I installed E-fans on my 2001

[Rocket Man]

Shameless plug for those folks wanting to have the 1999-2002 trucks control the fans based on A/C system pressure just like the 2003+ ones do. https://www.tahoeyukonforum.com/threads/electric-fans-on-2002-1500hd-with-proper-a-c-control.106034/

Looks like a lot of work. What’s the advantage?

 

[bottomline2000]

Looks like a lot of work. What’s the advantage?

Without looking, better fan control..not always cycling on high with the compressor..they cycle high when the pressure hits a certain point.

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[Rocket Man]

Without looking, better fan control..not always cycling on high with the compressor..they cycle high when the pressure hits a certain point.

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I need mine to cycle high as much as possible. With my blower's big ass intercooler in front of the radiator, the condenser doesn't get enough airflow in stopped traffic on real hot days and the AC cyclrs off until I get moving again. I would prefer more fan, not less.

 

[bottomline2000]

I need mine to cycle high as much as possible. With my blower's big ass intercooler in front of the radiator, the condenser doesn't get enough airflow in stopped traffic on real hot days and the AC cyclrs off until I get moving again. I would prefer more fan, not less.

Well if the computer was looking at pressure instead of a switch it should run more depending on need. Remember u have that load boss alternator so make sure it's not lagging on amperage at idle. I had that problem and my fans would attempt to start and stop before completing a cycle. Basically the alternator needed more than idle rpm to put out enough amperage for the fans to operate properly. My DC Power alternator alternator behaves like stock only it put out a lot more idle amperage..

The question is are your fans cycling and the a.c. not working or are the fans just not able to run on high and just cycle off? If it's the 1st then the intercooler may be your problem. I'm concerned about this since I have a trucool 40k already in the way so I would hope the intercooler wouldn't cause a cooling problem.

Is it any better after putting in Scottys harness?

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[Rocket Man]

It seems the same after the harness, but the problem I think is the fan only comes on when the compressor does so when the system stops because the condenser isn’t working due to insufficient airflow, the fan stops too which only makes things worse and I have to drive at 34-40 for a couple minutes and the sc turns back on. Stupid 02’s. There is a tsb where they add another fan just for the condenser but I don’t have room for it. My voltage is fine.

 

[bottomline2000]

It seems the same after the harness, but the problem I think is the fan only comes on when the compressor does so when the system stops because the condenser isn’t working due to insufficient airflow, the fan stops too which only makes things worse and I have to drive at 34-40 for a couple minutes and the sc turns back on. Stupid 02’s. There is a tsb where they add another fan just for the condenser but I don’t have room for it. My voltage is fine.

Yeah, we're in the same boat. U would think it would be ez to convert to the 03+ setup. That write up makes my head hurt..luckily mine seems to work ok even in Triple digit weather. I'm sure it can be done but its going to take a lot of sending datalogs to Justin to get it right..I saw segment swap and I already have a segment swap for my trans..not ready to fight that battle again..

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[Mattn314]

How-To: Installing 06 E-fans on a 2001

This is a step by step tutorial on how to upgrade any 00-02 Tahoe, Yukon, or Suburban to the 05-06 GMT800 electric cooling fans. This same setup can be used on 03-04 trucks as well, however the only difference is the wiring that connects to the PCM. I will also add that a custom tune from someone like Blackbear Performance(who is a site sponsor by the way) is also needed, because the pins to control the fans in the PCM need to be turned on with the tuning software.

First of all, you need to measure your radiator to see what size it is. Some trucks came with a smaller radiator, (28 inches wide I think) and some have the larger radiator, which is 34 inches wide. The 05-06 Tahoe/Silverado electric fans can only be used if you have the larger radiator. So if you have the smaller one, you need to upgrade your radiator first. If you have the 34 inch radiator, like I do, the fans will bolt right up as if they were made for your truck. The holes for the fan to bolt on are already in the radiator support. It uses the same bolts as the radiator. So if you didn't get the bolts with your new fan, just go grab some radiator bolts off a truck in the junkyard. I got my fans from a 2006 Chevy Silverado in the junkyard. I was also able to pick apart the wiring harness and get that as well. I even got the pin that needs to be added to the PCM harness. So now I have an OEM wiring harness complete with fan relays. This actually clips right onto the side of your underhood fuse panel once you remove the cover. Here is the fans and the harness that I got.
View attachment 116805
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I cleaned up the harness and added some wire loom to it and made it look cleaner, for a cleaner install.
View attachment 116810
You can buy a pre-made harness from Blackbear Performance for a very easy install. Or if you are able to procure the correct pigtails for the fans and the PCM, you can custom make your own harness. Here is a wiring diagram of how the fans are factory wired on the 05-06 GM trucks.
View attachment 116811
If you have an 03-04 truck, then you will wire it exactly like this diagram shows. But on a 99-02, the PCM only has pin 42 available to use. The other trigger wire has to be connected to the AC compressor clutch relay wire. That wire is positive, so by me using an OEM harness, I had to add a relay to that wire to change it to a negative in order to trigger the fan relay pack, which is set up to be triggered by negative signals from the PCM. This extra relay is not needed if you use the pre-made harness from Blackbear. Thier harness is already setup to use a positive trigger from the AC wire. Now onto the wiring. First you want to remove your underhood fuse panel cover. Not just the lid, the entire cover. You will have to unbolt the corner fender brace in order to get it up and off. Now lift up the fuse junction block to get access to the underside. You will need to splice into the dark green AC clutch relay wire. This is the wire you need.
View attachment 116812
This is where you will tie in your relay (or trigger wire if using a Blackbear harness). The relay needs to be wired as follows:
86-Green AC wire
85-Ground
87-Ground
30-Blue trigger wire on OEM fan relay pack

And here is how your relay should look.
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Now take the green wire on your relay and splice it into the factory Green AC wire with solder and heat shrink tubing.
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I grounded the ground wire to this bolt on the fender, right below the fuse block.
View attachment 116819

What relay did u use for this, I'm going to be doing it soon

 

[Rocket Man]

What relay did u use for this, I'm going to be doing it soon

I highly recommend an OEM harness from a junkyard or even better, @ScottyBoy gets them, cleans and fixes them up and sells them. If he doesn’t chime in here, send him a private message. I went through 2 complete aftermarket harnesses and they kept melting. Once I was left stranded 100 miles from home in 100 degree heat because my truck overheated due to no fans and a melted relay pack. Since installing an OEM one, no issues at all.

 

[Staggered 02]

Nice write up. I dropped off my electric fans to get color matched before I flew out. This mod is on the list of things to do on the 02 Silverado. Thanks for the details.

 

[Mattn314]

I highly recommend an OEM harness from a junkyard or even better, @ScottyBoy gets them, cleans and fixes them up and sells them. If he doesn’t chime in here, send him a private message. I went through 2 complete aftermarket harnesses and they kept melting. Once I was left stranded 100 miles from home in 100 degree heat because my truck overheated due to no fans and a melted relay pack. Since installing an OEM one, no issues at all.

I have the OEM harness I have a 01 thi and it needs the extra relay