4ws f 7

I am sorry for posting another thread on E fans. But I have installed factory 05 up 1/2 ton E fans, with a Nelson harness. I have read E fan posts for over
a year and it's like calling the DMV you ask 10 people a question and you get
10 different answers. I want E fans to both work at low speed when a/c pressure is over 250 pounds. And both fans to work at high speed if coolant
temp. goes over 212 degrees. When I talked to Nelson he states this is not possible. But I have read posts that say this is possible. If Nelson was just blowing me off because his harness does not support this, I would have liked him to just tell me his harness does not work that way. As the fans at this time are on any time the A/C is on. Even if the truck is stone cold and outside temp. is under 30 degrees. Somewhere I wrote down the factory harness part #. If I get factory harness and EFI live or HP Tuners will I be able to program fans the way I think they should work.

BlewSilverado

iTrader: (3)

I have a factory harness and it works just as you described. The fans only come on when the AC gets to a particular pressure. It does not have a AC trigger wire at all. It is controlled thru the PCM by only two wires a low speed trigger and a high speed trigger. Mine was changed by my tuner so the high kicks in at about 200 degrees low speed is at 185. He also has it set so that it stays on after the engine cuts off for about 15 or 20 seconds on low speed. And there is another setting that I thought was cool where the fans dont run at all at highway speeds if they are not needed.

07 z71 silverado

my fans come on all the time. i think its in the tune. even though it will be 20 degrees outside they will turn on.

bigredexpress99

iTrader: (15)

I did a HUGE write-up about this. Although I built my own harness, it is exactly like the factory one. . . I'm a GM tech, so its gotta look OEM for me. LOL. Anyways, I tune with EFILive, and have set up fans through the PCM exactly like an 05 and up truck.....I'll post the link to my writeup....

bigredexpress99

iTrader: (15)

https://www.performancetrucks.net/fo...2&page=1&pp=10

here ya go.....this is what I did....starts bout page 6

4ws f 7

First I want to thank everyone for the info. But still everyone contradicts each-other to what the PCM can and can't do to run E fans. I think I will get a factory harness as I have factory fans. And spring for EFI live. And than try to set both fans to run at low speed with a/c high pressure over 200 pounds, both fans high speed over 300 pounds, both fans low speed with coolant temp. over 200 degrees, and both fans high speed with coolant temp. over 212 degrees, both fans off over 35 MPH. I just do not like the idea of running the fans just because the A/C compressor is on.