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Hi!

So day 2 with the new Nox and I've detected a curious problem. Hwy speeds with recirculate on I am getting a thumping noise from the rear. When the recirculate is turned off to get fresh air, the thumping goes away. I've narrowed it down to the rear cabin vents they install in cars to relieve pressure inside the cabin. From what I understand though - it shouldn't be trying to 'vent' if recirculate is active as it's pulling in it's own cabin air into the HVAC system.

So before I go to the dealer I've been looking around and decided to check the mode door for inside/outside air. What's interesting is sitting idle and choosing between recirculate on/off - the mode door doesn't move... It did after awhile of poking around in there to see if it was stuck... So turned off the car, waited and started it again. The mode door started acting funky again. The only way I can reliable change the function is if I turn off the HVAC completely, select the mode back and forth and then the door moves.

I did check to make sure I turned off all "auto" functions I could see on the system.

And really I don't know if the two things are even related? I know the vents start venting if outside air is selected and the air needs to escape so the pressure doesn't build up.

Soooo I'll keep this post updated - I will have to call my dealer service contact in the morning to see if there is even a fix for this yet.

T
 

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Thumbing noise in rear end

I too am getting a thumping noise in the rear end of my equinox. I've had the 2018 premier edition for two months now. At speeds over 45 miles an hour I get this thumping sound that it sounds like it's coming from the rear end and I am not sure what it is. I thought it was the gas banging around because it does it from when I have 3/4 of a tank of gas or less. Never thought it was part of the AC unit, I run it on fresh air no recirculation and it makes this sound. Not sure what it is but I guess I need to bring it to the dealer to find out why.
 

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Service Information




Document ID: 4849237
#17-NA-265: Flutter or Boom Noise from Rear of Vehicle - (Aug 21, 2017)
Subject: Flutter or Boom Noise from Rear of Vehicle
Brand:
Model:
Model Year:
Date Breakpoints:
Engine:
Transmission:
from
to
from
to
Chevrolet
Equinox (VIN X)
2018
2018
SOP
Ingersoll Assembly built prior to June 1, 2017
Ramos Assembly built prior to June 23, 2017
San Luis Potosi Assembly built prior to June 26, 2017
All
All
GMC
Terrain
2018
2018

Involved Region or Country
North America, N.A. Export Markets
Additional Options (RPOs)
Condition
Customer may comment on hearing a flutter or boom noise from the rear of the vehicle. The noise is most noticeable while driving above 25 mph, with the HVAC off, or in recirculation mode.
Cause
The cause of the condition may be the rear pressure relief valves (PRVs) opening and closing.
Correction

[/URL]
Note: The installation of an acoustic insulator panel (1) and block (2) will help to dampen the noise.

Verify the condition and install a rear acoustic insulator panel and block, following the repair steps in the Service Procedure below.
<a id="d1852e212">Service Procedure

  1. [/URL]
  2. Remove the rear fascia and both rear pressure relief valves (PRVs). Refer to the appropriate Body Pressure Relief Valve Replacement procedure in SI.
  3. Install the acoustic insulator panel along the backside of the chamber between the rear body panel and the inner rear panel, following these steps:
    1. [/URL]
    2. Slide the insulator panel (1) into one of the PRV openings.
      [/URL]
      Important: Ensure that the insulator panel is centered and DOES NOT BLOCK any of the holes in the body.
    3. Center the insulator along the back side of the chamber.
    4. Tuck the outside edges of the panel into the corners.
    [/URL]
  4. Install the acoustic insulator block (1) in the middle of the chamber, between both PRVs.
    [/URL]
  5. Reinstall both PRVs and the rear fascia. Refer to the appropriate Body Pressure Relief Valve Replacement procedure in SI.
<a id="d1852e275">Parts InformationCausal Part
Description
Part Number
Qty
N/A *
INSULATOR ASM-BODY RR PNL
84313892
1
N/A *
INSULATOR-R/END LWR PNL REINF
84313893
1
* For warranty transactions, DO NOT mark this/these parts as the Causal Part. Enter the word “Bulletin” in the Causal Part Description free-flow text field.
<a id="d1852e359">Warranty InformationFor vehicles repaired under the Bumper-to-Bumper coverage, use the following labor operation. Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information.
Labor Operation
Description
Labor Time
1480868*
Rear Acoustic Insulator Panel and Block Installation
1.6 hrs
*This is a unique Labor Operation for Bulletin use only.
Version
1
Modified



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Wow - I can't believe GM's testing of the new vehicles did not reveal this problem before production. I wonder how many people will put up with the noise or their dealer will tell them that the noise is normal? Sounds like the vehicle was rushed into production and there many be other design flaws and defects.
 

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any body had the repair done and did that stop the noise, I am getting the same issue on mine

It's under warranty, it's free. . . . get it done. .. :smile:
 
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I have had my 2018 Nox back twice for this noise and they claim they can't hear it all the time. When I brought it the second time I had everything out of the back including the spare tire. I had the assistant service manager sit all the way in the back in the spare tire well and he said he could hear it when I was doing about 30 mph and it got louder the faster I went. He called me after and said they couldn't fix it because the noise went away. I was really pissed because anybody who sat in the back was saying the noise was always there. After I brought it home me and my son started driving around trying to find the noise. Found out the HVAC has to in recirc mode to make the noise. Found the noise in the rear vent flapping open and closed or as GM calls them pressure relief valves. Found this bulletin in this thread and I called them and made another appointment and referred to this document number. They are saying they can't find the document. I emailed them a copy and they wanted to know where I got it. I am bringing the Nox in Tuesday and a copy of this document and I am going to stand there and make them do this. Wish me luck! I will let you know how it turns out.
 

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So what does it actually sound like. Is it a thumping? Its not really loud but loud enough to hear right?


I haven't had this problem myself but curious to see what I should listen for.
 

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Discussion Starter #11
Sorry everyone for not posting more recently! End of summer fun I guess heh.

Anyways, I've had a piece of paper from the dealer in my glovebox that has the doc ID 4837929. This was found when the service guy looked up my vehicle by vin - but the issue is as described on what BigB posted. "Interior Boom Noise While Driving Above 25 MPH" and "At cruising speeds with the HVAC system off or in recirculation mode a boom noise will eminate from the rear of the vehicle." Direct quote - interesting to see "eminate" spelled wrong lol.

As far as the other issue of not always going into recirc - I've chalked this off as it's part of the system being set on auto because it does eventually switch properly after driving a few miles and the cabin cools down.

T
 

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Discussion Starter #12
So what does it actually sound like. Is it a thumping? Its not really loud but loud enough to hear right?


I haven't had this problem myself but curious to see what I should listen for.
The first thing that comes to mind is it's like someone is clapping their hands over your ears (but more distant and not as painful). What got me was the pressure changes that came with that - it makes my ears constantly pop. It is kinda loud too really.

The ONLY way I found it was to have someone else drive while I pulled up the cargo cover (LOVE this feature btw) and poke around back there until I found those vent holes and I was actually able to watch them slap open and closed.

I've seen a few complaints of this on Chevy's Equinox Sponsored FB posts.

My service guy said to check on it again when I get to my next oil change - there's just one problem.... I bought the **** car at the end of June and I don't think I've even hit 1200 miles yet! I have a take home squad car so that's where the miles go. I think I'l try and call my service guy and see if he can find the fix and if I can get it scheduled.

If I think about it, I'll attempt to get a sound clip with my phone back there while I drive. No laughing but I spent probably a good 45 minutes one night when I first found this driving a mile, messing with the liftgate bumpers and on and on. I gave up until I found what was actually doing it.

Updates to come!

T
 
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I have had my 2018 Nox back twice for this noise and they claim they can't hear it all the time. When I brought it the second time I had everything out of the back including the spare tire. I had the assistant service manager sit all the way in the back in the spare tire well and he said he could hear it when I was doing about 30 mph and it got louder the faster I went. He called me after and said they couldn't fix it because the noise went away. I was really pissed because anybody who sat in the back was saying the noise was always there. After I brought it home me and my son started driving around trying to find the noise. Found out the HVAC has to in recirc mode to make the noise. Found the noise in the rear vent flapping open and closed or as GM calls them pressure relief valves. Found this bulletin in this thread and I called them and made another appointment and referred to this document number. They are saying they can't find the document. I emailed them a copy and they wanted to know where I got it. I am bringing the Nox in Tuesday and a copy of this document and I am going to stand there and make them do this. Wish me luck! I will let you know how it turns out.


How did it turn out?
 

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Discussion Starter #14
I have had my 2018 Nox back twice for this noise and they claim they can't hear it all the time. When I brought it the second time I had everything out of the back including the spare tire. I had the assistant service manager sit all the way in the back in the spare tire well and he said he could hear it when I was doing about 30 mph and it got louder the faster I went. He called me after and said they couldn't fix it because the noise went away. I was really pissed because anybody who sat in the back was saying the noise was always there. After I brought it home me and my son started driving around trying to find the noise. Found out the HVAC has to in recirc mode to make the noise. Found the noise in the rear vent flapping open and closed or as GM calls them pressure relief valves. Found this bulletin in this thread and I called them and made another appointment and referred to this document number. They are saying they can't find the document. I emailed them a copy and they wanted to know where I got it. I am bringing the Nox in Tuesday and a copy of this document and I am going to stand there and make them do this. Wish me luck! I will let you know how it turns out.
Try having your dealer look up the document by your VIN number - that's how my dealer found it.

Off topic - how does one edit a post? I can't figure it out heh. I don't know what I said in my above post but it bleeped out whatever it was! *Disregard - they must have a time setting on this because right after I posted this I saw an edit button.

T
 

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i had this modification done and it still does it---what has anyone done now ? ( dealer seems l;last and so does 2 others that I have asked about this issue ).
What would happen if you just close off the vent holes completely with say duck tape ?
 

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Ive had mine for over three months now and 8,000KM and I haven't encountered this yet.
 

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I think this is why the back bumper has this slight misalignment with the body which bugs me (not noticeable at first glance but can be seen when looking closely). They must have fixed this while it was on the lot. And the people at the car dealership cannot align bumpers like robots do.
Anyways bought the car end of September and never heard this thumping sound so far.

I remember asking the saleman about the whether the car was fixed for the driveshaft recall that i read before taking the car. He told me they fix all cars on the lot promptly if a recall or notice happens. Thus i suspect those of us who took possesion of our vehicles after this notice may not suffer from it
 
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