13GSCGvette

Have a 13GS with under 1K miles and notice with the AC on I hear a knocking sound coming from what appears to be the console area by the shifter. Anybody else seen this?

SUB VETTE

Only with the a/c on?

13GSCGvette

yes

michaelinmech

knocking sound


Come IN ??? (somebody had to)

JPJR

YES!

Mine does it too.
I've been searching the forums for HVAC noises, but haven't found what I've been hearing.
I even recorded it on my phone, and I uploaded to YouTube, but have been unable to find the link to my video.

If I shut off the HVAC, it goes away.

To me it sounds like it might be an actuator of some sort that is trying to open and close a vent or something.

Mine's a '13 GS, too.
Noticed it the first week I had it.
It's very noticeable.

JPJR

Sounds like this...

13GSCGvette

That's it! Now what the heck is it I wonder?

z51vett

Could be hose knock on the firewall or one of the shades has torn loss that opens and closes of vents.
z51vett
Doug

JCtx

Man, hope that's not the case, since getting to that stupid box requires dash removal . Having to do that to a brand new car is almost an insult. Good luck OP. And please keep us posted.

ChevyDave

hummm.... question. does the knock speed up or slow down with similiar increase/decrease in fan speed? is there anyway playing with controls to increase/decrease the knock speed?

no matter, i'd get it into a dealership, so its logged as possible later or actual now, warrenty work.

User 2623

Hmmm, I had a related issue which was a high pitched whine when running the A/C or heater which got worse with the fan speed. It was obviously the fan motor. I chose to live with it fearing a disassembly of the dash.

I suspect the knocking sound is similar to the whine in that it has something to do with the fan assembly or the motor itself. I would guess the fan rotar piece needs to be repositoned as it is touching the vent wall or fan guard.

Good luck...

JPJR

On mine, the knock doesn't get faster.
It seems like it starts when the HVAC is trying to change settings (dash vents to floor vents, etc).
It doesn't change with fan speed, but it stops when I shut off the HVAC.

On a possibly related note, I will get airflow from over the top of the dash when it's set to floor.
I noticed cold air was blowing in my face when the HVAC was set to a temp that should have been causing warm air to come from the floor.
I can make that stop by switching to the dash vent setting.

I really hate for them to have to rip my whole dash apart.

13GSCGvette

The knock does not get faster either on mine, however I need to check the airflow as you mentioned. I too hate for them to have to tear up the dash to get to it as well.

JPJR

Anyone else seen this problem yet?
Seems odd two different '13's are experiencing the same thing.
I think there would be at least a few more.

The knocking sound is annoying, but so is the inconsistent HVAC operation.
One time I had the airflow set to dash vents, and nothing came out of them, even with the fan all the way up.
All of it was coming out of the defrost vents.
I had to shut the HVAC system off, then back on.
Also, if it's a sunny day, but cool out, the system will be in bi-mode (floor and dash vents). But it comes out of the defrost vents, not the dash vents.

I've learned to live with all of this.
I'm scheduling a service visit before the Bash, but I'm not sure I want the dealer ripping into my dash.
Maybe better to ask at one of the C6 troubleshooting sessions at the Bash.

truckplay

does the noise get better or worse if you change the temp ? or if you change from floor to dash? if it does then 1 of the motors that regulates that action is loose or binding up. they are called mode door actuators.

96GS#007

My '13 definitely does not make a sound like that. The dash on these cars is pretty easy to take apart, so you might consider pulling it apart to take a look without the console and dash pad in place. It may help you to narrow things down a bit.

JPJR

I'm pretty sure the sound is coming when it's trying to change airflow direction.
Like it's trying to close the floor vents and open the dash ones, but the actuator, is stripped, (or binding) and it can't completely close or open a door...so it keeps trying.
When I shut off the HVAC, you can hear it immediately stop.

I guess if getting into the dash is not that big of a deal, I'll let my local dealer look at it.

AORoads

that sound is familiar. not on my vette, but on another car it was the electronic acutators/sensors. and they do move the "doors" that route the air flow.

in this other car, it looks like a sealed piece of plastic about 2.5x2.5 by about 3/4" thick. mine didn't require disassembly of the dash, but there is a third one in there that does. we would be talking intensive labor charges.

since yours are new cars, it's a 3/36 thing if that's what it is.

ChevyDave

i had saved this for other reasons. of NO value for ya, but it does show all the parts in that dang thing!! noise caused in here somewhere, i wouldnt want to be the one to tear into it.. lol

JPJR

Thanks for the info, all!
I'm scheduling an appt to have it looked at.

That's one of the reasons I traded my '06 for a new one...the warranty.
Might as well take advantage of it while it's there!

I'll post the results...