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2004 chevy trailblazer_ls
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Discussion Starter · #1 · (Edited)
As the title says, 2004 trailblazer.

I replaced the fan clutch from one from Rockauto. There was a Behr unit in there, not sure if thats factory or it had been done once before already. 77K miles.

After replacing the fan clutch, I heard the fan start in the vehicle when i hadn't heard it in a long time. Now I haven't heard the fan again since being replaced. Temp is steady at 210, always has been. Never had an overheating problem. I'm thinking there is another problem, but don't know where to start. Temp never went over 210 with the fan clutch that was in there before, so I suspect that the part was/is fine.

I would give 2 ****s less about the check engine light, but I can't get this thing to pass emissions here in GA if there are ANY codes present.

Truck is driving me crazy, any suggestions?
 

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Hi,
Do you hear the fan starting at high speed when you start the engine cold?
It should do that for a round 30 seconds then goes down to whispering.
If not, The Tenp sensor is faulty.
 

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Discussion Starter · #3 ·
which temp sensor, the one in the fan clutch itself?

The fan did this the first time I started the truck after installing it, but never after.


Bad dorman fan clutch out of the box then?
 

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The fan clutch has no TEMP sensor built in, but it DOES have a speed sensor, to make sure the actual fan RPM agrees with the commanded fan RPM. The fan might spin as commanded and cool properly, but with a bad feedback sensor, the code will continue to show up.

Was your replacement from Rockauto a Dorman? LOTS of bad reports about their reliability out of the box in the last few months. I think it's time for somebody to give them a call.
 

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Discussion Starter · #5 ·
Yes, fan was ordered from rockauto, it's a dorman brand I believe (140 or something shipper). I'll call the dealer as well and see what a fan will cost from then in the hopefully unlikely event the second fan rockauto sent me is bad as well.

Good thing I figured out how to change them out in about 20 mins tops :D
 

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which temp sensor, the one in the fan clutch itself?

The fan did this the first time I started the truck after installing it, but never after.


Bad dorman fan clutch out of the box then?
The Temp sensor is located on the cylender block behind the alternator. It's your problem if the engine overheats in city driving (low speed and heavy traffic).
 

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The Temp sensor is located on the cylender block behind the alternator. It's your problem if the engine overheats in city driving (low speed and heavy traffic).
It's a possible cause of overheating, but it would be obvious that the gauge would be reading low. The original poster said his gauge was always solid at 210.

A low temp sensor reading COULD cause low fan speed to be commanded, but I don't know any other way it could interact. And a bad temp sensor would not cause a fan clutch code to be displayed.

The THERMOSTAT behind the alternator is a more likely suspect for overheating.

Again, to be perfectly clear - there is no temp sensor in the fan clutch - only an RPM sensor.

If it isn't a bad fan clutch, then it's chafed wires in the harness going to the clutch. The TSB is attached.
 

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Discussion Starter · #8 ·
The brand new fan clutch had no chaffing problems (obviously), the one I replaced had evidence of chaffing but no exposed wiring.

Temp gauge is rock solid at 210. I mean, occasionally it will move a hair over to the right, or dip a hair to the left....but the needle is always on the line indicating 210.

I guess I got a bad unit out of the box ?
 

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I just put a Dorman (Behr) fan clutch on my TB. Got it at O'reilly's. My temp. gauge used to get as high as mid-way between 210 & 260. Since the replacement, it's only gotten as high as the first mark past 210. Would you call this normal? (Of course it hasn't been over 100 degrees lately in Texas so it hasn't gotten the true test yet.)

I do get the high speed fan noise at cold start-up for about 30 seconds so I assume my FC is operating normal? (Replaced FC, water pump, hoses, thermostat, and 50/50 Dexcool.) I've never received a code. (I can start a new thread if need be as I don't want to high jack this thread.)
 

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Your report is OK here. Good to know your temp came down. The 30 second noise is normal. You may benefit from a dealer PCM update since you're from before 2005, which should improve initial cooling when you need a lot of AC capacity for the cabin cool-down but the radiator isn't hot enough to command lots of fan RPM on its own.

What do you mean (Behr) in parentheses after Dorman? I thought the Dormans were their own aftermarket brand and Behr was the OEM contractor. Do you see Behr on the packaging or the unit?
 

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Discussion Starter · #15 ·
Took me about 20 mins to swap in the new dorman replacement that arrived today.

Did the same thing the last one did, fan ran for about 30 seconds on high the first time I started it. I didn't clear the code as I have no scanner. Hoping a few short drives tonight will do it. If not tomorrow morning I'll get it cleared and cross my fingers. Dunno what else to do if this doesn't work.
 

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I sent an email to RockAuto asking for a response to the Dorman replacement issues cited in this thread. I just received a replacement and am reluctant to install it based on the comments in this thread. Let's see what the response is.

My error code was the RPM command vs. feedback error - no temperature issues.
 

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.....Good thing I figured out how to change them out in about 20 mins tops :D
I will be ripping this off for an efan replacement and am wondering what you figured out so I can tackle this much faster!
I been eye balling what I need to do and thinking out an attack plan!
That sure is a large bolt to grab!

thanks. hope your is still working today ;)
 

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Discussion Starter · #18 ·
Made a tool out of a piece of steel, about 30" long with a hole drilled in the end.
It only bolts to the water pump with one bolt.

My install:

Remove one bolt from the water pump, install tool
use a large cresent wrench on the big nut, with a cheater bar on it (pipe). Break the large nut free. You are now 50% there.

Back off the large nut almost all the way. Now unbolt the fan from the fan clutch. Remove the fan clutch plug, and remove the fan clutch from the water pump. Helps to have small hands (I don't) or to no care if your hands get hurt a bit (I don't). Lower the fan clutch inside the fan shroud while pulling out the fan itself. Once the fan is out, reach down and grab the fan clutch.

Install is the reverse, but beware that it's harder to get the fan back in there while trying to hold the fan clutch up. It'll work just fine, just takes some ****ing around with. Sure beats removing the upper hose, getting coolant everywhere, pulling the shroud, blah blah.
 

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Took me about 20 mins to swap in the new dorman replacement that arrived today.

Did the same thing the last one did, fan ran for about 30 seconds on high the first time I started it. I didn't clear the code as I have no scanner. Hoping a few short drives tonight will do it. If not tomorrow morning I'll get it cleared and cross my fingers. Dunno what else to do if this doesn't work.
Hey I had this problem, but if you get the code and then fix it, you MUST clear the code first to get everything to work right, because i did it on my scan gauge while it was running and it was an instant difference...hope that helps, but sometimes it should go out on its own though
 

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I sent an email to RockAuto asking for a response to the Dorman replacement issues cited in this thread.
Dorman has been unresponsive to my message. Time to hit them up again. Or else they go into the "do not recommend this vendor" list.
Hey I had this problem, but if you get the code and then fix it, you MUST clear the code first to get everything to work right,
What specifically changed when you cleared the code? The fan sped up or slowed down? I would have guessed that the fan was operating at the right speed, and only the RPM feedback sensor was goofed.
...because i did it on my scan gauge while it was running and it was an instant difference...hope that helps, but sometimes it should go out on its own though
The shop manual has the exact conditions listed for auto-resetting error codes, and IIRC without looking it up, this is one of the 3-drive-cycle ones. If you fix the problem, the SES light will go out after three cycles of starting the vehicle cold, driving around for some minimum length of time, then turning it off until it gets cold again. The code then goes into a history section so a scan tool can see what had been going on even if it was intermittent.
 
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