There are lots of videos and resouces out on the interwebs about this, but I wanted to do a quick write up about it since it may be more helpful than a video. I am sharing what I did with my setup and how I did it so to each is own and your miles may vary but this is pretty much the same with aftermarket fans. This is just ging to cover the Fan setup without AC. Depenging on the PCM you will have more parameters to adjust for the AC settings with electric fans. I have a P01 PCM so there are not as many parameters to change and currently im not running AC.

Also a video about it where I go over it can be found here. I am not expert though...just a guy learning stuff as I work on my own LS build.


Hard Parts:

1. Dual Electric fans from a 2000's Escalade or Denali from a junk yard and the fan relay fuse box that is attached to the engine compartment fuse box. Pic of what the fuse box looks like is below.

Get the entire fuse box, harness and the fans as you will use the green and blue wire from the fan fuse/relay box harness for the ground wires to go the the PCM for controlling the fans

Setting it Up:

1. Mount your electric fans and hook up your harnes and route it so that you can attach the fan fuse/relay to the right side of the engine fuse box. There will be a provision on the engine fuse box that it will slide in place.
2. On your PCM there will be two pins that you will be focusing on to wire up the trigger wires for Fan 1 and Fan 2. The Green Wire for Fan 2 will go to Pin 33 on the Blue Connector and the Blue Wire for Fan 1 will go to Pin 42 for the Red Connector
3. You can run the wires directly to the PCM connector since the entire circuit is already fused from the fan fuse/relay box and these are ground control side wires.
4. You can go to LT1swap.com and find the wiring diagrams there to help you further if you want.

Electric Fan Fuse/Relay box and harness






Programming:

I use PCM Patcher and TunerPro so if you are using HP Tuners the settings will be similar. This example I am using PCM Patcher.

1. After you connect to your PCM and download the BIN file using PCM Hammer and open it in PCM Patcher search for "recirculate" or "recirc" in the search bar or just find the Vehicle System folder
2. Within the folder you will see the parameter for Auto Recirculation or Recirculation Door. This will be checked by default so that the PCM controls the recirculation door automatically but when you uncheck it the PCM uses it for Fan 2 control.
3. After you save the changes made to the recirculation door parameter go to the Fans folder within the Vehicle Systems section.
4. You can select the the Fans folder and it will show all the parameters associated with Fan 1 and Fan 2 control.
5. You can mirror the parameters I have in the screenshot as a starting point. I have my Fan 1 come on at 185 degrees since during the summer in the south it gets really hot here and I want to ensure the engine stays below 190 degrees.
6. For the Fan 1 and Fan 2 low and high thresholds be mindful to only have about 5 degree difference for the fan 1 low and high and the Fan 2 low and high.
7. Ensure that you have the Fan type parameter set to series parallel for dual fans
8. Remember to set your vehicle speed low and high correctly as well. You want to ensure that you set your fans to turn off at higher speed as they will not be needed due to ram air flowign though the radiator.
9. once you save your parameters save the Bin file as something that helps you know it has the Fan changes and write it to the PCM with PCM Hammer.
10. Start up the vehicle and let it get to the operating temp for Fan 1 to turn on and once it does your good to go!

Auto Recirculation Parameter:



Fan Control Paramters:

 

Since you are talking E-Fan conversion and it is pretty generic information.

Early truck OS often do not have the full fan code in them. I usually use a 2002 OS for all conversions. The 2002+ code allows for the ac pressure transducer to be enabled to properly control dual speed fans when using AC.

I have run into vehicles that ram air alone even at 70-75 mph will not keep them cool. In most cases enabling the fans to run cools them down to an acceptible temperature but not always. I had one that I had to go back to the clutch fan on to keep it cool prior to making changes to the cooling stack by adding factory GM air guides and improvising an extension under the factory air dam (more on that below). Since it was P59 run I went back with an EV clutch that is PCM controlled. That was the best of both worlds. You could control the mechanical fan to mimize power loss yet still have full cooling capacity on demand. The P59 fan code for the EV clutch has tables to control the fan for engine temp, transmission temp and ac pressure.

On my Express van I ended up adding the air guides GM put on the newer vans that bolt to the condenser and help funnel all the airflow from the grille opening through the cooling stack. That helped the cooling considerably vs allowing a lot of that air to flow around the cooling stack through the core support openings behind the headlights. Adding a 3" tall strip of PVC patio/sidwalk edging below the factory air dam also considerably improved the cooling by helping create more negative pressure under the van to help draw airflow through the cooling stack. The result of those changes is I went from almost always needing a powerful fan functioning to rarely needing a fan at all over ~50 mph.

 

Nice additional info to add to it! Each use case will be different but the more info to share the better!