Junk fan clutch replacement or something else?

Hi everyone, long time lurker first time posting. I have a 04 trailblazer ext with 4.2 that was given to us just over 2 years ago so unfortunately I dont know much of the history. The problem is its running hot (230 degrees if I let it) and I think I've got it narrowed down to the EV fan clutch. I've replaced the water pump and thermostat with acdelco, new coolant sensor, flushed radiator, and finally new clutch. The fan clutch was a no name brand which I realize now is not recomended. I believe its working but only for the first 15 minutes of driving. I've done the grab the fan and stop it, checking for a pulse(it does) I can jump the white wire with 12 volts and it engages hard, same with jumping the relay from the 5 to 6 pin I believe. when it starts climbing up in temp it doesnt seem like the clutch is engaged hardly if at all? When I shut the engine off I'll watch the blades and it appears to spin 2 full revolutions, I'll check the blades in 5 mins by spinning by hand and I'll get 1 revolution. If i wait an hour half a revolution as if the cooler it gets the more engaged it becomes. Sooooooo all that explaining to ask is this just a junk fan clutch or do I have a problem with a relay? (swapped 45 and 46 too) Problem with PCM? what other "checks can I do" TIA
 

Mooseman

Moderator
Hi and welcome.

You've done all the right things up to this point. How are you getting this temperature reading? With a scanner or other method of getting live data? If using an ELM327 adapter and Torque, there are custom PIDs you can use to see the commanded and actual fan RPM. I've asked @TJBaker57 for specifics on the custom PIDs to do this.

230 isn't terrible, especially if it's really hot out and running the A/C but according to this chart, the fan should be commanded between 39-56%, which would be fairly noticeable in air movement. Maybe the cheap clutch has a hard time with partial speed commands or fails once it gets hot. The fan running for the first 15 minutes may just be part of the warmup that happens until the silicone gets redistributed in the clutch.

I'd ditch the cheap clutch and go for either a Hayden (our usual go-to) or an ACDelco (pricey). Another option would be to get the much more reliable thermal fan clutch for a 2009 TB and have the codes for the EV clutch tuned out.
 

Blckshdw

Moderator
My question would be, once you notice the temps get uncomfortably high, if you jumper the clutch so it comes on full power, do your temps start to come back down? Do they hold steady, or worse keep climbing.
 
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PlumberKev

Member
Thanks for the replies so far. I have a scan tool that allows me to see the coolant temperature but not much more then that. I'll drive it around and watch the temperature and it's within a couple degrees of what the gauge is saying. I don't know about the special adapter but it sounds like it will do more than my scan tool so I'll have to look into that and maybe the thermal clutch is the answer. Yes when I've jumped the clutch after arriving home with high temps, the fully engaged fan cools it back down at a decent pace, I haven't tried it with jumping the relay but I'm assuming it will have the same result.
 
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PlumberKev

Member
I guess I should mention that yes it's hot out, daytime temps are nearing 110. All this is being done with the ac running.
 

Blckshdw

Moderator
The ELM adapters can be found for pretty cheap, the ones I've bought for myself, as well as friends/family were never more than $10. The app is designed well and can read a LOT of data. Just have to take the time to setup your displays to show you what you want/need.
 

TJBaker57

Well-Known Member
I'll try to be brief as my cable internet is down and in this remote area that means everyone is on cell service now so that is spotty at best!

If you're a techy sort you can go far with these little Bluetooth elm327 clones. Some will say they don't do much but that is a limit on the users part and/or the software they choose, not the device. I even recently discovered how to command my fan speed to 100% for a short time using just the elm327 and my phone!

I can confirm this current offering works well. Many of these Chinese clones are known to be flaky and all the talk of 'new version' is just BS.





In your current situation a good thing to know would be Commanded Fan Speed vs Actual Fan Speed. The ELM327 adapter can get these with the Torque Pro smartphone app as well as other apps that allow user entered PIDs.

A question: how well is your AC working in that 110 degrees you speak of? In particular how well does it seem to work in traffic, low speed, or stopped in traffic? Have you done or had done any AC service work? Reason I ask is I believe the Fan Speed is supposed to be Commanded higher in response to AC high pressures.
 

MRRSM

Lifetime VIP Supporter
Some additional potentials for causing "Thermal Over-Soaking" issues to investigate as any of these, all and singly, can overwhelm even a well functioning Electro-Viscous Fan:

(1) Long overdue for a Dexcool Coolant Change AND Radiator Flush.
(2) Clogged Cabin Heater Core.
(3) Clogged, Externally Dirty or Blocked Radiator (Stuck Large Leaves or Plastic-Paper ).
(4) Clogged Transmission Cooler Lines.
(5) Thermostat.
 
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PlumberKev

Member
The ac seems to be working ok, not as good as my other vehicle(05yukon) but ok. It's a little hard to judge because before the original clutch was changed the air was not good at all. Turns out on the old one that the fan itself somehow cut a groove into the wiring. So I guess in short sometimes the ac is decent and others not so much. The ac is what got me looking at the fan clutch in the first place, never would have guessed that if it want for finding this site.

The radiator was flushed last week along with a new thermostat and coolant temperature sensor last week but I'll check the other items soon.
 

TJBaker57

Well-Known Member
Well now there's a coincidence, I also have on 05 Yukon. And the Bluetooth elm327 clones will work there also.

You stated the system cooled at a decent pace when the fan clutch was jumped. 'Jumped' would be 100% duty cycle, seldom seen under normal operating conditions. An ugly possibility might be that the fan is operating as designed but the engine is developing more heat than it would under normal conditions. You have already addressed the water pump and thermostat as well as radiator flush and refresh. Are you experiencing any loss of coolant that cannot be seen leaking anywhere?
 
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PlumberKev

Member
I don't believe I'm having any coolant loss, at least I haven't seen any obvious signs. I'll give it a good look over when I get home. Sounds like the ELM327 is a great late father's day present.:celebrate:
 

Mooseman

Moderator
Apart from high outdoor temps, on thing that does cause some higher than normal coolant temps, all else being equal, is a clogged cat. The tranny could also be throwing extra heat into the radiator. Does it have an aux cooler by any chance? That could also help with temps and also tranny longevity.

Maybe give the radiator and condenser a good flush with a hose. Some have had a bunch of dirt and sand preventing good air flow.
 
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PlumberKev

Member
So I ended up checking for coolant leaks and didn't see anything. I took off the radiator cap and noticed white flakes floating. I'll see if I can figure out how to attach a picture. I'm reading it could be from tap water from previous, clear to head gasket problems. Since the TB takes a while to heat up and I can get it to cool back down I'm thinking no on a head gasket problem. To answer other questions, over the weekend I took off the front plastic to expose the radiator, checked for airflow blocks and then used a ac coil cleaner to try and clear any unseen grime.
 

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PlumberKev

Member
So I realize this is a long shot, but is there any way to test the wires and harness that connect to the fan clutch; as in the connection at the fan shroud? I'm wondering if maybe I have a broken wire. I messed around with trying to get voltage readings and continuity but I openly admit I have no clue, even with a wiring chart. Just wanted to try something like that before throwing another clutch at it.
 

MRRSM

Lifetime VIP Supporter
ScannerDanner does an excellent job in this Video of showing How to Investigate the EV Fan Cooling Circuit and functionality test using a High End Scanner Diagnostics, some Back Probing of the Harness per your concerns and provides the EVFC Circuit Wiring Diagram, too:

 

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