Hey guys in the process of my 99 sierra 5.3 build... I was wondering what are the NEGATIVES if I install one fan to the ac wire and the Other one Direct to Ignition 12volt instead of to the Pcm.. Reason being I dont feel like getting my pcm reprogramed at this time!

thanks
Julio

 

It will take longer to heat up, and may never reach full temp if you live somewhere really cold in the winter. May also shorten the fan life, but you will probably sell the truck before that happens.

Its not hard to put it on a triple position switch for off-low-high manual operation.

 

thanks Atomic..I live in Miami so its Always B*LLS sweaty Hot!!!! I did read in a post about your set up ..How exactly would it work ?
I was thinking about just running a additional Coolant Temp switch that would activate them , but not to sure on Reliability !

 

It depends how your harness is setup, but if it has the typical low and high wire leads, simply use a DPDT 3 position switch setup like this:

[low] [high]

[ground] [ground]

[low] [empty]

Flipping it up will ground the low wire, turning it on low. Flipping it down will ground both the high and low wires turning them on high, and keeping it in the middle position will not turn them on at all.

 

Ok.// Only concern is Jumping in the truck and Forgeting to switch them on!!!!

 

You could put the "ground" wire on a relay that switches based on ignition power then just leave it in the "low" position most of the time.

 

lets see..Im in the process of putting the front end back on as i purchased the truck with a minor fender bender!!! Im gonna try my luck with the direct set up... Just gotta figure out wich wire (green i think) is the one for the Ac

 

What harness are you using?

 

Planning on Running 2 relays and just Making it myself!!! Not to sold on spending $98 bucks on wires and a few relays !!!!

 

I think I spent about $50 making mine, but it does look nice with 10ga wire and crimped/soldered connectors.