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2005 gmc envoy_sle
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Discussion Starter · #1 ·
Of course I already know about the fan clutches, just need to know where to get one except from dealer. They now cost $455. They were only around $200 a year or so ago.
My story is 1st one went out like normal. 2nd went bad due to water pump failure and 3rd bought off ebay......it just plain ole sucks.
How much is the conversion to E-fans? Is is there a cheap enough place to order an OEM from?
 

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2003 gmc envoy_sle
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Just ordered a Dorman from Rockauto.com and it was shipped the same day. Got it on my door step in two more days. 147.29 shipped! WOW. Changed it out in a matter of a couple hours and everything is good to go.
 

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2002 gmc envoy_slt
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Dorman Fan Clutch

Question for you guys,

I just replaced my fan clutch on 2002 Envoy with a Dorman from Rock Auto. I called the dealership to ask them a question and they said that the software had to be updated when a new fan clutch was installed. He said it may not be operating correctly. The airplane whine has went away, but the temp is climbing to about 230 on an incline or on a hot day. He also said that some of the new fan clutches won't take a software update... I'm a bit confused.

Do I need to take the Envoy to get the software updated, or not?
Thanks for your help.... Barry
 

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Discussion Starter · #8 ·
I do think that I have read on here that some of the earlier models need the update for the fan clutch. Haven't heard if certain clutches will not take the updadte though. I would have the update done. Especially since you are running hot. That heat WILL cause early breakdown of oil and will reduce the life of the engine. Isn't the update a recall and done for free?
 

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Isn't the update a recall and done for free?
No.
I called the dealership to ask them a question and they said that the software had to be updated when a new fan clutch was installed. He said it may not be operating correctly.
Best information we have is that the software update is NOT necessary for the new style fan clutches to work in spec under all conditions. The software update addresses ONE part of the operation only, which is initial cabin cool-down when the engine is started and idling. The engine isn't needing any extra fan airflow because it isn't warmed up yet, BUT that's exactly when the cabin is the hottest and the AC is trying to cool it down but the engine is idling so the fan speed it at its lowest. The software update boosts the commanded fan speed under those conditions to maximize AC performance even if the engine doesn't need it.
The airplane whine has went away, but the temp is climbing to about 230 on an incline or on a hot day.
This is bad, and not caused by the fan clutch. Might be thermostat not opening fully, clogged cat, or any of a dozen other things. You should get a high-end scan tool looking at the vehicle when you're overheating to see exactly what the commanded fan RPM is compared to the actual fan RPM. Call independent GM specialist mechanics to find one who can do that without being blinded by false folklore like your dealer is.
He also said that some of the new fan clutches won't take a software update...
Nonsense. The software goes into the PCM, not the fan. If the replacement fan won't spin at the commanded RPM, the PCM will eventually set a code. But the software isn't loaded into the fan. The Korean aftermarket fans have a bad reputation now for copying an intermediate version of the fan design, and we assume Dorman and the others are now clones of the proper latest generation clutch design. A fan that won't obey the PCM's commands is bad, and the only real way to tell is to drive around while watching the data stream with scan software.

Bottom line: the software update is worth paying for if you are in a climate that demands fast cool-down on start-up. For normal road operation, it will not help an overheating problem. Above 30-35 MPH (?), airflow is more dependent on vehicle speed than fan RPM anyway, so if you're seeing 230 temp driving on a freeway incline, you have a different problem to troubleshoot.
 

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Similar problem, 03 TB EXT 4x4

I'm having a similar problem with my 03 TB Ext. My problem is, the fan simply NEVER turns on when the car is moving. I've let it go as high as just over 3/4's on the temp before giving up. Monitoring the commanded fan speed, it never goes beyond 10%. GM is useless on this issue, and I've had them reprogram (and then replace cause it died in programming the first time) the PCM to what they say is the latest release, and no change is evident (although it did get rid of an odd hesitation when using light gas pedal touches)
I'm at wits end with this, and am about fed up with the engine running hot particularly when the AC is on. as such, I have rigged up a manual toggle which simply turns the fan on 100%, as it in essence shorts the 2 pins that give the fan the pulsewidth.
Also, any one have a 2008 or 2009? Seems they've eliminated the electronic clutch fan altogether on those (I dont quite get why they'd screw with something so simple that just works any way)
if ANY one has any insight to how I can fix my problem beyond this toggle switch I'm open to suggestions. (Btw, my local GM dealer maintains that if its not in the red, its doing just fine. A retarded statement given that Red indicates 260, not a healthy temp for aluminum engines.)
 

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It's kind of unsettling that Dorman views our platform as some kind of cash cow.:worried: That and the fact they think our trucks are based on the s10 and s15 platforms! Makes you wonder how much knowledge they really have about our vehicles! :confused:
 

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It's kind of unsettling that Dorman views our platform as some kind of cash cow.
Not really. When the aftermarket gets involved in offering replacement parts, they should do it with knowledge of why the OEMs fail so often. They don't want the cost of warranty exchange of the replacement ones. And it always drives prices down to have multiple sources. I think we win.

Monitoring the commanded fan speed, it never goes beyond 10%.
This is such a unique problem, but the cause looks like it should be localized. If the PCM output transistor was dead, the PCM should be trying to command 100% fan RPM and it would never get there. If the PCM is only commanding 10%, and it's running according to programming, I'd guess its input values were wrong. Like ECT. But that would mean the gauge value would be ultra-low, so I don't get it. When they were monitoring the data stream, did you (or they) see anything odd about the ECT value?
 

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Here's my fan clutch story- very intermitant noise for a while, gradaully got to be very annoying, so I changed it with a Dorman unit. No longer intermitant, 100% all the time. Took it GM for the reprogram, no change. Peeled back the plastic conduit on wiring harness, very suspcious kink in gray wire. Have tried to bypass this and see if I get a good result, so far no luck. I leave the thing disconnected so I don't have to listen to it. No side effects - temp steady at 210, AC good, MPG bad but that's normal, right? Haven't been towing anything though - Do I really need this thing?
 

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I've been having similar problems. My engine was making that rushing/whiring sound for a few days, then over heated one day. I pulled over and let it cool down, limped it home and when I started it next time it ran just fine. About a week later I overheated again. I pulled over and let it rest. Once I re-started it; nothing seemed to be the matter. I can't figure it out. The code that showed up pointed toward the fan clutch being bad or a wire short/bad connection. It said that the output from the PCM was not consistent with the fan speed sensor reading.

Since then I've been getting less than 14 Mpg when i normally get over 16. no codes have come up lately, but I'm certainly sick of this bad gas miliage. Especially with a 6 cylinder. Plus I don't want to have to wonder when i'm going to overheat next. I live in TX and summer is coming. Any ideas on what to do to fix my problem?
Peter
 

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I've been having similar problems. My engine was making that rushing/whiring sound for a few days, then over heated one day. I pulled over and let it cool down, limped it home and when I started it next time it ran just fine. About a week later I overheated again. I pulled over and let it rest. Once I re-started it; nothing seemed to be the matter. I can't figure it out. The code that showed up pointed toward the fan clutch being bad or a wire short/bad connection. It said that the output from the PCM was not consistent with the fan speed sensor reading.

Since then I've been getting less than 14 Mpg when i normally get over 16. no codes have come up lately, but I'm certainly sick of this bad gas miliage. Especially with a 6 cylinder. Plus I don't want to have to wonder when i'm going to overheat next. I live in TX and summer is coming. Any ideas on what to do to fix my problem?
Peter

Have you changed the F/C? If so. Change the T-stat also. I changed both and works well now..
 

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Best information we have is that the software update is NOT necessary for the new style fan clutches to work in spec under all conditions. The software update addresses ONE part of the operation only, which is initial cabin cool-down when the engine is started and idling. The engine isn't needing any extra fan airflow because it isn't warmed up yet, BUT that's exactly when the cabin is the hottest and the AC is trying to cool it down but the engine is idling so the fan speed it at its lowest. The software update boosts the commanded fan speed under those conditions to maximize AC performance even if the engine doesn't need it.
Does this software update boost the fan speed in all idling conditions, or only immediately after ignition?
 

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Does this software update boost the fan speed in all idling conditions, or only immediately after ignition?
We're not sure, but I would have coded it to boost the fan speed any time the engine is idling, doesn't need extra cooling for the engine, but the AC is on and it needs more airflow over the condenser. Is the answer critical to anything you're observing?

I could look at the commanded fan RPM versus ECT performance with my scan software sometime and see if I can deduce the details.
 

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difficulty

I have not changed the fan clutch yet, but I tried changing the thermostat... WHAT A PAIN! i'm going to look and see if there are any other instructions on here for getting that done. I had the most difficult time getting to that bottom bolt. Pep boys wanted $102 just for the labor. I'm hoping I can get to it after looking for instructions. If anyone knows of any instructions, post a link for me will you...
thanks

Have you changed the F/C? If so. Change the T-stat also. I changed both and works well now..
 
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