rpm-inc

Installed e fans yesterday on my 04 with an ls1fans.com harness.

Used an 05 avalanche as a basis for the on off temps and ac pressures.

Using VCM scanner to force the fans-


Fan 1 on, fan 2 off-both fans low speed

Fan 2 on, fan 1 off-driver side fan off, passenger side high speed

Fan 1 on, fan 2 on-both fans high speed.

Is this correct?

01SilveradoJakee

1 fan is going to be for AC when the compressor comes on a needs to pull air across the condensor. Then you will have both fans on for the truck when it gets to a certain temp, (my low speed is set for 185*) and will stay on until the desired temp is reached, then both fans will come on at high speed (again mine is set at 195*) and stay on until desired temp will run. For what I have read and seen, thats close to factory specs.

rpm-inc

The reason I ask is with the ac on and not up to temp, both fans come on low. According to the instructions, one fan should come on high. Both fans do come on low at 205 which is what I have fan 1 currently set at.

rpm-inc

Here is the response via email from ls1fans.com

Ryan,

Yes that is correct. If using Hp Tuners this is a series parallel harness and must be tuned accordingly. HPT 2 fans settings is not the same. It is set up different on HPT and tuned completely different.

I use efi live and can not help you with HPT


Beware wrong setting here can kill the harness or worse burn up a truck.

Sent from my iPhone

> On Feb 26, 2018, at 5:42 AM, ryan <rpminc1@comcast.net> wrote:
>
> Got your harness installed this weekend. Not sure if they are working as they should. So with hp tuners vcm scanner to force the fans-
>
> Fan 1 on, fan 2 off-both fans low speed
>
> Fan 2 on, fan 1 off-driver side fan off, passenger side high speed
>
> Fan 1 on, fan 2 on-both fans high speed.
>
>
> If this is correct, and it probably is, maybe my tune just needs some work. I copied an 05 avalanche, and just lowered the on off temps a bit.
>
>
> Thanks.

tippmann243

iTrader: (1)

on a series parallel harness, both fans should be on at half speed for low and both should be on full speed for high.

a 2004 should be able to cycle fans on off and between high and low based on both coolant temps and AC pressure.

in the tune, ac pressure should be set low enough that as soon as the AC kicks on the fans come on low speed. they should then kick to high speed when the AC hits a certain pressure.

same with coolant temps.

to make this work properly the tune needs to be setup so that fan 1 controls stay on when fan 2 is commanded.

for example based on temps

fan 1 on at 200 off at 195
fan 2 on at 210 off at 199

so even though fan 2 is on at a coolant temp of 212, fan one is also still on.

the results you saw with the scanner are completly normal.

Atomic

iTrader: (42)

This is correct on your truck. Everything is fine.

Forcing high speed (Fan2) without low speed (Fan1) first being on will never happen in normal operation. The fans will always be both on low, then both on high during actual use.

01ssreda4

iTrader: (87)

after examining the diagram, lighting off relay 2 only will give a fan 2 high operation with fan 1 remaining off. Is there any instances where the computer may command only relay 2 on?

Atomic

iTrader: (42)

No. Never in normal operation.

rpm-inc

OK, thanks. The guy that makes the harness doesn't know how the system operates, I guess. Doesn't give much confidence in the harness itself, but it does look well made.