electric fan question

[dman1982]

maybe a dumb question but I'm running dual fans on my 5.3 k10, the one fan stays on as soon as i turn the truck on, the other one will come on once the motor gets up to 200 degrees or so (which has only happened a couple times) my truck will not get much above 150 degrees, how can i fix this and has anyone else ran into this issue? it throws a code for poor performance or something like that

[LockDoc]

Originally Posted by dman1982

maybe a dumb question but I'm running dual fans on my 5.3 k10, the one fan stays on as soon as i turn the truck on, the other one will come on once the motor gets up to 200 degrees or so (which has only happened a couple times) my truck will not get much above 150 degrees, how can i fix this and has anyone else ran into this issue? it throws a code for poor performance or something like that

You have to set the fans up in the tune. Mine did the same thing until I had the fans re-programed in the tune. I think normally the PCM/ECM/VCMs are programed for 1 fan so the second fan gets power all the time.

The LS engines are designed to run hotter for efficiency. My fan1 kicks on at 200º and fan 2 at 215º. Fan 2 never runs.

LockDoc

[dman1982]

Originally Posted by LockDoc

You have to set the fans up in the tune. Mine did the same thing until I had the fans re-programed in the tune. I think normally the PCM/ECM/VCMs are programed for 1 fan so the second fan gets power all the time.

LockDoc

i see...well crap...thanks tho

[LockDoc]

Originally Posted by dman1982

i see...well crap...thanks tho

I added to my above post....

LockDoc

[dman1982]

Originally Posted by LockDoc

I added to my above post....

LockDoc

thanks man, i appreciate it....guess ill have to get another tune done...

[ls1nova71]

Originally Posted by dman1982

maybe a dumb question but I'm running dual fans on my 5.3 k10, the one fan stays on as soon as i turn the truck on, the other one will come on once the motor gets up to 200 degrees or so (which has only happened a couple times) my truck will not get much above 150 degrees, how can i fix this and has anyone else ran into this issue? it throws a code for poor performance or something like that

Has it always done this? How is it wired? Could be a wiring issue, if the fan comes on as soon as the key is turned on, try unplugging the PCM connectors and then turn the ignition on, if it comes on then it's not being commanded by the tune/PCM, if it doesn't come on, then you need to see what your fan settings are set at.

[dman1982]

Originally Posted by ls1nova71

Has it always done this? How is it wired? Could be a wiring issue, if the fan comes on as soon as the key is turned on, try unplugging the PCM connectors and then turn the ignition on, if it comes on then it's not being commanded by the tune/PCM, if it doesn't come on, then you need to see what your fan settings are set at.

its always done this LS1nova, i unhooked the pcm and turned the key forward and no fan...so I'm guessing i need to retune?

['68 Newtricks]

(sorry, didn't modify my own harness) I've got both fans wired to my "low" temp ground signal from the harness. I also had a "high" temp wire but choose not to use it. To me, if you have dual fans, they should really both come on at the same time. If one is on, it will simply pull air from the least restrictive location..... the other fan opening, not from the other side of the fins. I also have an override switch to turn them on when my AC is on, so airflow is going across the condenser.

Check the wiring and tune I guess but think about just running off one ground signal.


edit: open fan hole comment is for those running shrouds, not fans directly mounted to radiator

[ls1nova71]

Originally Posted by '68 Newtricks

(sorry, didn't modify my own harness) I've got both fans wired to my "low" temp ground signal from the harness. I also had a "high" temp wire but choose not to use it. To me, if you have dual fans, they should really both come on at the same time. If one is on, it will simply pull air from the least restrictive location..... the other fan opening, not from the other side of the fins.

When wired like the factory does it, they both come on at low speed and high speed. On low they are run in series and high they are run in parallel so you're never pulling from just one side of the radiator.

[homemade87]

Originally Posted by ls1nova71

When wired like the factory does it, they both come on at low speed and high speed. On low they are run in series and high they are run in parallel so you're never pulling from just one side of the radiator.

This is correct, Both fans run 1/2 speed at the same time on low . The gm system requires a three relay system for it to work . If you only have 2 relays it will not do this . Also if your fan comes on at ignition on only ( no start up ) its either you have it wired improper or the pcm has a problem .

[elf w/capital T]

The three relay going to a vintage air trinary switch, anyone have a diagram i could follow for my build?