AC cooling with LS

[Andy4639]

I have had my LS swap for almost 2 years now and the AC has always done pretty good, well up til today anyway.

Started out just wanting to check the system to make sure it was ready for summer. Was not cooling down good like before so.... I hook my gauges up and pressures look ok.
Start the truck up and turn the ac on and before I could walk around to the front I see mist spray! High side hose on gauges has a pin hole in it! OK,OK gauges are 10-15 years old, Shut the truck off and got the quick connect undone. I may have lost a little bit. So any way I go to my buddies shop and ask to barrow his and the high side goes straight up while my buddy says cut it off.
No fans coming on at all either. Water temp is 178* by scan gauge which is what it runs pretty much at normal driving. Since the new aluminium radaitor installed last summer. The fans normally come on at 190* per the ECU.
My friend ask me why they where not coming on when the AC was on and I told him they come on from the ECU input. Which is only when the motor temp reaches 190, he said they need to be on anytime the ac is on which makes since.
So my question is, the 2 relays that run the fans are triggered by the ECU grounding them...right?
If so I want to hook them up to the clutch switch so it will ground them also whenever the AC is running.
Is this the right way to wire it?
Per this relay drawing?

[ls1nova71]

That would work, but you would be better off hooking the relay up to the switch that turns the A/C clutch on rather than at the clutch itself. You want to tie it in before the high and low pressure switches otherwise when it cycles, the fan will too which you dont want. The downside to it is the fans will run anytime the A/C is on which means running down the highway they will still be on even though they wouldn't be needed then. Shouldn't really hurt anything though, just might shorten the fan life a bit.

[Andy4639]

Originally Posted by ls1nova71

That would work, but you would be better off hooking the relay up to the switch that turns the A/C clutch on rather than at the clutch itself. You want to tie it in before the high and low pressure switches otherwise when it cycles, the fan will too which you dont want. The downside to it is the fans will run anytime the A/C is on which means running down the highway they will still be on even though they wouldn't be needed then. Shouldn't really hurt anything though, just might shorten the fan life a bit.

I will check the tie in spot and make sure it's before the low pressure switch. Thanks ls1nova71 again you come to my rescue!
Yes I thought of this also to be true while going down the road.
I'm thinking about if I just tie one in to the AC and leave the other one alone. Do you think it would be enough to keep the condenser happy while at stop lights and idling? I did some more reading and found out 2600 CFM is min for electric fans to keep the condenser happy so both will have to be on when the AC is on.
I don't think the water temp will be a issue since they don't kick on now until around 185* according to the description.

Here is the fan kit.
PRODUCT DESCRIPTION:
Dual Fan kit, 82-02 Dual Fan Kit 12" Fans 3,100 CFM, This is a universal dual fan kit for pretty much all 82-02 f-bodies. it comes with (2) 12" fans with 225 watt heavy duty fan motors that produce 3,100 CFM, it also comes with a wiring harness, 185 degree temperature switch, and a nylon tie kit to attach it to your radiator. Mine has been hard mounted.

Deminsions:
26" wide x 15" tall
Flows 3,100 CFM
3.94" Depth
26.6 Amp Draw

[clemsonteg]

I have 1 of my 2 fans wired like your first post. Mine put out 2000 CFM each, so I will see how it performs this summer and then decide if I should make changes

[ls1nova71]

Really the only time any of this is going to come into play is when the engine is cold, which in the summer isn't very long! If your engine cooling fans come on at 185, odds are they will never go off as long as the A/C is running, so only having one fan wired on with the A/C should be good enough to keep the head pressure at a safe level until the engine warms up and the fans come on.

[Andy4639]

Well I wired both of them in to the clutch relay for now. They where both already tied together so it was the easy way to do it.
Fans are wired like the relay schematic off LS1 page I posted above. Sitting in the garage in park the AC will blow 45-50* AC out the vents. This is just at idle speed.

Gauge readings low side 30-35, high side is 200-225 which I was thinking is a little low still, it's about 84* outside according to my temp in the front of the truck. The prob is mounted in the front grille area a way from the heat of the motor.
Going to go drive it and see how it does on the road. I'll post back later this afternoon.

[Andy4639]

Drove the truck over to my buddies shop and had him look at the pictures with the gauge readings and the temp readings. He said leave it alone for now and see how it does.
20 miles round trip and it stayed at 45* at the center vent even at the red lights. Temp never climb like it was before. I think it's good. I still have some holes on the fire wall to plug up but that should do it for now.

[dec010974]

Hello Andy4639. One idea that no one thought of b4 you made the changes to your fan electrical wiring was to add a pusher fan to the condenser. the fans mounted to the radiator would be wired as pullers. Look closely at the pics of the grill. so in total you will have three fans. good luck. Damn I miss this truck.

[dec010974]

take a look.

[Andy4639]

Originally Posted by dec010974

take a look.

Yes I have a old fan that I disconnected back when the LS went in. I may hook it back up also.
With the old radiator the fans came on and never had a issue. Now that the new radiator is more efficient it doesn't get that hot so they don't come on as much.

[clemsonteg]

Does the way you have it wired now only kick the fan on when the clutch engages, or all of the time while the AC is running?

[Custom 68]

I just have a single fan on mine. I added a switch so I can manually turn it on when I have my ac on and am at a stop or slow traffic. Probably not the best way because my switch has 3 positions, one is on when switched, the middle is completely off and the last is computer controlled. I don't feel the need to run it when going down the highway at speed when the engine is cool and the AC is on, maybe that is wrong and I would always benefit from it. When at shows or the power tour or just lots of traffic I can turn mine on in anticipation of it getting hot to get a head of it so to speak. I may change things around but right now it works for me. It is usually on the "automatic" side.
I don't know if the computer can compensate for speed and AC on I have not dug into that. I do know that when the AC is on it sends a signal to the computer this bumps up my idle some but don't know that it does much else.

[Andy4639]

Originally Posted by clemsonteg

Does the way you have it wired now only kick the fan on when the clutch engages, or all of the time while the AC is running?

Right now it will still come on if the water temp reaches 185-190 and the AC is off.
If the ac is on they run all the time.

Dave: I could add a manual switch to the clutch wire I guess if I needed to.
I don't really need them running while driving but just don't feel good about swapping back and forth.

[clemsonteg]

Originally Posted by Andy4639

Right now it will still come on if the water temp reaches 185-190 and the AC is off.
If the ac is on they run all the time.

Dave: I could add a manual switch to the clutch wire I guess if I needed to.
I don't really need them running while driving but just don't feel good about swapping back and forth.

Thanks. I haven't tested mine yet, I have the relay tied into the pressure switch before it goes to Ac clutch. I plan to look into the wiring to see if there is a better source.

[Andy4639]

Originally Posted by clemsonteg

Thanks. I haven't tested mine yet, I have the relay tied into the pressure switch before it goes to Ac clutch. I plan to look into the wiring to see if there is a better source.

Mine are wired to the ECU with it being a ground that turns them on. The relays have 12 volts to them all the time.

So by adding the extra relay that grounds them also it doesn't borther the ECU hook up.

[clemsonteg]

Originally Posted by Andy4639

Mine are wired to the ECU with it being a ground that turns them on. The relays have 12 volts to them all the time.

So by adding the extra relay that grounds them also it doesn't borther the ECU hook up.

That's how mine is hooked up as well. 2 grounds from the ecu control each of the fans and I have a 3rd relay that used the 12v from the clutch to supply a ground to the fan that activates at the higher temperature. So when my low temp fan is running the high temp fan will run with the AC. I'll have to test it because I think the fan will cycle with the AC and I'm not sure if that will be enough. I'd rather it stay on all the time when the AC is on in the cab not just when the compressor is cycling.

[Andy4639]

Originally Posted by clemsonteg

That's how mine is hooked up as well. 2 grounds from the ecu control each of the fans and I have a 3rd relay that used the 12v from the clutch to supply a ground to the fan that activates at the higher temperature. So when my low temp fan is running the high temp fan will run with the AC. I'll have to test it because I think the fan will cycle with the AC and I'm not sure if that will be enough. I'd rather it stay on all the time when the AC is on in the cab not just when the compressor is cycling.

Yea I did mine this way and had to change it out to the lead going to the low pressure switch on the accumulator. It runs them all the time now no cycling.
I'm going to do some investigating and see if there is a way to have it cut off at speed to keep from having them on all the time.
I found this. Not sure I want to mess with it though!

http://www.painlessperformance.com/Manuals/30140.pdf

[Andy4639]

Here is some more reading on the subject. I like this one but hate the price tag!


http://www.painlessperformance.com/webcat/30142

[Andy4639]

I have been looking all day on the net about electric fans and how to run them with the AC on and not one article talks about it except the Dakota and Painless mod that is $270.00!
The Dakota one want let it turn back off once it's turned on though.
Nobody has come up with anything that I can find.

[ls1nova71]

You could always use a trinary switch, but that would require breaking the system open to mount in a line. Using a trinary switch would only allow the fans come on when head pressure is high enough to need the fan, running down the highway the pressure would be low enough that the fans wouldn't be needed and therefore the fans would shut off.

Also, make sure you're pulling as much air through the condenser and not around it by blocking off any open spaces between the condenser and core support/radiator. This is what I did to mine.

[clemsonteg]

Since my system isn't charged yet, I'm going to swap my binary switch for a trinary switch. I also plan to wire the fans so they run together with the AC, but they will still run independently using the temps in the PCM. This is what I'm thinking at the moment, all of the triggers are grounds so I'll use a diode to keep the low temp PCM ground from activating the high temp fan

[Andy4639]

I looked at the trinary switch yesterday but as stated don't want to open up the system unless I have to.
What I did today also before the cruise stuff showed up. I took the relay's back a part and now have one fan only running with the AC on at all times.
Both fans will still come on with the PCM if the AC is not on.


Riding over to the little cruise in this morning it was 75* out and the temp never got over 178* in the motor the fans never came on. No AC.

Driving home it was 82* and I ran the AC the whole way home the motor temp never got past 178* except when I pulled into the garage and let it sit running for a few minutes with the AC off before I turned it off. They kicked on at 188*according to my scan gauge 2 reader right before I cut it off.
Thinking about maybe putting a hotter thermostat in it to get it up to a better operating temp.

[Andy4639]

Ok guy's I have been searching for a answer to my fans running all the time when I'm on the road at speed. We all know that these fans are expensive and burning up $300.00 fans isn't going to be fun no matter when they go out, so I finally think I have it figured out. I ran out of time so I'm going to test drive it tomorrow after work and see.
I even came up with a little light to tell me if it's working are not. I don't know if I'll keep it in the truck are not we will see. Really depends on how bright it is when it's on.
Ok here is what I did:
I wired a micro switch into the AC on wire to the relay I added a few weeks ago. Like in the picture with the arm extended with a flap on it to catch the air and turn off the fans once it see's enough air flow. I have it mounted inside the grill. Hopefully it has enough wind when driving it to shut off. I bolted it in place and put my fan in the front of the truck and it shut off so I hope it works.







I wired the small light on the back side of the switch so when the fans are on the light is to this way I know when they kick off at what speed.
When I know it works I'll post pictures of mine. They still come on at temp also.

[Big Port Jimmy 6]

My PCM requests the low speed fan with the AC clutch. I have a separate factory pusher fan wired to the AC clutch. Both cycle. I am using the 2 speed mark 8 fan and stock thermostat so mine is 200+in traffic, but that's no sweat for the 5.3 and the high speed rarely comes on, has to be really heavy traffic and 95+ outside. Do you have the AC input wired in? mine goes to c2 pin 17 (99-02 truck) Jay

[Andy4639]

Originally Posted by Big Port Jimmy 6

My PCM requests the low speed fan with the AC clutch. I have a separate factory pusher fan wired to the AC clutch. Both cycle. I am using the 2 speed mark 8 fan and stock thermostat so mine is 200+in traffic, but that's no sweat for the 5.3 and the high speed rarely comes on, has to be really heavy traffic and 95+ outside. Do you have the AC input wired in? mine goes to c2 pin 17 (99-02 truck) Jay

Mine is done. The paddle switch will turn them off @20-25 MPH and then back on. I just test drove it. I even installed a small light on the dash to LMK when they are ON/OFF!

I still have the temp controll also by the PCM @185* on! I have never seen the temp over 197*.