Electric fan conversion worthwhile?

Badass69 · April 30, 2013

This should get stickied someday on this site and maybe I should do the write up lol. If your truck has the 34 inch core radiator you need to do nothing more than remove your shroud and clutch fan and drop in the e fan assembly. If you have the 28 inch core you need the larger rad first. The electric fans use the same style bolts as the radiator does so you need 2 more of those as well. Another thing I always see is people limiting themselves to the gmt800 fans...... don't. Idiots want a mint for them and they aren't worth anything honestly. The gmt900 trucks use the identcal arrangement and have more options for fan combos. I have the largest ones available on my 04. They are from a nht 6.2 powered 2011 truck and have a 7 and 9 blade combo. The set on my 05 is from a 4.8 powered 07 gmt900 in the 5 and 7 blade flavor and yes they work fine too. The ones on my 04 and my buddies 05 1500 hd are new replacements I paid about 165 dollars for from rockauto. New is cheap.... and they work very well.

I personally have the ls1fans harness ( blackbear sells this one) and oem. Oem is nicer although they do both work. The oem harness can be from a junkyard or bought new. I went new and it was only around 175 bucks. Its the entire front harness so I just stripped the e fan part out and put on new loom. You can't tell my 04 didn't come factory with e fans as its all oem. The only part missing going this way is the jumper harness to the pcm. The factory setup has a connector with the 2 trigger pins to the pcm that the gm harness does not incluse. Any automotive electrical supply place can get get the weatherpack connector and pins. Then you just need the wire. Or do like me and steal it from a junk harness.

Since your are 03 up its plug and play. No matter which harness when you put power and ground to the fans plus plug the 2 trigger wires into the pcm the hard part is done. Any tuner can turn on the outputs in the trucks pcm and set your desired speed and temp settings. Voila... they work as all the 05 + plus oem equipped half tons do. I self tune with efilive and I set my control tighter than gm does and they work well.

Yes the 145 amp alternator is pretty well a must. You need the alternator and 3/4 inch longer belt. Just install it and you are done. They aren't expensive either.

No one talks about this but e fans help in cold weather too. The viscous clutch fan freezes on and will overcool the engine at idle to the point the thermostat closes and the truck starts to cool off. Once I did e fans that has never happend again. On the cj2 digital dual climate control trucks your a/c clutch is locked out below freezing so your fans will only run on temperature. Oddly my friends cj3 equipped manual climate truck does not do this and since the a/c clutch cycle the e fans will kick on and off based on system pressure no matter the temp outside... annoying but I can't fix that. Just another reason I won't buy a truck without digital climate control lol.

Chris · April 30, 2013

This should get stickied someday on this site and maybe I should do the write up lol. If your truck has the 34 inch core radiator you need to do nothing more than remove your shroud and clutch fan and drop in the e fan assembly. If you have the 28 inch core you need the larger rad first. The electric fans use the same style bolts as the radiator does so you need 2 more of those as well. Another thing I always see is people limiting themselves to the gmt800 fans...... don't. Idiots want a mint for them and they aren't worth anything honestly. The gmt900 trucks use the identcal arrangement and have more options for fan combos. I have the largest ones available on my 04. They are from a nht 6.2 powered 2011 truck and have a 7 and 9 blade combo. The set on my 05 is from a 4.8 powered 07 gmt900 in the 5 and 7 blade flavor and yes they work fine too. The ones on my 04 and my buddies 05 1500 hd are new replacements I paid about 165 dollars for from rockauto. New is cheap.... and they work very well.

I personally have the ls1fans harness ( blackbear sells this one) and oem. Oem is nicer although they do both work. The oem harness can be from a junkyard or bought new. I went new and it was only around 175 bucks. Its the entire front harness so I just stripped the e fan part out and put on new loom. You can't tell my 04 didn't come factory with e fans as its all oem. The only part missing going this way is the jumper harness to the pcm. The factory setup has a connector with the 2 trigger pins to the pcm that the gm harness does not incluse. Any automotive electrical supply place can get get the weatherpack connector and pins. Then you just need the wire. Or do like me and steal it from a junk harness.

Since your are 03 up its plug and play. No matter which harness when you put power and ground to the fans plus plug the 2 trigger wires into the pcm the hard part is done. Any tuner can turn on the outputs in the trucks pcm and set your desired speed and temp settings. Voila... they work as all the 05 + plus oem equipped half tons do. I self tune with efilive and I set my control tighter than gm does and they work well.

Yes the 145 amp alternator is pretty well a must. You need the alternator and 3/4 inch longer belt. Just install it and you are done. They aren't expensive either.

No one talks about this but e fans help in cold weather too. The viscous clutch fan freezes on and will overcool the engine at idle to the point the thermostat closes and the truck starts to cool off. Once I did e fans that has never happend again. On the cj2 digital dual climate control trucks your a/c clutch is locked out below freezing so your fans will only run on temperature. Oddly my friends cj3 equipped manual climate truck does not do this and since the a/c clutch cycle the e fans will kick on and off based on system pressure no matter the temp outside... annoying but I can't fix that. Just another reason I won't buy a truck without digital climate control lol.

Do a whole how to and pro/con list and u will sticky it

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Babyhauler · April 30, 2013

I went from an 02 w/ mechanical fan to an '05 w/ electric fan.

One thing I like is it is much quieter. Especially in the summer when the mechanical fans sound like a school bus taking off. The ac cools better at idle.

I had my pcm modded to add the fans on the '02, but the deal on the '05 happened & I never changed it. My son drives it now, he can tolerate the noise.

As suggested, try to find a factory set, do the pcm, harness and alternator. This should work right & have the least amount of trouble.

Good luck,

Babyhauler

Pdfire119 · May 1, 2013

Wow thanks for all the great info, I found factory e fans on line used with connectors to the fans and part if the wire harness stil attachef where the 2 meet up and go together unto the rest if harness do I just need to splice and wire this part into rest of harness, and how hard is the jumper pins to wire up and where do they plug into. Saw black bear coming to houston for tunes in may, want to get everything done and ready by then to get tahoe tuned. Thanks for all the help

Chris · May 1, 2013

You need to get a harness from a place like LS1fans.com and have your truck tuned so the pcm knows when to turn the fans on and off

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Badass69 · May 2, 2013

You need to get a harness from a place like LS1fans.com and have your truck tuned so the pcm knows when to turn the fans on and off

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Or just get the oem harness and have a cleaner install with no relay failures. I have both ways and will do only oem now but thats just me.

Chris · May 2, 2013

Something I did not know

Pdfire119 · May 2, 2013

Ok found one oem aux cooling fan harness for sub/tahoe for about 30 bucks, if I go with it is reprogramming pcm still needed?

txab · May 2, 2013

Yes

Badass69 · May 4, 2013

That is the oem harness after you take the time to strip it from the rest of the harness it comes with. If you really wanted to you don't have to strip it but then you end up changing the entire front harness of the truck including all the lights, air bag sensors etc. The little fuse block snaps in underhood fuse center once you pop the cover off. All GMT800's have the mounting tabs for it. The picture above is missing the cover that comes over the relays and whatnot.

That blank open spot is where that harness fuse box snaps into place. Below is the GM photo of the e fan harness assembly. The part number for it is 15912597. I think I paid about $172 for it and it comes complete. The only portion missing can be seen in my first posted pic which is the plug with the 2 trigger pins that you terminate in the PCM connectors. The connector is a 2 pin GT 150 and you can get it from places like http://www.waytekwire.com . You'll need a connector, seals, TPA and terminals. You'll also need PCM pin terminals(you can get elsewhere). Or..... you can get it from a wrecker out of an e fan truck. I would say take the whole front harness too, which you can...... but most wreckers here want as much as I paid for the new one.... plus I have to deal with apes pulling it out for me. The LS1fans harness is easy too but I like the oem stuff. I haven't had any issues with my LS1fans harness personally and have had it for about a year and a half on the truck now. That said I still like the factory one better and will be swapping out my 05 1500HD for the factory harness eventually. My 04 has the oem one on it now and it looks oem to the truck...... because it is, lol.