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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #1 · (Edited)
I appreciate all suggestions.

My 02 is now with 212k miles and I did swap the water pump about 2 months. Didn't think about the fan clutch but I am noticing when going up hill the temp hits 223f and sits for a bit. Just an hour ago it did the same thing after 2 hours of freeway driving and stopping for gas, another 223f, I got this number from a handheld scanner that I keep in the car with me.

I'm not used to these type of vehicles going past 215f but I'm worried due to age and mileage of my TB and don't want to be stranded.

Questions i have:
Anyone know how to tell if the fan clutch is going out?
Anyone use Dorman 622-001 clutch from amazon? There's a few with 4.5 stars rating and even under $100.
Amazon.com: Dorman 622-001 Engine Cooling Fan Clutch for Select Models : Automotive


2002 4.2 engine Trailblazer
Thanks.
 

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2002 chevy trailblazer_lt
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With a $13 ELM327 clone and an $8 app for an android phone you can monitor your actual fan speed and the desired fan speed. With this you can know if the fan clutch is doing what the PCM is asking it to do.

For about $50 you can get a WalMart branded version, the HT200 I think, of an Autel OBD scanner that reportedly can do the same without you having to do some setup. I haven't any first person experience with that one though.

57645
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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133 Posts
Discussion Starter · #3 ·
With a $13 ELM327 clone and an $8 app for an android phone you can monitor your actual fan speed and the desired fan speed. With this you can know if the fan clutch is doing what the PCM is asking it to do.

For about $50 you can get a WalMart branded version, the HT200 I think, of an Autel OBD scanner that reportedly can do the same without you having to do some setup. I haven't any first person experience with that one though.
Interesting, you think I can do this with my HPtuners? Already used a credit on the TB when I was going to tune it.
 

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2002 chevy trailblazer_lt
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I don't know HP Tuners but I would think it may be possible if they have the PID in there. I find it most convenient to grab this sort of data with a phone that I already have in the car!
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #5 ·
I don't know HP Tuners but I would think it may be possible if they have the PID in there. I find it most convenient to grab this sort of data with a phone that I already have in the car!
I will try tomorrow with HP tuners for the capability. I tried one of those ELM327 clones back in 2013 and didn't work at all but it was one of the early fake ones lol so that says it all.
 

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2002 chevy trailblazer_lt
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I will try tomorrow with HP tuners for the capability. I tried one of those ELM327 clones back in 2013 and didn't work at all but it was one of the early fake ones lol so that says it all.
The VeePeak mini bluetooth one I can vouch for. I have 2 of those and 3 earlier ones. The Veepeaks I have are reliable.
 

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2003 Chevrolet Trailblazer LT EXT
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If you "search" on here for fan clutch info you will find no lack of opinions about which fan clutch has worked well and which ones to stay away from
Basically, stay away from off brands and just stick with GM original fan clutches. They work the best and for the longest amount of time.
Kind of like spark plugs.....these trucks like the GM equipment the best
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #9 ·
If you "search" on here for fan clutch info you will find no lack of opinions about which fan clutch has worked well and which ones to stay away from
Basically, stay away from off brands and just stick with GM original fan clutches. They work the best and for the longest amount of time.
Kind of like spark plugs.....these trucks like the GM equipment the best
Man, I keep hearing that too. Stick with GM Original, Just these 2 clutches that have 4.5 star rating are on Amazon are tempting. 1 is dorman and the other is off brand but has twice the reviews at 500+ over dorman.
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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133 Posts
Discussion Starter · #10 ·
Man, I keep hearing that too. Stick with GM Original, Just these 2 clutches that have 4.5 star rating are on Amazon are tempting. 1 is dorman and the other is off brand but has twice the reviews at 500+ over dorman.
*EDIT ok I'm going to pull the trigger and buy from summit racing but with Rockauto price match @ $230.
 

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2002 chevy trailblazer_lt
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I have personally grabbed about 6 or 7 fan clutches from the Upull yard. Hayden, Behr, R&B industries (now named Dorman),, they all worked fairly well. Each cost me about $20 or so. I didn't pull them because I needed them, I wanted them for tests of how well they worked. A couple of them I opened up to have a look at the valve mechanisms. I shorted out two or three of the solenoid coils by trying out a suggestion of applying 12 volts directly to it. Don't do that. The coil windings are not designed for a continous voltage, they are designed for a pulsed power. They can't handle the wattage of a continous 12 volts.

For my use on a 2002 4.2 with the original factory PCM calibration any of them would be OK. The R&B industries (Dorman) gave me the lowest rpm when disengaged, sometimes too low and that results in it being too slow to engage when needed, in particular at idle with the A/C on. The Haydens seemed to run a little higher. I'm running a Behr right now and it runs about like the Haydens. Almost all my driving is highway where the fan isn't really all that needed. Generally at idle I see about the same as engine rpm, at highway 2000 rpm engine I see about 1100 fan speed. My PCM practically never applies the fan clutch unless I have come off the highway with the engine hot and I have the A/C on and get into slow traffic.

I have no idea what a new one would run like, never had one! Have never come across any AC Delco fan clutches at the Upull, maybe someday.
 

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2004 chevy trailblazer_lt
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Just my 2 cents worth, I would purchase on of the following: ACDelco, Hayden/4 Seasons (likely the same part, just different prices), or Behr/Mahle (the OEM supplier of this part). Yes, Dorman does have a lifetime guarantee, but in many cases Dorman parts have questionable quality and reliability.

When I replaced my fan clutch I purchased a NAPA TEMP fan clutch (manufactured by Hayden/4 Seasons) and it came with a lifetime warranty as well.

Good Luck!
 

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I just replaced mine but I went with the OEM GM thermal clutch from 08-09 (1540144), will trigger a SES code for ‘07 and older but that can be remedied with a tune and should be more reliable
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #14 ·
Had the hptuners plugged in today for another issue I had. I'm coming to conclusion that my fan is giving up.

1) upon cold start it no longer sounds like its running high speed. And I don't feel anything blowing at cold start.

2) its running a bit below 500 rpm when engine is @ 215f and thats at idle and driving

3) average rpm is 700 with 900 peak. For a second it will hit at 1100rpm

This point its worth swapping it out as the tb has 213k and I dont want to risk anything.
 

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I am not familiar with HP Tuners capabilities. Can you use HP Tuners to command the fan to engage?? If so you won't see much of a difference below 2000 rpm.

Alternatively, if you want to test your fan clutch and the solid state module that controls it use a length of light wire, 22 gauge or so. Most convenient to have it run into the cab. Wirewrap a stripped end to terminal #5 of the control module like so...

Circuit component Passive circuit component Electronic component Font Operational amplifier


Run the engine at about 1500 to 2000 rpm and ground the other end of that wire for 5 or ten seconds. A bolt in the door jamb is handy for the ground point. If the fan clutch and module are OK the fan will catch and roar. Remember that it takes 2 to 3 minutes at above 2000 rpm for the fan clutch to release after doing this.

Some have suggested to send 12 volts directly to the fan control valve solenoid to test a fan clutch. This will ruin the fan clutch as the solenoid windings are meant for pulse width modulated input only, not straight 12 volts DC.
 

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Just my 2 cents worth, I would purchase on of the following: ACDelco, Hayden/4 Seasons (likely the same part, just different prices), or Behr/Mahle (the OEM supplier of this part). Yes, Dorman does have a lifetime guarantee, but in many cases Dorman parts have questionable quality and reliability.

When I replaced my fan clutch I purchased a NAPA TEMP fan clutch (manufactured by Hayden/4 Seasons) and it came with a lifetime warranty as well.

Good Luck!
Alright, we will try AC Delco instead. Was about to order Dorman but it got mixed reviews. Still waiting for the truck to return from the installation of the new set of tires from 4Wheelonline before we can start the mod projects.
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #17 ·
Alright, we will try AC Delco instead. Was about to order Dorman but it got mixed reviews. Still waiting for the truck to return from the installation of the new set of tires from 4Wheelonline before we can start the mod projects.
where you buying the clutch?

I've been very busy dealing with an IRS audit and I'm getting money back!!! Therefore I still yet to change the clutch
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #18 ·
I am not familiar with HP Tuners capabilities. Can you use HP Tuners to command the fan to engage?? If so you won't see much of a difference below 2000 rpm.

Alternatively, if you want to test your fan clutch and the solid state module that controls it use a length of light wire, 22 gauge or so. Most convenient to have it run into the cab. Wirewrap a stripped end to terminal #5 of the control module like so...


Run the engine at about 1500 to 2000 rpm and ground the other end of that wire for 5 or ten seconds. A bolt in the door jamb is handy for the ground point. If the fan clutch and module are OK the fan will catch and roar. Remember that it takes 2 to 3 minutes at above 2000 rpm for the fan clutch to release after doing this.

Some have suggested to send 12 volts directly to the fan control valve solenoid to test a fan clutch. This will ruin the fan clutch as the solenoid windings are meant for pulse width modulated input only, not straight 12 volts DC.
Haven't been able to do any of the suggested testing as I been very busy. Also only been driving once a day 1 mile round trip for coffee.

I had data logged the fan speed with hptuners but deleted the log since I found out my microsoft account had been hacked into. I think i will just end up swapping the clutch. I know further testing is needed but really all this started after I swap the water pump which was very loose at the neck.

I forgotten the prices on the clutch but I might end up trying the doorman just to get by. Also I have forgotten to mention in the beginning the fan clutch Roars 1 out of 10 cold starts.

I might end up trying the testing as you suggested and have to clutch on hand.
 

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I'm in the steep learning curve on these fan clutches too - but I can say that I have never had a moment's trouble with mine and I know it's a Dorman.

It is stone silent in the AM startup, and until the temp registers 212°F on the gauge, I'll never hear it make any sound at all.

I like to cold start, let the engine idle for a few minutes - sometimes longer - and then drive the 3/4 mile down our frontage road art 25-35 MPH letting the tires get round (an old habit from the days of nylon cords) and the oils to get moving and doing their 'oil-things'.

After a couple of right-left-right turns, then I hit a 60 MPH zone for 3 miles until I get to the town outer limits.

All along that way there's never a roar at all and the gauge stays steady at 212°F all the time.

What I'm trying to say is that I believe I have a blessed relationship with my Dorman fan as it just plain-ol' works and never makes itself noticed. I know it has to be working else the gauge would climb to smoke-city - and that's never happened.

Maybe my gauge is broken and the default reading is 212°F all the time - I'm not too sure about that though..... like I said: A steep learning curve.
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Discussion Starter · #20 ·
I asked someone on Youtube about their replacement and they gave positive experience and gave me a link to the clutch they purchased


It's $72 and a $4 coupon bringing it to $73.99 after tax. Very tempting.

Anyone else use a non GM/Acdelco brand and have good luuck?
 
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