Fan Clutch still being a pain even after replacing it. [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Fan Clutch still being a pain even after replacing it.


Jay2003envoy
09-23-2010, 03:55 PM
Hello all I replace my fan cluth because it gets really loud at times. Well I replace it and it still gets loud. I notice now that it happens after I turn on my A/C most of the time that is. The car does not heat up thou. Does anybody have any idea what part I should replace? I have a OEM brand new fan clutch install about a month ago. Can anybody help me out.
Thank you.
2003 envoy
4.2l

KNBlazer
09-23-2010, 03:58 PM
it's a good thing I do believe when your fan clutch engages while the A/C is on... some peeps have trouble with their AC units when ambient temperature exceeds 90 degrees, the temp gauge starts creeping up, especially in traffic... but if it's of concern you could get your PCM flashed with the updated parameters which should alleviate your noise concerns.....

ylab
09-23-2010, 04:22 PM
GM did issue an updated firmware for models prior to I believe '05. That firmwware though was issued to improve a/c performance and actually runs the fan a bit faster than the original tuning did, when the a/c is turned on. Has your PCM ever been updated? (Particulary since late 2004 or early 2005). It's a catch 22 with the new code, it fixed the complaints about poor a/c performance in hot humid weather, but at the cost of slightly elevated fan speeds/sound.

If it has, a slightly elevated fan speed with a/c is normal. - It should not however sound like the 'jet-engine' affect you get when the clutch begins to fail. How loud is the fan with the a/c turned on? Also, who did the install? (If it was the dealer, there's a good chance they updated the PCM to better accomodate the new part).

If the PCM wasn't updated or you are sounding like a jet engine, it is possible that the new clutch is defective. Do you know if the part number was the new part and not one of the older/orginal part numbers floating around. (They're just old stock, the old part isn't in production any longer).

Jay2003envoy
09-23-2010, 04:43 PM
To be honest the fan clutch noise has not change after replacing the fan cluth part #25790869 I do believe it is BEHR manufactor. The noise starts after I turn on the A/C and step on the gas pedal. I don't know if the PCM has ever been updated. I really don't know what a PCM is. Like I said the envoy does NOT over heat. What part should I replace?
Oh, the heater does not work just the A/C.

Thanks

greeneyerocker
09-23-2010, 04:55 PM
I'm not sure why the vehicle is making a loud noise. I would suggest getting the wiring checked. The company that installed mine couldn't figure out why it wasn't working properly. Then they found the harness ahd not been plugged in and it worked fine. Ever since I've had it installed I have been havig a/c problems. The RPM's do not pick up whenever the a/c goes on so I get bad idling problems. I think I need to have the PCM flashed. Not sure.

Jay2003envoy
09-23-2010, 05:07 PM
I am wondering if a sensor has stop working. I think the fan goes back to normal at around 30 to 40 MPH or when I turn off the A/C.

ylab
09-23-2010, 05:20 PM
I'd be willing to bet your idling problems are a result of a dirty throtle body. They most likely disconnected the battery and the PCM is having difficulting adjusting to the slow response of the gummed up throttle plate. There's a sticky on cleaning them if you're not familiar with the process.

I'm not sure why the vehicle is making a loud noise. I would suggest getting the wiring checked. The company that installed mine couldn't figure out why it wasn't working properly. Then they found the harness ahd not been plugged in and it worked fine. Ever since I've had it installed I have been havig a/c problems. The RPM's do not pick up whenever the a/c goes on so I get bad idling problems. I think I need to have the PCM flashed. Not sure.

ylab
09-23-2010, 05:29 PM
That's the newest GM part number for the fan clutch, so made by Behr or not, it would appear to be a GM part. You only mention 'the noise', what is the noise? (Is it fan roar, clicking, clanking, knocking, etc). If the fan turns faster than the PCM (computer) commands, it should set a trouble code and turn on the CEL (Check Engline Light) if its spins faster/slower than a specified range. The '08+ vehicles may not set a code, since they don't have the feedback circuit, but '02 through '07 should.

To be honest the fan clutch noise has not change after replacing the fan cluth part #25790869 I do believe it is BEHR manufactor. The noise starts after I turn on the A/C and step on the gas pedal. I don't know if the PCM has ever been updated. I really don't know what a PCM is. Like I said the envoy does NOT over heat. What part should I replace?
Oh, the heater does not work just the A/C.

Thanks

Jay2003envoy
09-23-2010, 05:39 PM
The noise sounds like a jet it affects the speed in other words the faster I go the lounder it gets the slower I go the noise goes away. I feels like it affects the transmission because it does not let it switch gears. It goes away after I turn off the A/C or at around 40 MPH.

Jay2003envoy
09-25-2010, 10:47 AM
Why does turning on the A/C make the fan clutch get louder also gets loud when I step on the gas pedal. It seems to go away after I reach speeds of 30 to 40 mph and when I slow down and when I turn off the A/C I don't hear it anymore. Does anybody have any idea which part is damage?
Thanks

greeneyerocker
09-26-2010, 06:03 PM
The noise sounds like a jet it affects the speed in other words the faster I go the lounder it gets the slower I go the noise goes away. I feels like it affects the transmission because it does not let it switch gears. It goes away after I turn off the A/C or at around 40 MPH.

I thought the same thing happened to mine. Thought the a/c was bad. Someone told me to open hood start TB and then turn it off, if fan keeps turning the clutch is good. If fan stops when motor stops, then the clutch is bad. I replaced mine and now the noise went away. Going to clean my throttle body in a few minutes, hopefully that helps the idling problem. Only time my idle is bad is when the a/c kicks on. other than that the idle is fine. good thing weather is getting cooler down here.

Peter L
09-26-2010, 07:22 PM
I had a similar problem last spring. It turned out to be the water pump bearings.
Try to move your fan shaft up, down, side ways, if there is any movement,then you will have to replace the water pump. It sounds exactly like my problem, I even thought it was a tranny shift issue, but it was a water pump bearing.:crazy:
Hope this helps

BUC NASTY
09-26-2010, 07:45 PM
After swapping my my efans back to oem clutch, the oem clutch brang back ROARING memories.

Regardless if you get a tune update or replace the clutch you will still get the ROOARRR.

greeneyerocker
09-26-2010, 08:21 PM
I'd be willing to bet your idling problems are a result of a dirty throtle body. They most likely disconnected the battery and the PCM is having difficulting adjusting to the slow response of the gummed up throttle plate. There's a sticky on cleaning them if you're not familiar with the process.
Throttle body is clean as a whistle now front and back, problem still exists. I'm still leaning on a faulty fan clutch. It's under warranty but the labor isn't :( Looks like I'll be doing it myself this time. I've got the rental tools and 90 days before I have to return them :)

palafoja
10-06-2010, 09:32 PM
after tha clutch has been replaced you gotta give it time to disengage and than it will work normally, and the reflasing to the PCM is not necesary if the clicking sound from the fan when it cycles doesn't bother you other wise your fan your clutch and everything else will be fine.

BTW if you have a lot of miles on your engine you might want to spend a little more money on a water pump so you don't have to do the same work later on when the pump fails:m2: