clicking sound near fan clutch

[gkrenzer]

I am glad I found you guys. It has been several months since I used the other site and was kinda out of the loop. Didn't know you moved

Sorry but I have a "fan clutch" ?? for you.
I had a clicking sound on my 03 trailblazer (100K miles) that disappeared when I disconnected the link to the fan clutch.
Then I started getting SES messages. It was the engine coolant temperature warning that indicates bad therm or coolant sensor. I replaced them both and then I replaced the fan clutch and serpentine belt. Took me all day but I got it done.
Now:
No more SES warnings and temperature is rock solid at 210 degrees but it still clicks (2 per second) The clicking sound only occurs when vehicle is up to temperature (about 210). I unplugged the fan clutch while it was clicking and it stopped

Also... the fan is always spinning. I thought the clutch caused it to spin only when needed. If I am wrong about that, somebody tell me

Any thoughts on what is going on?

 

[MMIN]

I'm on my 5th fan clutch now and I got the clicking sound I think on number 4.. It should only do it at idle/low rpms. There is an update for the PCM that should take care of it for you. It is very picky at what RPMS it clicks at I think the update may just slightly change where the truck idles but that's a complete guess to be honest. I don't believe it hurts anything it's more just annoying.

 

[The_Roadie]

No more SES warnings and temperature is rock solid at 210 degrees but it still clicks (2 per second) The clicking sound only occurs when vehicle is up to temperature (about 210). I unplugged the fan clutch while it was clicking and it stopped

You need to pay a dealer for the 2005+ PCM update to help the noise, and also obtain the benefit of more cabin cooling on hot days right after start-up.

Also... the fan is always spinning. I thought the clutch caused it to spin only when needed.

The clutch adds friction between the fan blades and the pulley that spins it. If it's fully engaged, with maximum friction, the RPM of the fan will be very close to or the same as the RPM of the pulley. If the engine doesn't need so much cooling, the commanded friction will be lower, so there's slippage. But there's nothing that stops the fan from spinning - you can spin it by hand when the engine is off. So RESIDUAL friction will always keep the fan blades spinning, slowed down only by air friction. It's a wimpy spin when not commanded to be powerful.

If I am wrong about that, somebody tell me

That sad duty seems to fall on me too often.

 

[gkrenzer]

Thanks for the input guys. I am glad to hear that my work (and scraped knuckles) may not have been in vane after all. I will look into getting the PCM update.

By the way, what exactly does PCM stand for? Is it the software update I read about in posts on the old site? Any idea how much it will cost?

 

[MMIN]

By the way, what exactly does PCM stand for? Is it the software update I read about in posts on the old site? Any idea how much it will cost?

Powertrain Control Module.. We usually charge a $45 diagnostic fee but I have no idea what a dealer would charge maybe someone else will chime in.

 

[The_Roadie]

Yes, call your local dealers. Some charge an hour minimum for a ten minute job.

 

[gkrenzer]

thanks for the assist. Got the computer update. No more clicking and the engine is noticably quieter. THANKS

 

[n0kfb]

thanks for the assist. Got the computer update. No more clicking and the engine is noticably quieter. THANKS

What did you pay for the work?

-- Dan Meyer