Re: Cooling Fan relay setup
 

You may want to talk to the guy that runs LT1swap.com. He is incredibly knowledgeable about this, and he knows which pcm will do what you are asking. His website is a mess, bit all the info is there.

Re: Cooling Fan relay setup
 

Thank You I will check it out. I am going with the 3 relay setup. Steve

Re: Cooling Fan relay setup
 

I think the best option without putting some janky resistors that sole purpose is to get hot just to acquire a low speed....

I would just install a pusher fan in front of the radiator and wire the 2 fans just like an LS1. You will get both fans on at 1/2 speed for LOW and both will be at full speed for HIGH.

This is the relay box I use when I did fan harness'

Just a quick google search shows this link, the box is good quality, not amazon quality, uses quality seals and terminals.

https://ceautoelectricsupply.com/pro...aterproof-pdc/

clint

Re: Cooling Fan relay setup
 

Thanks for the input on this. Still figuring everything out. Close on a solution. Steve

Re: Cooling Fan relay setup
 

I used the factory 3 relay with wire harness and fans off of an Escalade. Made it super easy. Plug and play.

Re: Cooling Fan relay setup
 

rich, what year escalade did you get the setup off of.

Re: Cooling Fan relay setup
 

I believe it was 05-06..You can kinda see the relays in this photo at the bottom.
I also used the radiator.
Attachment 2325259

Re: Cooling Fan relay setup
 

I used the same 3-relay setup, as Hcb3200, to get two speeds for both fans.
Thanks for posting it.

The OEM Vintage air set up was to run one fan on high or both fans on high.
I wanted to keep the noise to a minimum, so I could hear the "Black Widow -Angry House-wife’s" mufflers. LOL.

How if functions:
When motor is cold and the air is off no fans are running.
Air on "no matter the conditions", both fans on high.
Above 180F both fans run at half speed.
above 190F both fans run on high.
Both these temperatures are ground outputs from the computer. They can be programed differently if needed.

Air-conditioning provisions are supplied by just added the ground from the air Trinary switch to the high-speed relay.
It matters not if the computer is grounding the relay or the Trinary switch grounds the relay. Or even if both are grounded, both fans run on high.
This is important to keep your air-conditioning pressures from going too high.

On can spend $250 on propriety controller boxes or $25 on three relays on Amazon. The down side is the wiring gets out of hand quickly and isn't pretty unless a lot of care is taken. I hid the relays behind the battery between it and the core support. It has worked flawless since day one.

Later year fans are controlled by the ECM/computer and it's a Pulse Width Modulated output that can run the fans at variable speeds.
These require a different setup or dedicated sensors in the radiator.
Cheers

Re: Cooling Fan relay setup
 

Thankl You. That is exactly how I am doing my setup. 3 relays but only one fan. I am going to try a 200 watt 2ohm resistor as a substitute for fan one. Steve

Re: Cooling Fan relay setup
 

Your resister will draw 16.6A. Should be close to the fan draw when running.
It will work fine.

Re: Cooling Fan relay setup
 

Thank You. I was hoping that would be the case. Steve