.....

 

I think your setup is fine - just another option. I would hold off on tapping the a/c line. I don't like messing up wires unless I HAVE to. First, hook up your temp probes and see how the temps are under high ambient temperature while running the a/c - if things get too hot, then you might want to run one of the fans off the a/c compressor circuit.

 

I've never had a problem with the factory efans in my 05 yukon. I'm beginning to wonder if the best route is to get a harness and alternator from an 05+ out of a junkyard and work them in. Not sure how the charge controller on the 05+ would integrate with the older trucks though. Perhaps it could be fixed with a tune? IDK.

I know the pre-2005 models had a lower output alternator. My 05 has a 165a alternator versus the 145a in the 04-older (which i believe the trucks used lower outputs on both than the SUVs). Maybe the lower alternator output is causing the issues? The voltage isn't different, but the current is. The fans pull the greatest load at initial startup where a surge is needed to get the motors turning. I see some people run a smaller pulley on the alternator to boost output, but I'm not convinced a higher shaft speed can overcome the physical difference of a larger, more powerful alternator. The relays could be blowing simply because they aren't getting enough current to operate correctly.

 

99-05 had 105A alternators, 05+ have 145A. I have a 200A.

 

I actually found a new controller from Derale that has an a/c input and a 30/40 amp relay. Supposed to be here today, so I will do a write up soon! It runs both fans at full speed whether it's temp based or a/c based. I am considering running an override switch though for when I'm on the interstate with the a/c on. I'm not liking the idea of tapping the line, but I'm guessing with Florida heat and humidity, and my a/c already getting warm with clutch fan at idle it'll be needed.

Those running a higher output alternator... Are any other modifications required, or just physically changing out the alterator?? I've always loved mechanical work, but electronics are not my friend.

 

There was a 130A alternator used in '02 - I assume other years also. I have that in mine along with the factory '05 harness. I have no issues.

 

I know the 2004 Escalade had the 145A alternator. When I put the efans in I had no problem with cooling issues even pulling an enclosed trailer weighing 7800lbs in 90 degree weather.