Stock R4 compressor MOD and E-fan hook up HOW TO

[kewljay223]

I would let the pcm control the fans based on ac pressure and speed like stock. Cooling fans dont normally need to be on high and they dont need to be on above 30 mph for anything.

The pcm still does controls the fans like stock. the only thing i did was make them turn on high when the AC is on. do you have another suggestion on where i should tie the wire in that would actuate the BYPASS relay and any reason why that would be of better benefit than what i have shown? The only benfit i could maybe see is that they wouldnt be on constantly... ????

[fabianss357]

Nice write-up kewl, im subscribing for future refrence.
Mine right now is routed just like droopy, I mean exactly down to the blue tape closing up the water pump ports lol.
He turned the neck not for belt clearance but for the tensioner to clear.


Droopy what pullies did you swap and what size belt did you use if you dont mind me asking.
I need a belt and to turn my water neck still.

And oldspimp, the ls computer needs to have the ac signals from the original vehicles ac ccontrollers.
Thats not easy to do on these older trucks since most of their ac signals are voltage + and - signals not serial data that the ls pcm requires.

[droopyzda1]

Thats exactly why I turned the water neck. For pulley clearance. As far as the belt goes, I forgot. !! Actually Mickeymotormount was the one who told me the part number and I went to the auto part store. They did not have the exact one but cross referenced it and it fit perfectly. I also got a clothes line and wrapped it around the pulleys the way I wanted it routed and that was the same size that mickey stated.

As for the idler pulleys, I simply mixed and matched the ones from the 5.3 set up and the ones off my old 4.3 tbi pulleys and they worked perfectly.

[Mickeymotormount]

Nice write-up on the A/C 'Jay. Just goes to show you, there's more than one way to skin a cat.

Droopy did the same setup as I did. He used the original 4.3/5.7 liter tensioner. That requires turning the water neck some for clearance. And by comparing pics I noticed that your compressor is higher and closer to the water neck than ours.

[kewljay223]

Nice write-up on the A/C 'Jay. Just goes to show you, there's more than one way to skin a cat.

Droopy did the same setup as I did. He used the original 4.3/5.7 liter tensioner. That requires turning the water neck some for clearance. And by comparing pics I noticed that your compressor is higher and closer to the water neck than ours.

hey mickey!!! haha i know you read my writeup of this in my build thread so thanks again for the compliment! but i took bestills suggestion to make a writeup on it so everyone could see and possibly get stickied, since theres not many threads about making the ac working for our trucks. so i made it more detailed. but your right, there are many ways of doing this. jsut thought id share my way since i think its a really easy and cheap way of getting it going. just trying to give back to everyone that made this whole swap possible for me you know?

[Oldspimp]

I guess I skipped over the data line part of the thread. I thought it was just a matter of adapting high and low pressure switches and sending signal to the pcm, my bad. It just seems wasteful to me to have the fans on high when your on the hi-way cause all thats doing is slowing down air flow. I bet relays could be directly wired to pressure switches for a little more control over the fans, I think some old school switches are even adjustable.

[kewljay223]

looks like droopy and fabi had the same idea. hey mickey, how is yours done? you never really specified.. is it like theirs? i posted this thread to show how i did since its pretty simple to do but if any of you want to show how you did it i could care less if you use this thread to give details. the more the better for the comunity.

@ oldspimp... i see what your saying about the air movement at highway speeds by slowing it down. makes sense. but my 2 16" fans can move some serious air at full speed so i dont think it will hinder it that much but its still a valid observation. i did try and utilize the pressure sensors to control the relays and i couldnt figure out exactly when they would switch on and off. the one on the condenser and the high pressure on the back of the pump. also not all the pumps have the high pressure sensor on the back. depends on the setup that your year truck has. so i figured having the fans on anytime the ac was called for would be more on the safe side. thats why i was asking if you had any suggestions on where else to hook the wire up. im open to suggestions.

i just know that how i have it set up works great and that is why i shared. keep the other solutions coming though for the rest of us.

id still like to know what year truck you have droopy. is it a 95+ or 94-???

[droopyzda1]

id still like to know what year truck you have droopy. is it a 95+ or 94-???

Mine is a simple basic, plane Jane 1994 W/T (work truck). No cruise, no power locks, driver side window is manual but passenger is power (go figure). I do have the luxury of the a/c though. I still have to wire it and the e-fans. I love the write up u did. Just all the schematics kinda shares the hell out me. I thought I was done with the schematics when I went thru the truck's wiring and LS stand alone harness !! My e fans are a simple two wire generic from ebay with two 4 wire relays. They are up next for wiring. I had the pcm reprogrammed from the guy from lt1swap.com and he added another fan control to it. So I added an extra wire to the pcm connector

[Mickeymotormount]

'Jay, mine is like theirs, or like this: http://67-72chevytrucks.com/vboard/s...d.php?t=510656

[kewljay223]

Mine is a simple basic, plane Jane 1994 W/T (work truck). No cruise, no power locks, driver side window is manual but passenger is power (go figure). I do have the luxury of the a/c though. I still have to wire it and the e-fans. I love the write up u did. Just all the schematics kinda shares the hell out me. I thought I was done with the schematics when I went thru the truck's wiring and LS stand alone harness !! My e fans are a simple two wire generic from ebay with two 4 wire relays. They are up next for wiring. I had the pcm reprogrammed from the guy from lt1swap.com and he added another fan control to it. So I added an extra wire to the pcm connector

Yeah i had branden do my pcm also but i had to add 2 wires... one for low and one for high as i stated in the second post. did you already have one wire for fans??? kinda odd.. and it sounds like your fan setup will be basically the same as mine which means your going to need to add the 5 pin (S.P.D.T) switching relay unless your only planning on having them on high speed all the time?? not sure what you have in mind. but hit me up if you need any help with it. Im no stranger to electricity.

and mickey, did you have to go out and find that bracket at a JY or something? it didnt come with your truck right? i was just trying show guys they could use the one that came with the 350 instead of having to buy another one and have to hack it up anyway. lol