DBTKDT Posted October 16, 2010 Report Share Posted October 16, 2010 I had put a set of the oem 05 e-fans on my wifes 04 Denali a few years ago now. I was wondering who has done the same fans and what harness everyone is running? I had a company around me make a harness with better relays then other harnesses out there. The only problem is that when the ac kicks on these fans are screaming some crazy rpms and are very loud! When they both come on low speed from the pcm they sound like the high speed from the factory set on high. I have heard an 06 and you can hardly hear them on high. Does anyone make a good reliable harness that is more geared and set up like the oem set up? Just something I want to redo and be like the oem set up! Thank you for your input. Hope I can find something that works! Quote Link to comment Share on other sites More sharing options...
Bear Posted October 16, 2010 Report Share Posted October 16, 2010 Looking around a little, you will notice people referring to a dual pin harness. When people refer to a dual pin harness, what they are talking about is using the ECM to control both fans/speeds, instead of using only one pin in the ECM and tapping into the AC for the second pin, as it what was a common method for people retrofitting the fans into older models. While it is completely possible to convert to the dual pin method of activating your fans, you will need the computer re-programmed to do so, as the second pin is plugged into a pin that is normally defined as recirculate for the HVAC system in the trucks. By using this approach, you should notice you have softer starts for the fans and not as much voltage drop when they kick on. I can’t give you real life specifics, as I’m still using the older method for activating my fans and only passing on what I’ve heard. Maybe some of the other members can really nail down what you need to do to make the switch. Quote Link to comment Share on other sites More sharing options...
misterp Posted October 16, 2010 Report Share Posted October 16, 2010 The A/C control system in the pre-2003 trucks is completely different than the 2003+ trucks; because of this there are TWO different methods of wiring an efan control harness. The efans must be on when the A/C is running, or the refrigerant will overheat and then overpressurize and vent to the atmosphere. In the pre-2003 trucks the PCM only has the ability to switch efans "on" or "off" based on engine temperature; you have to make your own way of turning fans on when the A/C is running. In these trucks usually you have one trigger wire going into the PCM and another going to the A/C compressor clutch relay wire - that way if either circuit is activated, you get efans. If you are elaborate, you can make your harness go "low speed" or "single fan" when the A/C is on, and high-speed when the motor gets hot. If you want to completely avoid reprogramming the PCM, you can install another cooling sensor in the engine pre-set at 190-degrees, and have it trigger the efans. In the 2003-2004 trucks, the PCM is completely capable of fully controlling efans, it's just that since the trucks came from the factory with a clutch fan this programming is switched-off. If you make an efan control harness that has a low and high speed, you can tie your two trigger wires right into the PCM and then it will run the fans as it sees fit, because the 2003+ PCMs know exactly what is going on in the climate control system and can switch on the efans as it desires. The *great* thing about the 2003+ PCMs is that they will shut off the efans when you are driving 45-mph and faster, saving about .15-MPG (this is why GM put them on the 2005+ trucks, to meet Congressional fuel mileage standards). Your second question - fan noise: GM factory fans are made to be as quiet as possible -and- not pull too much current & overheat stock wiring, and in doing so they do not pull as much air as other brands because the fan blades have less pitch to them. And other brands (FAL) are noisy as hell and move even less air than the GM efans. The efans in my kits are factory equipment on Ferrari 599, and they have a 'commanding' sound and pull a dramatic amount of wind, and amperage (60-amps at full draw). ----- Without dissecting what you have - you sound like you have a control harness with two speeds (good) but you have the trigger leads reversed; you want the low-speed fans to turn on when the A/C clutch is engaged, and the high-speed fans to run when the engine gets hot; the behavior you describe is just the opposite. Mr. P. Quote Link to comment Share on other sites More sharing options...
03BlkSS86 Posted October 17, 2010 Report Share Posted October 17, 2010 Sorry not to hi jack his thread, but Mr. P are you still selling your efans kits? Quote Link to comment Share on other sites More sharing options...
DBTKDT Posted October 17, 2010 Author Report Share Posted October 17, 2010 The A/C control system in the pre-2003 trucks is completely different than the 2003+ trucks; because of this there are TWO different methods of wiring an efan control harness. The efans must be on when the A/C is running, or the refrigerant will overheat and then overpressurize and vent to the atmosphere. In the pre-2003 trucks the PCM only has the ability to switch efans "on" or "off" based on engine temperature; you have to make your own way of turning fans on when the A/C is running. In these trucks usually you have one trigger wire going into the PCM and another going to the A/C compressor clutch relay wire - that way if either circuit is activated, you get efans. If you are elaborate, you can make your harness go "low speed" or "single fan" when the A/C is on, and high-speed when the motor gets hot. If you want to completely avoid reprogramming the PCM, you can install another cooling sensor in the engine pre-set at 190-degrees, and have it trigger the efans. In the 2003-2004 trucks, the PCM is completely capable of fully controlling efans, it's just that since the trucks came from the factory with a clutch fan this programming is switched-off. If you make an efan control harness that has a low and high speed, you can tie your two trigger wires right into the PCM and then it will run the fans as it sees fit, because the 2003+ PCMs know exactly what is going on in the climate control system and can switch on the efans as it desires. The *great* thing about the 2003+ PCMs is that they will shut off the efans when you are driving 45-mph and faster, saving about .15-MPG (this is why GM put them on the 2005+ trucks, to meet Congressional fuel mileage standards). Your second question - fan noise: GM factory fans are made to be as quiet as possible -and- not pull too much current & overheat stock wiring, and in doing so they do not pull as much air as other brands because the fan blades have less pitch to them. And other brands (FAL) are noisy as hell and move even less air than the GM efans. The efans in my kits are factory equipment on Ferrari 599, and they have a 'commanding' sound and pull a dramatic amount of wind, and amperage (60-amps at full draw). ----- Without dissecting what you have - you sound like you have a control harness with two speeds (good) but you have the trigger leads reversed; you want the low-speed fans to turn on when the A/C clutch is engaged, and the high-speed fans to run when the engine gets hot; the behavior you describe is just the opposite. Mr. P. I have been trying to find out for the last two years and I could never get a straight or correct answer! That was stated so well and makes complete sense! Thank you for that infomation! I heard the factory fans and they are so nice and quite, thats why i went with the oem fans and they look complete factory like i never did anything. I will do some more homework and get things dialed in to be right. I also have a set of 05 e-fans for my 2003 1500 hd with the 6.0 and i'm trying to get a new harness done for that and fix the problem with the harness on the 04 Denali. Thanks again for the great feedback! I've been on many other truck forumsand have gotten no where on this topic! Great Forum!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
misterp Posted October 17, 2010 Report Share Posted October 17, 2010 ...Thank you for that infomation! ... Ask the guys, efans have become my thang lol. The GM fans are not bad, I would consider either them or my kit; the PRO's of the GM fans is that they are quiet, reasonable cost, and widely available (wrecking yards). The only thing to remember when buying a set of GM efans is that you also need to get the efan harness from the donor truck too, and GM looms it in the headlight harness so you have to take a few extra minutes and unravel that; most guys don't have the patience for that and it bites them in the azz in the end. Sorry not to hi jack his thread, but Mr. P are you still selling your efans kits? Yes, on group purchase only - tomorrow I am pricing components to set pricing for this fall's group purchase, stay tuned. Send me a PM and that way I will put you on my contact list and notify you when the GP terms are announced. Mr. P. Quote Link to comment Share on other sites More sharing options...
BLUESS2003 Posted October 25, 2010 Report Share Posted October 25, 2010 So for a 03 SS all I need is the OEM fans from a 05+ tahoe or silverado and the two pin wireharness and a PCM tuned on for the fans and i'm done?? COOL if so.. Quote Link to comment Share on other sites More sharing options...
Cramer Posted October 25, 2010 Report Share Posted October 25, 2010 You got it! Took me 30 min to do mine. Quote Link to comment Share on other sites More sharing options...
SmalltownSS Posted December 3, 2010 Report Share Posted December 3, 2010 I live in a small town in northern ontario, there is no waiting in traffic, and it isnt warm out for many days each year (over 70degrees) so cooling isnt and issue...... The irratating always running mechanical fan is though, takes a really long time to warm up when it is -15f and i do alot of hiway driving and i dont need that fan running all the time! From what i have read the stock 5.3l silverado fan would work the best for me, quiet, no need to replace alternator low cost etc. I need to know a few things. 1. what year and models have fans that will work with my 03 Silverado SS 2. What else do i need to make this work other than the fans, shroud and wiring harness from the 5.3 3.do i need a custom tune to get the fan to work properly with the truck Thanks guys gonna get this done this winter! Quote Link to comment Share on other sites More sharing options...
sdimedude Posted December 3, 2010 Report Share Posted December 3, 2010 That is weird. My factory fans are loud as crap when they are on high. Mine only go on high in the middle of the Summer. And that is only if I'm sitting in traffic for a while or if I just shut the motor off for a short amount of time and started it back up. Quote Link to comment Share on other sites More sharing options...
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