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Discussion Starter · #1 · (Edited)
So anyone who has ever dealt with a stock LT1 knows they tend to run hot. In hot southern climates it makes our vehicle prone to over heating rather easily.

Well, my 95 Z28 sprung a tiny little leak from one of the seals on the passenger side steam pipe. Yay! I replaced the seal, but in the process I also installed a new fan control module.

I bought it at Oreilly's Auto for $35. I figured instead of running a switch for manual over ride I'll just replace the stock control (via PCM) with an adjustable version available after market. I have one of these installed in my Suburban (have had it installed for over 3 years and I know it works good).

I didn't have to cut a single wire either. So this is how I did it. I'll try and get some pics later.

First I connected the control module power wire straight to the battery. Then the ground wire to the frame next to the upper radiator support on the drivers side.

I tapped into the A/C over ride power via the A/C fuse in the fuse box. And the ignition power wire got tapped into the ABS ign source via fuse in the fuse box too.

Next I installed the temp sensor to the radiator near the radiator return hose on the drivers side. This is a pain in the butt because of how much (read: little) clearance there is between the A/C radiator thing (condenser?) and the radiator it's self. It comes with a mounting thing for it too in the kit. Be very very careful when installing this because it sits in the fins of the radiator. You'll need to bend a couple fins out of the way, so make sure you only move what is necessary and what will actually move with only hand force. No tools to force this through!

I then removed the three fan relays. I jumped J4 to J1 on relay three (thanks ShoeBox for the schematic via your website shbox.com !!!!). This is only necessary on F-Body's with 3 relays.

The controller I bought comes with 2 fan control outputs. So I connected one (the blue wire) fan output to F1 for fan relay 2 and the other fan output (orange) to fan relay 1 D4. See schematic below for reference.



All my connections to existing wires are connected through to terminals in the fuse box. It looks a little ghetto, but works like a champ.

At idle with the A/C on the temps don't go past 185 degrees on the dash gauge. With the A/C off the temps climb to about 200 before the fans kick on then cool down to about 190 before they cut off again. This is with an ambient temp of 96* outside.

I'll post up some results after a few days driving in stop and go traffic at triple digit temps. So in a few days, lol. Once I'm comfortable with this set up I'll clean the wires up a bit and post some pics.

I didn't have to cut into any existing wires to make this work, nor did I drill any holes in my dash. Plus I don't have to worry about forgetting to turn it on or off. And now my car runs much much cooler. I also installed a 160* thermostat recently too.

I thought I'd post this for those interested. The part I bought was available at Oreilly's Auto parts (CSK Auto I think) and was locally stocked. Part Number 3647 by Hayden.
 

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the only downside to doing it this way (instead of a tune) is that the fans can actually impede airflow at higher speeds when the air dam is functional -- that's why the pcm has different settings for high and low vehicle speed.
 

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Can you post a pic of the sensor and how it sits in the radiator? I just wired mine to run all the time, but this sounds pretty cool. Is it adjustable?
 

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Seems like a lot of work for what could have just been tuned through the PCM.
It is, but I guess if you don't have a way to change the tune, it is an alternative. The PCM retune is much better and allows the fans to shut off at speed as was previously mentioned and is the most worry free way.
 

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Discussion Starter · #7 ·
the only downside to doing it this way (instead of a tune) is that the fans can actually impede airflow at higher speeds when the air dam is functional -- that's why the pcm has different settings for high and low vehicle speed.
Not true. The fans become an impediment with their existence at higher speeds regardless of tune, as long as the airflow through the radiator is greater than the airflow the fans are making.

My fans, with this mod, come on at "high" setting at ~200*, then turn off at ~190*. The factory settings have the fans come on at low speed at a higher temp of 226*, and high speed at about 240*. I have no low setting.

At highway speeds my engine temps would stay below the mid mark of the dash temp gauge (so less than 210*). This means the fans would never turn on (this is when I had the 180* thermostat). With ram air being forced through the radiator and no power to the fans the fans become a restriction. This is stock mind you.

However, the resistance the fans provide are far less than the added drag they put on the motor while they are running off the alternator.

With my adjustment setting and my cooler thermostat (160*) I end up with high fan settings only that kick on at ~200*. This means if they do come on at highway speed, they'll actually create less resistance than if they were off. But because at those high speeds my engine will be cooler than the 200* (I've been seeing about ~175-180* when highway cruising), my fans won't come on and they'll be just like the stock set up.

The only issue I have is the A/C override causes both fans to come on at high speed all the time (similar to stock, but stock is low speed then kicks to high at 240*). This is a reduction of fuel economy and power, but that's to be expected with the A/C on. But with the A/C on the car doesn't get over 185*.
 

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Discussion Starter · #8 ·
Seems like a lot of work for what could have just been tuned through the PCM.
I wan't going to spend the money to have my car tuned before I was ready for it. Because nothing was cut or spliced I can still have it tuned by the PCM and just plug the relays back in and remove the stand alone controller. No fuss.

Tuning my computer would've cost me more than this and taken longer (OBDI with 16 pin). when I do my rebuild I'll do the tune. For now this'll do.
 

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Discussion Starter · #9 ·
It is, but I guess if you don't have a way to change the tune, it is an alternative. The PCM retune is much better and allows the fans to shut off at speed as was previously mentioned and is the most worry free way.
Right. That's what this is. It's cheaper than a tune too.

This also allows the fans to turn off at speed. But the whole "restriction" thinking is wrong. The fans being on become less restrictive than with them off. You want them off while at highway speed for fuel economy, which is also moot with the A/C on because the fans run all the time.
 

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But the whole "restriction" thinking is wrong. The fans being on become less restrictive than with them off.
my previous tests with a manual fan switch have shown otherwise -- disabling the fans at highway speed did drop coolant temp. others have found the same

it's probably not enough where you'd care about it, so dont stress it.
 

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Discussion Starter · #12 ·
my previous tests with a manual fan switch have shown otherwise -- disabling the fans at highway speed did drop coolant temp. others have found the same

it's probably not enough where you'd care about it, so dont stress it.
The fans DO disable at highway speeds, but only if the A/C is off. This is the same setting as stock vehicles BTW.
 

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Discussion Starter · #13 ·
From what I've read, I thought most guys racing have them run on high? Maybe I'm wrong though and they let them freewheel. I'm sure Dave has done both and know's which is the way to go.
When I'm racing I expect them to be on high too. I could care less about F/E. I want them cooling my engine down. You really think about it and more often than not while you are racing your car isn't moving that fast. 1/4 mile racign you spend more time in the pit and staging lanes than at 100mph (which even then is only for a second or two). Street (road course) racing has you doing less than 75mph on most tracks for average speed and that's if your fast. But if your driving it hard temps rise and the fans kick on anyway. Mine just come on harder and sooner.
 

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Discussion Starter · #14 ·
Can you post a pic of the sensor and how it sits in the radiator? I just wired mine to run all the time, but this sounds pretty cool. Is it adjustable?
Here's the sensor in the radiator.




And here's the fuse box and how I hooked it all up.

The black wire is the jumper for J4 to J1 on relay 3.

The green wire is the A/C override I am running off of the A/C Relay, terminal B4.

The blue an orange wires get plugged up to relay's 1 and 2 terminals F1 and D4. One to each. It doesn't matter which ones go to which.

The yellow wire is tapped into the ABS ignition fuse.



Here's the controller.



And what it all looks like put together.

 

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Discussion Starter · #15 ·
Hats off for being creative and thinking outside the box though.
Thanks. This allowed me to "tune my fans" to come on sooner without cutting into the existing wires, only cost me $35 (well $38 after taxes), and I don't have to worry about forgetting to turn them on or off.
 

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Discussion Starter · #17 · (Edited)
That is not correct. The fans will cease with the a/c on.
Thanks for the correction. I cannot find anything to confirm or refute your claim, so I will assume you are correct (I'm not being sarcastic here).

In any case this is exactly how my Suburban is set up and it cruises along in stop and go traffic with both A/C's blaring in 115* heat at ~200* all day and ~185* on the highway in the same weather. Of course the radiator in that thing is in a much better position.
 

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Discussion Starter · #19 ·
I can confirm it. I have fan status LEDs on my console that tell me when the fans are on and they will cut off at speed even with the a/c on.
Thanks. All the more reason to hook everything back up after I do the tune. But that'll have to wait until I finish my rebuild.

With my setup all I have to do is unplug my aftermarket stuff and put the relays back in.

Sent from AutoGuide.com Free App
 

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Hi, I just found your post while searching for a lower radiator airflow dam for my 96 Z28 Camaro that has a LT1 V8, we wired the fan to the ignition and I plan on replacing the deco hood vents soon and there is a discussion of removing the internal thermostat for the summer here in Tennessee, but cannot find any lower airflow vent/damn. Any suggestions would be helpful.
 
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