NEED HELP 2007 Trailblazer fan clutch questions

haymad

Member
Hey all,

So I just bought a 2007 trailblazer and overall it is in very good condition. Has 160k miles. Unfortunately, it didn't come with any previous service records. Anyways, when I got it I noticed that upon starting, the fan is engaged and runs extremely loud and louder when RPMs go up. This is with a cold engine. After getting up to speed on the hwy (70mph) for a bit and the engine warms up, this loud jet engine sound goes away and stays away even with low speed driving. During the whole process the temp gauge never goes over 210 but definitely gets up there pretty quick (maybe this is normal?). Ive been doing some research and see that these TBs have fan clutch and water pump problems. When I pull and swap relays 45 and 46 it has the same result (not sure if i'm checking the relays correctly). I am assuming that the fan clutch is failing in the engaged position. What do you think?

Also, I read that not dealing with this problem will put extra stress on the water pump causing it to fail soon after. I am going up into the mountains in a couple days and I don't want to have any problems as my wife and dogs will be with me and we have REALLY bad road conditions. Fortunately I can get all the OEM parts (new fan clutch, new water pump, might as well do new Tstat, and new Sbelt as well) before my trip up there but I just want to see if anyone has any insight on this before I replace anything for no reason. I want to get this thing running in top shape and I feel that it is not doing so right now.

Im going to take it up to Orielly right now to scan it and see if any codes pop up but I have personally seen NO check engine light. (If it aint broke dont fix it?)

Any insight or advice is very much appreciated. Im really happy to have this truck and I want to keep it in the best condition possible!
 

xavierny25

Well-Known Member

Mooseman

Moderator
How long does it take for the fan to disengage? It's normal for the fan to stay engaged for a few minutes while the silicone inside redistributes itself.
 

Redbeard

Well-Known Member
I have personally seen NO check engine light. (If it aint broke dont fix it?)

Thumbs up to the "If it ain't broke, don't fix it" My father tried to teach me that, but I was just too hard headed to believe it for 30 or 40 years. Good to hear your not just "throwing parts" at a problem.
 
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haymad

Member
How long does it take for the fan to disengage? It's normal for the fan to stay engaged for a few minutes while the silicone inside redistributes itself.
About 5-10 mins. The problem is that is stays in the engaged position sometimes from cold start all the way to 210 and after its been on 210 for awhile it stops. Then the very next time I start it cold it doesn't come on at all and then a little after the car has gotten to 210 it engages and wont disengage for the rest of the drive. It is acting erratically. There is no pattern to it. I cant figure it out...

Try that link for the fan issue.
Thanks brother. I apologize, I am new to using forums and didnt realize there was a "STICKY" about this or even know what a sticky was. That TECK LINK that was posted in the sticky is pretty informative if you read page 3, but Im still not sure why mine is acting the way it does.
 

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Mooseman

Moderator
It shouldn't take that long. I'd replace it. Hayden is our go-to for these. Dorman is junk.
 
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Mooseman

Moderator
ACDelco for these are overpriced. Hayden are good quality with a good price point. If you can find a Behr cheaper than ACDelco, they are the supplier to them.
 

speedbird52

Member
So, I have an 06 and this will be my third electronic fan clutch. Can I switch to a thermal clutch or is that a no-no? Tired of having issues with it.
 

Mike534x

Well-Known Member
So, I have an 06 and this will be my third electronic fan clutch. Can I switch to a thermal clutch or is that a no-no? Tired of having issues with it.
You can switch to the thermal one with no issues. Just keep in mind that you'll need a tune from @limequat or @Kelly@PCMofNC to tune out the check engine codes/program the PCM to handle the different style clutch. If you're going to go that route, ask about performance. You'll get your moneys worth going for either of them and a much more responsive truck as well. :yes:
 

Mooseman

Moderator
There's actually nothing extra for the PCM to handle. It's just to turn off the fan error codes. You can even put a thermal clutch in now and live with the CEL until you get it tuned.
 

coolasice

Well-Known Member
I believe the only difference is AC performance when not moving is diminished with the thermal clutch vs the electro one. At least that's what i have seen with my 2008, at a stop the ac begins to warm slightly as it can't pass enough air over the condenser. With the electro clutch the pcm could keep the fan fully engaged when the a/c was on and passed more air over the condenser.
 

speedbird52

Member
Okay, so here's a co-worker's theory on how the electro clutch is wired in. Help me make sense of this guy's "always has an answer to everything". He says (God, I hate saying that) that the fan electro clutch is somehow tied into the throttle body. AND, that if you have issues with one, you'll have issues with the other. Is there any validity to this or is he just as cracked as I think he is? (Honestly, I like the guy, but damn... he's got to be the smartest person in the room even if he's full of bullsh*t).

Cheers!
 

Mooseman

Moderator
It's controlled by the PCM. Uses different data like engine temp, A/C operation, possibly vehicle speed. This chart actually gives fan speed vs. temp and A/C pressures:



He is kinda right about the throttle and fan thing but only regarding issues with the 5v reference line as they share it. It has happened where the fan was shorted out and prevented the throttle from working.
 

Mike534x

Well-Known Member
There's actually nothing extra for the PCM to handle. It's just to turn off the fan error codes. You can even put a thermal clutch in now and live with the CEL until you get it tuned.
Really? That's even better. Wasn't sure if swapping the two required anything besides turning off the fan codes.
 

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