New fan clutch installed. Have a question

snoozer

Original poster
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May 15, 2017
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Over the weekend my fan clutch stuck on fully engaged & stayed that way.
After reading I have no idea how many topics on this, I had a repair shop that I use put a new one on & a new water pump while they were at it.
Picked it up from the shop & noticed that when I started it up the fan clutch revved up like it was fully engaged, but drove about a block & it quite down & could not get over the power t had now. Drove it home just about a mile, left it sit until next morning went out started it up & sounded like a jet taking off, rpm's were up to about 2000, then as rpms dropped the fan was getting quieter, so I took off I could still here the fan & reduced power for about 3 blocks or so, then it ran fine.
Stopped at store ran in for maybe 10 minutes at first when I started it, it was quite until I hit the gas to backup then it started being loud for just maybe a block then all quite down again.
When the fan isn't engaged full speed, jet engine a roaring it has quite a bit of get up an go.

This is on a 2003 Trailblazer LS, about 120,000 miles, I have only had it for about 6 months or so.
I am not sure what brand of clutch was put on.

Is this normal behavior?
The shop that installed it said it was normal. They told me to drive it for awhile & see what it does & if there is a problem they will take care of it.
I just wanted to get others opinion on this who owns a Trailblazer.

I used to do all my own repairs until health issues forced me to rely on others to do it.
After 20 plus years of owning an 89 Suburban this fancy stuff throws me off on how it works.

Thank you for bearing with a newbie here.
 
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Mooseman

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Dec 4, 2011
25,260
Ottawa, ON
Welcome to the Nation!

It's normal operation.
Reason for fan at startup?

Basically, as the silicone fluid will pool into the clutch, it will be engaged until the fluid heats up and returns to the reservoir. This video shows how it works (electro-viscous is basically the same except electrically instead of thermally controlled)

Although they don't mention it, the fluid will leak down into the shear plate overnight. Until it gets back into the reservoir, it will be engaged.
 

snoozer

Original poster
Member
May 15, 2017
45
Home
Welcome to the Nation!

It's normal operation.
Reason for fan at startup?

Basically, as the silicone fluid will pool into the clutch, it will be engaged until the fluid heats up and returns to the reservoir. This video shows how it works (electro-viscous is basically the same except electrically instead of thermally controlled)

Although they don't mention it, the fluid will leak down into the shear plate overnight. Until it gets back into the reservoir, it will be engaged.

Will it also do this when left to sit for an hour or so with engine up to operating temp?
 

hockeyman

Member
Aug 26, 2012
726
My '03 Envoy started doing this a month before I traded it in. Here's the thread on my "very similar" issue:
http://gmtnation.com/forums/threads/p1481-code.16402/#post-520818

Replaced the fan clutch, twice, still got the loud noise for about 1/2 mile of the startup and drive, then it would go silent and act normal. Even made the noise when starting and driving with and without a hot engine. "Florida-Hot", too.

My concern was that it literally started out of nowhere one day in November. The noise, since owning it, only happened on the initial startup (cold) and lasted about 50 ft. Then out of nowhere, it started to become much more often. Two different brands of brand new fan clutches did not fix it. Kept making the jet engine noise even after repairing the wires from the hungry squirrel.

I did not give it too much more of a chance after that. Got tired of worrying about the reliability of trips lasting longer than 10 miles and decided to trade it in. Although I sometimes regret it...
 
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Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
Will it also do this when left to sit for an hour or so with engine up to operating temp?

I supposed it could depending on which position the fan stops in. As long as it doesn't stay like that for a long time, I wouldn't worry about it.
 
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snoozer

Original poster
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May 15, 2017
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Still having trouble with the month old fan clutch. Seems like it stays engaged way to much. It has not thrown any codes. Sounds like a semi-truck revving up in lower gears.
Temp according to Torque Pro never goes higher than 206 today even when on the highway doing 65 mph the fan clutch felt an sounded like it was fully engaged, I could feel the power loss.
The shop who installed it keeps stalling around with doing something about it.
They said the pcm tells the fan clutch what to do blah, blah, blah
The PCM has the fan clutch update done to it, dealer did it before we bought it.
Is there anything else that could be causing this fan clutch to want to stay engaged more than not engaged. I mean it is not constantly engaged like the one I had replaced.
I think it is a defective fan clutch that they installed or just an inferior one.
This is our only vehicle & other than this fan clutch issue we like it.
If you have any suggestions for what might be causing the fan clutch to act this way, please let me know.
Thank you
Mark
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
What brand was it?
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
Never heard of them. Must be Cheap Chinese Crap.

One thing you can try is pull the fan relay and see if it quiets down. If it doesn't after driving a while, it's borked. Tell them you want a Hayden. They're the best price vs. quality. If they can't get it, you get it from Amazon or RA and get them to refund theirs.

Dorman is junk. ACDelco is too expensive
 

snoozer

Original poster
Member
May 15, 2017
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This morning other than roaring with first startup it quite down after a few minutes & I drove around for about 8 miles or so turn ac on & it did not get loud or pull the power down like yesterday. Will see what it does later when I head out again. The clutch that was on here when I bought it was never this loud or seemed to pull the power down until it stayed engaged permanently.
I will talk to the shop that put it on & insist they do something about it. Nothing like driving a little Trailblazer that sounds like a Mack truck. :wink:
Thank you for your replys
 

snoozer

Original poster
Member
May 15, 2017
45
Home
Never heard of them. Must be Cheap Chinese Crap.

One thing you can try is pull the fan relay and see if it quiets down. If it doesn't after driving a while, it's borked. Tell them you want a Hayden. They're the best price vs. quality. If they can't get it, you get it from Amazon or RA and get them to refund theirs.

Dorman is junk. ACDelco is too expensive

We just came back from trying to make a trip out of town & the fan clutch was a screaming & engine power was terrible & of course gas mileage sucked.
According to Torque Pro my temp never exceeded 206 when we were on the highway.
One thing I have noticed when sitting at idle I can not hear the clutch until driving it seems the higher rpms are the louder the noise is.
So after we got home I figured a would give your suggestion a try.
I removed the fan relay & drove around for awhile & I could not hear the fan clutch roaring & truck ran great.
Does this mean it is something else causing the fan clutch to keep being engaged fully when according the temps it shouldn't?

Thank you for taking the time to reply
Mark
 

Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
I think the clutch is functional but engaging too much for what the PCM is commanding or the relay is defective. Try swapping it with the headlamp relay and see what happens.
 

snoozer

Original poster
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May 15, 2017
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I think the clutch is functional but engaging too much for what the PCM is commanding or the relay is defective. Try swapping it with the headlamp relay and see what happens.
Tried it didn't make a difference. Talked to the shop who put the clutch in & he is having a Tech 2 look at it tomorrow at his expense to see if he can come up with what is going on.
I am not totally convinced it isn't a crappy or defective fan clutch. Wouldn't be the first time I have come across defective parts from O'Reilly's
My temps according to Torque Pro seem to hold pretty steady from 200 to 208 degrees of course with the fan clutch fully engaged run down the highway I am sure it is drawing in plenty of air to cool it down like that.
If I would have known then what I do now, I think I would have went with a 2008 fan clutch & had the fan codes removed.
Have you heard of any other issues by going with the 08 clutch & doing away with the electric clutch?
Once again thank you very much for your time. I really appreciate it.
 
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Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
I have the thermal clutch in my Saab and it's been trouble free. The only thing is the down time while you're PCM is out to be programmed, the truck is out of commission. At the same time, you can get some other mods done to the tune like shift firmness and better performance. Check with Jeremy at lime-swap.com (@limequat) for things to do. If you have the SAIS, get those codes deleted too.

If you would consider dropping a buck or two or becoming a member, it would be really appreciated to keep this site afloat. :smile:
 

snoozer

Original poster
Member
May 15, 2017
45
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I have the thermal clutch in my Saab and it's been trouble free. The only thing is the down time while you're PCM is out to be programmed, the truck is out of commission. At the same time, you can get some other mods done to the tune like shift firmness and better performance. Check with Jeremy at lime-swap.com (@limequat) for things to do. If you have the SAIS, get those codes deleted too.

If you would consider dropping a buck or two or becoming a member, it would be really appreciated to keep this site afloat. :smile:
What is SAIS?
Just made a donation
 
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HARDTRAILZ

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Nov 18, 2011
49,665
Secondary Air Injection System. It works for 30 seconds at startup for emissions and does nothing else. Typical fail item so just tune it out when you can and then when it dies....no worries.
 
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Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
Just checked and yours is an '03. I don't think you have one so no worries.
 

dna59

Member
Nov 20, 2015
327
Belize
When I replaced my fan clutch I initially had put in a Hayden which seemed to be highly recommended, but I had the same problems like you. It worked with no codes but was just too loud too often and I'm sure it robbed power from the engine. I ordered a Hella one and now the truck is only loud on startup and quickly quiets down.
 

snoozer

Original poster
Member
May 15, 2017
45
Home
When I replaced my fan clutch I initially had put in a Hayden which seemed to be highly recommended, but I had the same problems like you. It worked with no codes but was just too loud too often and I'm sure it robbed power from the engine. I ordered a Hella one and now the truck is only loud on startup and quickly quiets down.

Seems like the one the shop put on mine started out being very, very loud on cold start & warm start, but after a few blocks it would quite down, but as time has gone on it is getting where it is doing it more often.
I am beginning to think it is a crap shoot on whether you get a good one no matter what brand.
Quality of parts is not what it used to be that's for sure.
Thank you for letting me know there are bad Hayden's out there too.
BTW where did you order your Hella fan clutch from?
 
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shovenose

Member
Apr 24, 2016
318
SF Bay Area, CA
Why not have the shop warranty the O'Reilly one? Not going to cost you a penny. I will say I work there and haven't had many fan clutches come back, then again we don't sell very many.
 

Realism

Member
Nov 25, 2015
179
Idaho
I am going to say it is a Murray since this appears to be the only one that O'Reilly's carries & that is where the shop got it from.

Almost sounds like you have a Dorman installed. IIRC from previous threads the Dorman model requires the PCM to be flashed/updated to work with this brand so as to get the correct functionality from it.
 

snoozer

Original poster
Member
May 15, 2017
45
Home
Almost sounds like you have a Dorman installed. IIRC from previous threads the Dorman model requires the PCM to be flashed/updated to work with this brand so as to get the correct functionality from it.
Had it flashed with the update & it didn't help.
All is well now, put a 2008 Thermal Fan Clutch on it & having the fan codes removed by Lime-Swap with a PCM tune.
Just getting rid of that annoying electric fan clutch my truck has so much more power, of course running around with a fan clutch that thinks it should be fully engaged more often then not can really put a drag on the engine.
Thank you for your reply though.
 

David Mellado

Member
Jun 7, 2016
2
New York
I got this problem at first I just replaced the clutch but it did not fix it. The 10 amps fuse is ok, I switched the relay with the headlights relay and the headlights are just fine. I think its a wire issue between the fuse box and the connector. Because if I leave the clutch unplugged the car runs just fine, no excessive fan noise or overheating issues. That's why I think it's a wire issue. Does anyone have a diagram on how the wire goes feom the box to the connector? Or does anyone have another idea it would be very much appreciated.
 

mrrsm

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Oct 22, 2015
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Welcome to GMT Nation…

First… Visit this Link...and follow @Mooseman’s Instructions on How to Download a Digital GM OEM Service Manual Specific to your Year/Make/Model of Vehicle:

https://gmtnation.com/forums/threads/need-service-manuals-get-them-here.361/

Next … Search that Manual for the Chapters on Electrical Diagrams to find the one appropriate to the Electro-Viscous Fan Wiring and view the Wiring Schematic to trace down the EV Fan Circuit you seek.

Also… View this attached image of a weakness in the Wiring Harness Design of the EV Fan that shows how the Wire Bundle can wear through at the Fan Housing and Short Out…. Usually occurring on High Mileage Engines as such damage is vibration and friction related for the cause and origin of this issue:

SHORTEDEVFAN.jpg
 
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David Mellado

Member
Jun 7, 2016
2
New York
Thank you... 👍 your help is very much appreciated, I was able to download the information. I will work on it this weekend and will update later.
 

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