans for the ac. We will find out soon! Thanks for watching!

[@TheTruthBeToId]

Dude my head was fuming on trying to make this work like thing. THANK YOU for having my solution before my head exploded.

[@RustyWrenches]

You bet. It still bends my mind a little.

[@tuanas458]

87a is for use like(for example) day time running lights which are automatically on when you turn on your car. And obviously it turns off(of become low powered) once you switch to the main headbeams. You can leave 87a open and not hooked up to anything.

[@RustyWrenches]

In this case it's needs on the 3rd relay to allow a current path through both fans in series.

[@ibanez741852]

The fatal flaw shouldn't be a concern. If you have 12v on both sides of the fan it's an open circuit so current won't flow. There is no ground. If you touch 2 wires to positive and touch them together on the other end, nothing happens. Electricity is trying to take the shortest path to ground. Now if that first relay was shorted to criund before 30 and the second relay was not functioning it would turn the fan backwards but what are the odds lol Great video though!

[@RustyWrenches]

Fair point. Thanks for watching!

[@samisulaiman7967]

I have a Suburban 2012 and I want to make both of the fan run on high speed all time and I have 4 relays with 5 pins can you show me the diagram thanks in advance

[@RustyWrenches]

That’s a good question. I don’t have an answer on that. You might try calling Current Performance. I know they do a lot with tan wiring.

[@stevemullin7472]

85 is ground on any relay I've ever seen?

[@RustyWrenches]

I agree. GM calls out pin 85 as positive and 86 as the negative trigger in its wiring diagram so I stuck with it.

[@frankm8533]

Seems right Lol. I was never to good with wiring or circuit stuff I just never learned it right

[@RustyWrenches]

Thanks. It takes me a good bit of staring at it to quasi-understand it. It makes just enough sense to get myself in trouble 😀

[@VideosByAl]

Interesting solution to noisy fans.

[@RustyWrenches]

It really is. I can't take credit for it, but it sure is going to be nice!