Electronic Fans Help

I have a 2004 GMC Sierra 5.3 Vortec. It came stock with a mechanical fan. Took that off and put in the electric fans from the 2005+. I want to control the fans with the ECU. I added the wires into the ECU in pin 42 on the blue connector and pin 33 on the green connector. Pin 42 triggers ground for Fan 1 and pin 33 triggers ground for Fan 2. In the VCM scanner software I can trigger these to come on with "Fan Low" for Fan 1 and "Fan High" for Fan 2. In VCM Editor it has on and off temps for each fan and the have been set and the fans are triggered on and off accordingly to what is in Editor.

The issue I am having is the fact that the ECU does not trigger either fan to come on when the A/C is turned on. Is there some other setting that I have to change in order for the ECU to trigger the fans to come on with the A/C.

Also, I want the fans to turn off after a certain mph. In Editor it has values that I can change but the ECU does not turn the fans off according to any of the speed values. There is a not in Editor that says "First Stage Fan Disable Speed: If AC is on, fan wil disable above this speed. If fan is on, it will disable above this speed if coolant is hot (V6 only)." Is this function really only available for V6?

So... Can I have the ECU trigger the fans when the A/C comes on and can I have the ECU disable the fans based on speed for the V8??? Any help on this would be greatly appreciated.

Look at a stock 2005 GM pickup (with stock e-fans) for some real good ideas on how to set up your electric fans. All paremeter questions should be answered there. If you need help, shoot me a note.

I don't have a stock 2005 GM pickup accessible. Any other suggestions?

Is there one in the repository ?

can some just input what would be the best "settings" for the efan swap. like what temp to be on ect. get hot in arizona

A lot depends on your operating system inside the PCM, what PCM you have and how much of the donor vehicle AC wiring makes the trip into the swapped vehicle. You can't just put in a few E-fan "on" and "off" temperatures and make it work.

I run Four Seasons part number 35879 adjustable fan relay kits and don't depend on the PCM for any of this. This also kicks on one fan when I turn the AC on to immediately control excessive compressor head pressures. I run two of these fan relays - one for each of my two E-fans for complete fan independence and dependability. Each fan has its own power, ground, fuse, adjustable thermostat and relay for best reliability.

https://www.carid.com/four-seasons/r...kaAqxEEALw_wcB

There is also another vendor below if you want adjustability on a digital screen for more money:

https://daviescraig.com.au/product/d...h-12v-24v-0444

Rick

MrForce,
I am having a similar issue. I have gotten the MPH shutdown working and I am running my fans (Both) on low today by lowering the stage1 "Enable AC Press" setting to below what my AC pressure switch is reading when the AC goes on. (the voltage the AC pressure switch is reading should be multiplied by 100 to give you the pressure, roughly.) The fans will shut off above the shutoff speed setting. But I am not getting fan2 on when I turn the AC on as I should.

Not sure the cause here, but it is not just you.