Found my problem!!!

[weq92f]

Purchased and installed a dual fan harness some time ago. While chasing other issues noticed the lead positive to the harness was very hot. Determined it was a 10 awg wire, traced it back into the harness to find that it was split to feed two relays with 12v. One 10g wire feeding two 10g wires. Both fans on were almost enough to melt the lead wire!

-klb
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[weq92f]

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The harness builder put in a 40A inline fuse on the lead wire! My fans are drawing only about 24A total when on full tilt ( again...enough to heat up the lead wire big time).

The single wire feeding the two wires should have been 8awg right? Or is it a bad idea to wire things up this way?

My intention is to wire each relay direct to my bus bar with individual fusing using the 10 awg size already in use. That should safely handle 12A per fan.

-klb

[weq92f]

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Went ahead and replaced the single lead with two. I did not find any bad connections from the bus bar to the split pictured. Harness ground was solid. This config is better! I may have to look into ( actively manage ) the fan grounds next if problems persist...

-klb

[67C10Step]

I think you are on the right track. I call wires electron pipes. Gotta have a big enough main pipe to feed all the smaller pipes.

Have you confirmed the draw by your fans? If not, you may want to do so just in case something is amiss in the load.

I have found more problems with bad grounds in autos than I care to remember so managing those is never a bad idea.

Good luck and good work.

[kwmech]

24a should not bother a 10ga wire. Factory alternators in these older trucks only had a 12 ga lead coming off of them. Loads on them can jump up to 40a or more easily.

[weq92f]

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With the lead broken out into two 12v feed wires, one for each relay, the fans run good and the leads do not get hot.

It is possible my fans are pulling more juice than advertised...which would explain the previous issue.

All good now.

-klb