ANOTHER Nelson e-fan harness fails!!
Oct 11, 2010 | 09:36 AM
#11
Thread Starter
Staging Lane
Joined: Apr 2010
Posts: 53
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I purchased a Nelson e-fan harness when they first came out. They did replace the relays or switch brands because of problems with those original relays. He sent me (3) new relays at no cost to me to replace the original ones and I have not had any problems in 4 yrs.. Sounds like your fan relays wired into your AC relay and not controlled by your PCM. If this is the case than you are probably overloading your AC relay. If this is how you wish to have it wired, than your AC relay can be wired to energize you fan relay coils but your switched power should come from a separate fused power source.
Oct 11, 2010 | 09:39 AM
#12
Performance Trucks Sponsor
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From: san antonio, tx
Way to address the issue Farmtruc....What is the percentage of success with your harness's if installed correctly, and what are some of the problems you have encountered on "good installs" if any? I know mine must have been either the relays or something else..It was 100% installed anally correct..lol
During the summer we send out about 10-20 harnesses a month and very rarely have one come back. With that many going out, any supplier will have a few here and there that don't work.
But common issues with the harness not working:
Installer bends, breaks or doesn't seat the blue pcm wire correctly.
Grounds to alternator bracket is installed on top of the black painted power junction bracket and not directly on the aluminum alternator bracket causing a bad ground.
Relays go bad.
Possible contamination on terminals.
Oct 11, 2010 | 09:42 AM
#13
During the summer we send out about 10-20 harnesses a month and very rarely have one come back. With that many going out, any supplier will have a few here and there that don't work.
But common issues with the harness not working:
Installer bends, breaks or doesn't seat the blue pcm wire correctly.
Grounds to alternator bracket is installed on top of the black painted power junction bracket and not directly on the aluminum alternator bracket causing a bad ground.
Relays go bad.
Possible contamination on terminals.
But common issues with the harness not working:
Installer bends, breaks or doesn't seat the blue pcm wire correctly.
Grounds to alternator bracket is installed on top of the black painted power junction bracket and not directly on the aluminum alternator bracket causing a bad ground.
Relays go bad.
Possible contamination on terminals.
Oct 11, 2010 | 09:42 AM
#14
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From: san antonio, tx
The only way the harness can be at fault is if it's not working correctly, which you said it was for a long time, so it's wired correctly.
There is no reason why a stock fan needs more than a 40amp relay.
Clean and check all your connections.
Oct 11, 2010 | 09:45 AM
#16
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From: san antonio, tx
Not sure if you need to go to 50amp relays, but for comparison, the flex fans demand a lot and they do fine with 40amp relays.
hope this helps,
Oct 11, 2010 | 10:06 AM
#17
i have been using the nelson harness since '06. i just recently swapped from the ls1 e-fans to the 05 efans/34" radiator. the 05+ fans pull a lot more power than the ls1 fans. i have never had an issue. not even with the high amp draw of the larger fans
Oct 11, 2010 | 10:34 AM
#18
Not familiar with the design of the harness in question, but I do hope that everyone's installs are properly fused.
I built my own harness and use 30A fuses on the fan relay supplies and a 10A on the hi/lo relay supply as per factory wiring diagrams for a fully PCM controlled setup (3 separate supply wires and fuses). I have never blown a fuse with my Spal fans. 40A relays should be fine.
I built my own harness and use 30A fuses on the fan relay supplies and a 10A on the hi/lo relay supply as per factory wiring diagrams for a fully PCM controlled setup (3 separate supply wires and fuses). I have never blown a fuse with my Spal fans. 40A relays should be fine.
Oct 11, 2010 | 11:09 AM
#19
Thread Starter
Staging Lane
Joined: Apr 2010
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I had tried To get Nelson to send me a new harness with the return off the one on my truck.. It was one month out of warranty.. The harness wasn't well built.. Sorry don't mean to dawg the product but When you buy something and install it you expect t to work properly.. If you can't install that harness the way it needs to be in order for fans to work properly you have no business modding your vehicle..I will try to upgrade from a 40 amp relay to a 50 and see what happens..
Oct 17, 2010 | 12:01 PM
#20
Teching In
Joined: Apr 2008
Posts: 45
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My son has a Nelson harness on his truck. Sometimes when we pop the hood we can hear one of the relays clicking like it's getting intermittent power/signal to it. Has anyone had this issue and how did you fix it?
Thanks
Randy
Thanks
Randy