I purchased my 2000 vette about 8 months ago and since then whenever I turn on my car behind the instrument cluster it sounds like air is being sucked in like an intake. Before it would it only last about 5-10 seconds only when the engine was cold. But lately it does almost every time cold or warm. When the engine is cold the noise goes on until the engine warms up. But when the engine is warm it stays on until I start driving and get to about third gear on the first take off. As I shift through the gears the sound lessons but increase again when shifting between gears until I get to third and then it's gone until I turn off the engine and start it again. I don't what this is, if it's bad, or where to even start to determine what's making this noise. Anyone experiencing this or know a fix for it?

 

Have you popped the hood to see if the sound is there? Maybe a vacuum leak? Can you post a video?

 

Yeah I've opened the hood and there's no sound coming there. I can only hear it behind the cluster. I'll post up a video tonight but I don't think it's a vacuum leak but it eventually goes away once I get into about third gear maybe fourth.

 

 

WELL,,,,,,, I didn't really hear any weird noises in your Vid.

That being said, ALL of the HVAC DAMPER DOORS are vacuum controlled. You have a Vacuum Servo for all the dampers. The vacuum is controlled from outputs of the HVAC Control Unit and they operate small electronic solenoids in the vacuum control module.

When you first turn on the car, the vacuum may have leaked out and the dampers are trying to reposition them selves to the correct position.

You need to see if you are losing vacuum inside the vacuum reservoir that lives inside the passengers fender well. The vacuum reservoir canister has a check valve that keeps vacuum inside it when the engine is off.

See if you can change the damper position/s and see if the noise changes.

Your going to ask (What dampers) LOL! Dampers control: Where the air comes out i.e. feet, center console, defrost and or if you get recirculation air of outside air.

Take it out of ANTO and change the dampers around to make sure that they function properly.

Here are some pictures of the servos, vinyl vacuum tubing and that reservoir:

VACUUM CONTROL Module:



DAMPER SERVO:




VACUUM VENT SILENCER:

 

Looks like I have a project for the weekend lol car is in the shop right now, crankshaft pulley bolt came loose. I'll post and update once I finish these steps. Thanks Bill

 

I have a similar noise—it's very faint. But nothing seems mechanically wrong, so I don't worry about it.

 

Might be the air pump...?

 

The one under the left headlight? Maybe, but it sounds a lot closer, like it's under the dash.

 

The passenger side air pump tube runs to the back of the engine and is really tough to reach, even if you remove the intake manifold.
The driver side is easier to deal with. Not sure what else to suggest, but someone on the forum will know more and have more to say than me.

 

Yeah, but the noise sounds like it's coming from the back of the instrument panel, not the passenger side. Besides, if there was a leak, I'd probably be getting a P0410 code (BTDT).