Helping out my LS1 fans

[SlammaDingdong]

The Nelson harness and LS1 fans (00' Camaro in my case) is a great setup, but I'm going to add a flex-a-lite #108 (pusher) to help things out.

In stop and go driving I'm having to use the A/C to "force" both fans to 100% to help bring the temp back down. My "normal" (constant motion) running temp is about 185 on the stock guage. In stop and go, or after running hard then stopping, it peaks at about the 210+ mark and the weather hasn't really been that hot yet. This is happening on 75-80* days, and NOT towing anything.

When the fans are running at just 50% (A/C not on), they just ain't bringing the temp down unless the truck is moving. Since my timing is biased for a 160* tstat, I don't like this. I'm not gonna wait until 98* temps this summer to let this be a problem. So hopefully an extra 800 cfm fan will help out.

Before the e-fans, but with the 160* tstat, the temp guage stayed at the 185 mark and never really moved.

Here's the configs I'm considering:

On Nelson harness, disconnect A/C exicter wire from A/C compressor wire and connect to PCM exciter wire. Control aux fan via relay energized by A/C compressor wire.

PCM on only: Both LS1 fans 100%
A/C on only: Aux fan on
PCM on + A/C on: Both LS1 fans 100% and aux fan on

-or-

Leave Nelson harness connections in place. Control aux fan via relay energized by PCM exciter wire.

PCM on only: Both LS1 fans 50% and aux fan on
A/C on only: LS1 fan 2 on 100%
PCM on + A/C on: Both LS1 fans 100% and aux fan on

-or-

Leave Nelson harness connections in place. Control aux fan via relay energized by PCM exciter wire AND control aux fan via relay energized by A/C compressor wire.

PCM on only: Both LS1 fans 50% and aux fan on
A/C on only: LS1 fan 2 on 100% and aux fan on
PCM on + A/C on: Both LS1 fans 100% and aux fan on

I'm leaning towards the last one. BTW, the fan being added only draws 6.5 amps.

Later I'll add some switch control in the cab, but wan't to avoid messing with a fan switch while driving around town. I'm already having to mess with the damn A/C switch

Another thing I'd like to do is change A/C activated fan control from compressor switch to the low pressure switch discussed in this excellent thread http://forum.ls1truck.com/index.php?showtopic=3582
Has anyone got this method to work?

[RedHeartbeat]

I had the same problem with my LS1. I found that it is not that the fans are not cooling enough but there is not enough water flow. If you rev the engine to about 1500 rpm you get good water flow and the engine stays nice and cool. At idle there just does not seem to be any water flowing. I turned the idle up in the PCM to 1000 rpm and I didn't have quite as much of a problem with the temps going up. Mine was heating up to 250 while idling in 60 degree weather and as soon as I run the rpm up for about 15 seconds the temps came down in a hurry.

[SlammaDingdong]

Thanks for the feedback RedHeartbeat

Earlier today, when my temp peaked at about 210*, with both fans turning at 50%, I tried the engine rev test. It did bring the temp down slighty, but went right back up at idle. As soon as I kicked on the A/C (both fans 100%), the temp fell rapidly back to the 185* mark. I'm thinking in my case the extra fan capacity and rewiring may help. My fan and relays will be here tomorrow. We'll see...

[SlammaDingdong]

I did some mock up testing with some extra relays, diodes and the Nelson harness. Using some creative jumpering I was able to establish a nice configuration for maximum cooling:

PCM on only: Both LS1 fans 100%
A/C on only: LS1 fan 2 on 100% and aux fan on
PCM on + A/C on: Both LS1 fans 100% and aux fan on

I may be getting close to needing a 135 amp alt using the 3 fans. When all the relays activate for the PCM on + A/C on condition, I do see a momentary charging drop to about 13.5V. It does recover to just over 14V, but I don't like to see that voltage drop.


Now time to integrate my stuff into the Nelson harness. When it's all done I'll post a review on how it went...

[Hit Man X]

I like this Aux Fan idea, hell my Benz has one. lol

Tell me if this is possible to wire up...



Coolant Temp with two speeds... 183-187°F on low speed (50%), 189° high speed (100%). Numbers around there.

Low Coolant Temp (only AC on)... 50% low speed main fans, 100% aux fan. I never had a cooling problem with my big radiator and LS1 fans.

Coolant Temp and AC Demand... both at 100%. Should come down to 50% for the main E-fans pretty quick with the larger 3/4 ton radiator I have and the larger '05 fans.



What fan are you looking at that will fit in that area behind a rad cooler?

[SlammaDingdong]

I went w/ a FAL #108, set up it in pusher mode, and used brackets to mount it in front of the A/C condenser. It just had clearance "inside" the hood latch support bracket. I had to ditch that piece of angle bracket that I guess was for mounting optional OE stuff; it provided no structural integrity anyhow.

Using a diode and 2 relays I modified the Nelson harness so the fans behave like this:

A/C on only: LS1 fan #2 and Aux fan at full power
PCM temp trigger only: LS1 fans #1 and #2 at full power
A/C on + PCM temp trigger: All 3 fans full power

I added a remote switch in the cab that will run all 3 fans at full power.

The setup works pretty nice so far and has met my expectations. But I REALLY need to upgrade my alternator ASAP to close the deal. The aux fan probably helps the condenser out to some degree, but I think another benefit is that it provides the LS1 fans w/ an air charge so to speak. That's gotta help their efficiency.

Final step (other than new alt lol) is to modify so the A/C trigger comes from the hot lead on the accumulator switch instead of the A/C clutch. Haven't physically verified this can be done yet, but GMCwantsLS1 thinks it's doable.

I really owe some on this one. Will also do a simple diagram of the Nelson harness mods in Visio and turn it into a GIF.

Jeff

[SlammaDingdong]

Originally posted by Hit Man X@Jun 20 2005, 06:38 PM
I like this Aux Fan idea, hell my Benz has one. lol

Tell me if this is possible to wire up...



Coolant Temp with two speeds... 183-187°F on low speed (50%), 189° high speed (100%). Numbers around there.

Low Coolant Temp (only AC on)... 50% low speed main fans, 100% aux fan. I never had a cooling problem with my big radiator and LS1 fans.

Coolant Temp and AC Demand... both at 100%. Should come down to 50% for the main E-fans pretty quick with the larger 3/4 ton radiator I have and the larger '05 fans.



What fan are you looking at that will fit in that area behind a rad cooler?

Hey Hit Man, I may have misunderstood the original wiring question. Are you takling about using a VSC module along with the Nelson Harness, then modifying so that the aux fan is integrated?

[TXsilverado]

instead of adding more fans, why not look for problems? im using fal 292's with nelsons harness. i left my truck parked for about 30 minutes while my mirror read 105* (texas is a oven) and my temps never went any higher than i would expect. the fans never even kicked onto high. im using a 160 thermo. maybe a new radiator is in need. im sure 3 fans are putting a whippin on your alt.

[SlammaDingdong]

Originally posted by TXsilverado@Jun 21 2005, 12:19 AM
instead of adding more fans, why not look for problems? im using fal 292's with nelsons harness. i left my truck parked for about 30 minutes while my mirror read 105* (texas is a oven) and my temps never went any higher than i would expect. the fans never even kicked onto high. im using a 160 thermo. maybe a new radiator is in need. im sure 3 fans are putting a whippin on your alt.

You're right, the ultimate solution is a 34" radiator w/ the big 292s or 05' OE fans. However, my path started with a 28" radiator, eBay bought LS1 fans and the Nelson harness, so that's where I'm at. Doing the aux fan and modified wiring did the trick for now. My 105A alt is getting whipped now, but I probably needed to upgrade that even w/ just the LS1 fans. Ordering that next week.

[TXsilverado]

im still on the 28" radiator. lots of people use the ls1 fans without any problems...is it making a seal around your radiator?

edit. and they are pulling air towards the motor and not pushing air out right? i had to reverse the wiring on my harness whe i got it because they were pushing air instead of pulling. if you put a peice of paper in front of the grille with the fans going it should suck the paper onto the grill, not blow it away.

make sure you do the paper test because mine felt like they were pulling air when i put my hand down in the motor compartment but it was really pushing hot motor air through the radiator.