Know I was talking about the fan harness and I was looking at some used ones on eBay and it looks like more stuff there then you need. I’m probably all screwed up but it looks confusing? Lol. I will take another look and try to make some sense of it. Have you had any experience with using the factory harness?

 

no but that is what is usually retrofitted to other GM trucks that have the clutch fan to make it work like OEM. some have to get it enabled on their PCM with a tune. its wildly used especially in the LS swap forums.

 

I will do some more digging. I have plenty of time to gather parts and get it figured out. It’s hot here and I’m not doing anything until it cools down, like September or October.

 

I came across this obviously you would have to tailor it for the hummer but useful info

 

That’s funny... I found that video and that’s where I got the idea for the 2009 ESCALADE fan setup. It’s the same part for many vehicles. But I wanted the 7/9 blade fans

 

A couple of members on Performancetrucks forums pulls and sells the factory harness. It is by far better than any aftermarket one and yes, it does directly attached to the under hood fusebox and is a proper series/parallel relay setup with the correct relays and fuses. A couple of caveats for PROPER control of factory style electric fans though. You have to run two wires to the engine PCM and you need to have a custom tune done to enable them to be PCM controlled. The 08/09 H2's come with them stock too...

The way the PCM controls them for AC is based on the compressor head pressure so they run when they are needed, not always when the compressor is engaged for one. Two, they also of course run based on engine temperatures. Third they do not run above a specified vehicle speed (about 35mph but that can be adjusted with the custom tune) as there is no point since the air coming in the fro0nt of the vehicle is more than the fans can provide. Last the series parallel arrangement also runs them in a couple of different speeds and can run just a single or both fans. All of these combined make the fans last longer by not running them when not needed, further improves economy by not running them on max when not needed, etc.

Another important point is that there is no free lunch. Whether a clutch fan or an electric fan has to move air, that takes power. When both electric fans kick on high, your alternator suddenly becomes a LOT harder to turn as it has to increase its output. Most agree that the load is still far less than the clutch fan. Another benefit, far more room in front of the engine to work, less wear on the water pump bearings, no school bus roar of the clutch fan....

I've learned a LOT about this conversion over the years as I've done it the wrong way and have done it the right way.... You can also get an alternate underhood fuse box shroud that has a second smaller lid in the triangle section towards the firewall where the factory fans relay/fuse module installs specifically for accessing that. I'll get you the part number. Look at the performancetrucks forums under the classified for GM parts...

 

Thanks Mixmansc, I will check it out. I would rather have the factory harness but I didn’t want to have to strip the stuff out that I didn’t need. I see wiring and I panic. Cut, weld, bolt, fit I have confidence in my limited abilities but wiring not so much.

 

I found this harness and it seems to be good quality and the instructions seem pretty straightforward. I don’t know if it will fit my application. It seems to do everything the factory harness does.


https://www.bp-automotive.com/produc...v-fan-harness/

 

it should not be hard to strip the OEM harness. all you have to leave is what is going to the fans the rest should just pull out of the wire loom like the horn wires and headlight / turn signal, washer motor wires.

 

That’s the part that worries me and I am worried that I will take something out that I need. I was just looking at my fuse box and I didn’t see the space for the addition of that extra part for that factory fan fuse box. I will look at a 2008 box and see what they did different from the 2007