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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
My clutch fan does not engage at all....which wire ont the harness to the fan sends the voltage to turn it on....or is there a temp sensor that might be bad?
AC works fine when moving but the fan will not come on. Thinking of going electric.
 

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2004 gmc
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All five wires in the harness are essential. Power, ground, and three wires for the RPM sensor. Power comes from a fuse by way of a relay in the front fuse block. But the most common failure is the fan clutch itself, not the power feed to it. Especially in pre-2005 vehicles like yours, when GM redesigned the fan clutch for improved performance and reliability.

Lots of discussions you can find in a search for "fan clutch". Especially interesting to learn about its theory of operation is one with the title "Fan Clutch 101"

"Efans" is also another fruitful search term. ;)
 

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Recently changed water pump in my 2005 trailblazer, and in the process the fan clutch actuator got a couple of small bumps, along with having to piece my fan shroud back together it was very brittle and broke in half. Would the fan be getting stopped by the shroud by chance or the actuator not functioning and telling the fan clutch to lock and spin with the motor?
 

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2003 chevy trailblazer_ltz
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Would the fan be getting stopped by the shroud by chance
Spin the fan, see for yourself. No way for us to know how you put the fan shroud back together.

or the actuator not functioning and telling the fan clutch to lock and spin with the motor?
Sure, you could have a defective fan clutch. What engine is this? If it's the electronic clutch, you could also have a popped fuse, or poor electrical connection in the harness somewhere.
 

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2004 chevy trailblazer_lt
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Everyone agrees to the following: Genuine GM/ACDelco and Behr/Mahle; some have had good luck with Dorman electronic fan clutches, and some others have had luck with the Four Seasons/Hayden/NAPA Temp.

Good Luck!
 

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'05 Chevy TB EXT
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Everyone agrees to the following: Genuine GM/ACDelco and Behr/Mahle; some have had good luck with Dorman electronic fan clutches, and some others have had luck with the Four Seasons/Hayden/NAPA Temp.

Good Luck!
I did a fan clutch in a Dodge 5.9 TDX and used the Dorman brand --- so far, so good.

It seems to me that Dorman is stepping back up to the plate after all these years of hit-or-miss parts quality. Let's hope so anyway!
 

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2004 chevy trailblazer_lt
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I'll keep my fingers crossed that not only Dorman, but all the other auto parts manufacturers/name brand parts vendors also improve their overall quality and not solely rely on statistical quality assurance/control for parts to last for X number of years.
 

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'05 Chevy TB EXT
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"Batch sampling " has always been a crapshoot ... with liabilities and lawsuits.

The next denominator is "Lowest bidder" from an outside producer.

Imagine sitting on top of a huge explosive device in a NASA space capsule, KNOWING that everything was built by "the lowest bidders"!
 

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2004 chevy trailblazer_lt
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Yup. Your last line reminds me of a line that Steve Buscemi had in the movie "Armageddon" - said essentially the same thing!
 

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2004 chevy trailblazer_lt
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What do you need help with?
 

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trailblazer ñtz 2003 4.2
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Omg thank u for answering. Ok i got the entire wiring harness to the fan clutch but now rewiring is the issue. I don't know exactly what wires from my truck/computer are the ones i need... I know there 5. How can I find out which is which
 

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2004 chevy trailblazer_lt
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Hold on while I get a wiring diagram. Be back shortly.
 
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OK. Attached is a pdf file with 2 schematics for the fan clutch. The first one is for an automatic HVAC system and the second is for a manual HVAC system. There is likely minimal difference between the two for the fan clutch.

The fan clutch is found on the far right hand side in each page and is near the middle.

Hope this helps you out.

Good Luck!
 

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