Just installed 05 fans with nelson harness (sorry white1, couldnt wait) and 145a alternator..
These fans definately take some power...the lights will dim with the ac on..

What is the resolution to this?

Larger wiring off the alt and batt?
.5 or 1.0 Capacitor in line of fans?

Thanks!!

 

No solution that I know of. I also installed a 145 amp alternator. At one point I was going to upgrade the primary power wire out of the back of the alt. to a larger wire to see if that would help. Recently I found while logging some highway driving with the AC on that the PCM was pulling almost 16 degrees of timing when the AC clutch engaged. I fixed that and it helped a lot but they still flicker slightly.

 

Well that could explain why the truck seems so sluggish with the ac on (more than the norm)...even with the Jesse Bubb tune

 

Related to the 05 fans and wiring...

I had my engine installer do the fans with a Nelson harness at the same time as he dropped in the engine. He wired both fans through a single relay, and while stuck in traffic this weekend the relay melted! I was able to unplug one fan and swap the middle relay to the first location and get moving again, but need to address the problem. How are the fans supposed to be wired? Anywone have a diagram?

 

Mine does the same thing...when the ac compressor kicks on and the fans come on high, the lights dim momentarily & the voltmeter dips, but then quickly returns to normal. (I also have 05 efans & the 145amp alt) The combination of the compressor and fans are a pretty big load on the system. Maybe with some extensive tuning (ac idle up settings or whatever) and a stronger alt and battery, this could be remedied, but I've learned to live with it as "characteristic". If someone ever does come up with an easy fix, hopefully they'll do a write up, until then I'm just living with it. I don't have any problems when the fans come on low so I'm pretty satisfied.

 

one thing I noticed, the 05 fans draw alot more power than the LS1 fans.

as for the guy with the Nelson harness installed wrong:
How? Nelson didn't supply the harness with the plugs for the fans? after that it's just a positive, negative and a/c wire tap... I have the original "white1" prototype 3 relay harness and it has worked flawlessly

 

Larger wiring and a 1.0 Farad capacitor will help soak up the starting current and atleast will probably keep the the dimming at a minimum. Also, make sure if you do use a capacitor 24volt or higher rating will last longer than lower rated ones.

 

I have been having issues with the Nelson harness and relays. My thread here:
https://www.performancetrucks.net/fo...d.php?t=369636

One of the guys tested current draw on initial fan startup and it got as high as 75 amps then backed off to 7-8 amps after they spun up to speed. A cap would probably help a lot, that's a great idea.

 

yeah i want to see if the cap helps. someone needs to try it out.

 

Like Thunder, I'm already worn out on overheating troubles...and have switched back to the clutch fan several times while sorting this out. I'm thinking about switching to a controller instead of harness/PCM turn on...looking at one of the www. dccontrol. com units.