Monday, August 22, 2011

Noise comes from rear rear right inside the trunk on chevy trailblazer ?

There are many others facing this noise problem on Trailblazer :---

READ this conversation :---

EXPERT:---
Is it a ticking sound? Sounds like it might be the actuator that is back there for the rear air controls. But they tick when they start to go bad. They don't knock unless it is stripped and it is trying to move the door and it is the door that is knocking. I have never heard of that happening but anything is possible.

CUSTOMER:--- THIS IS MY PROBLEM :---
My 06 TB is making a loud clacking sound from behind the plastic panel on the passenger side of the rear cargo area. It happens even with the key just turned to accessory, without the engine running. Seems to do it for a minute or so then stop. Any ideas? Maybe something with the rear a/c? PLEASE HELP.
Thanks!

CUSTOMER GIVES MORE DETAIL ON SAME PROBLEM :----
What I did notice was that if I put the rear a/c control to rear, I can make the noise stop by adjusting which vents are being used in the back. While it is changing, it stops clicking.


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THIS IS EXPERTS REPLY TO CUSTOMER:----
Nah, normal TBs doesn't have the air suspension, only the SS.

Does the noise change speed/sound if you change the rear fan from lo to hi? - I'm thinking its the rear fan motor for the hvac system. Maybe somebody dropped or pushed something into a vent, or the motor stator has oxidated. (A few minutes on hi should temporarily eliminate the problem if its an oxidated motor).

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THIS IS ONE MORE REPLY FROM EXPERT TO CUSTOMER :--
There are two servos that operate the rear air, one of them is most likely bad and needs replacement.

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REPLY FROM CUSTOMER:---
THANKS,My problem SOLVED.-------
"There are two servos that operate the rear air, one of them is most likely bad and needs replacement."

There is what appears to be a servo with a 4 wire (I think) connector going to it. It's mounted sort of diagonally If I recall...anyway, I pulled the connector off and the noise has stopped. The fan is still blowing back there....does that servo just direct the air to selected vents? If so, it's blowing out of the ceiliing vents now, and that's where we always use it. Would it hurt to leave it for a while?

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REPLY FROM EXPERT:---
It would probably be fine, when mine went out it would only blow cold air out of the rear. When you do decide to replace it the part # is 88892975 and I paid $58.16 for mine.
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YES very correct expert, this is reply from customer:---

This is what i did :---
It is in the rear right cargo area. I had to take all of my right side panels off to get to the rear air setup. What goes out is the rear A/C Vacuum Actuator. There are 2 in there. My lower one went out. What this little gear driven box does is that it switches the rear air from upper vents to the lower feet vents. The gears inside go bad and it clicks. I changed mine and all is well now.

There are TWO actuators in the rear - a mode and a temp actuator. Any of the one can go faulty, damaged and cause this thumping noise.-----