I'm with jblackburn on this one......high side A/C pressure is in the 200psi range, low side in the 30psi range and the pressures will equalize after shutoff......takes about a minute or two.

They use a tiny diameter oriface instead of a expansion valve.....those disappeared from cars in the eighties......same concept though.

Rob

 

Noticed the buzz today for the first time after 12k miles. Car is a stick, a/c was not on at all today, temps in the 60's. It lasted less than a minute but hard to ignore in my garage. For now, I will consider it a "feature" sort of like my steering "stiction" which has disappeared at least temporarily.

 

Noticed the buzz today for the first time after 12k miles. Car is a stick, a/c was not on at all today, temps in the 60's. It lasted less than a minute but hard to ignore in my garage. For now, I will consider it a "feature" sort of like my steering "stiction" which has disappeared at least temporarily.

fftopic: So I'm not the only person who's noticed the steering "stiction" has lessoned over time. Mine's still there but not nearly as much.

 

Don't know why this would be confusing to anybody. The auxiliary water pump is mounted right up by the head to the left of the turbo, as you look at the engine. It is the black thing that the radiator hose is connected to. It runs for whatever amoount of time to keep the turbo from coking oil in the bearings. Not a big deal unless, later on down the line we find that it is a problem. I had one on a Dodge durango for aft heating that let loose. But lets face it: It was a dodge. (Really does not matter, I am sure it was a vendor supplied part, much like this one probably is)

 

Pretty confident you are right on this. That's exactly where the noise was coming from the one time I heard it. Oddly, it was after my wife drove the car and I've never heard it do that when I drive it(every day).

 

Mine has made this noise two maybe three times. Twice I know for sure. I have a 2013 eco manual. Haven't really looked into it until I saw this thread. Now I feel like I have to know what it is. Haha

 

I've had the sound come back every now and then. After much research on this thread and others, I have concluded it's just a normal thing lol probably cycling coolant or oil to our turbo to cool it down. Who knows. It sounds weird, but a ton of us are experiencing it so it must be normal at this point lol

 

I was looking through the owner's manual for my wife's Solara and it mentions a buzzing sound. I wonder if we have the same thing - fuel system evaporative leak test that's performed after the car is shut off.

 

I've heard the Cruze make the evap system test before and it's from the middle/rear of the car.

Want another weird noise? With the ignition on but engine not running, pump the brakes several times. You'll hear a vacuum pump for the brake booster run.


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It is doing a self test for your ABS system. It wont do it all the time...however it should do it frequently.

 

ABS test only happens when you start the engine and hit 12 mph the first time. It's a noticeable "clunk" from the front wheels.


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According to my dealership and a good friend of mine thats what they said it was...becaause i called about it like a month ago and noticed it from when i left the store. Im sticking to what they say since they are the certified mechanics.

 

Ok. But we're talking about different noises. So it's not that.


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well the question i have is, is it a sound that is heard when you tap on the brakes? I want to make sure we are all thinking the same thing here

 

No. You can hear that pump running after shutting the car off too and it's definitely a different noise than we are talking about here.

Link to (that) noise: http://www.youtube.com/watch?v=pJZNwTpipuU


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No. You can hear that pump running after shutting the car off too and it's definitely a different noise than we are talking about here.

Link to (that) noise: http://www.youtube.com/watch?v=pJZNwTpipuU

Hi all,

Since yesterday morning my 2013 ECO 6MT with 4500miles has been making a buzzing noise as well. I knew I had read something about this on the forum here and so checked it out this morning.

For background, I have never heard any buzzing noises before. I only started hearing this since yesterday. It is certainly not the same as the metallic buzz most people report on here and seen in the videos. However, mine matches exactly what jblackburn shows in the video in this post.

I hear it first thing in the morning (cool car in the garage) when I turn the key to ACC. I popped the hood and I could hear it from somewhere near the passenger side engine bay (near the turbo). I don't hear it after turning on the car (possibly because engine is louder). I do hear it though after a drive and switching the car off. I need to go and check again now after the car has cooled down from the drive.

jblackburn or anybody else have any idea about this particular sound that you show in this video?

I am concerned as I have only just started hearing this sound.

Thanks.

 

Oh okay. Yeah im not sure about that sound then. All I know is the one that goes off when you apply the brake, and it does that ABS check or whatever it was that my dealers told me. How does this sound sound exactly?

 

I ended up in this forum after seeking an answer for just this issue. I've had my 2013 Cruze LS 6 spd manual trans for not quite 3 months and I've noticed this buzzing noise twice. The first time I don't recall the outside temps being very hot and I'd been driving for less than 20 minutes. The second time was this past weekend and it was in the 80's outside and we'd been driving for maybe 45 minutes when we shut the engine off. I heard it and asked my husband to come listen - his thought was a fan of some type. At any rate, both times I put the key in the ignition and turned it forward (not fully to start the engine) and then back and the noise stopped.

 

I am having this same issue with my 2012 cruze 1.4T. I don't believe it has anything to do with the turbo since I heard the noise after just backing into the garage from my driveway. Car ran for less than a minute. I do however think it may have something to do with the a/c system since the defrost was on when I heard it. I can also hear the noise when the car is running. If you listen closely you can hear it with the car running and the hood down. Can't believe GM hasn't addressed this issue yet.

 

^^^^^^^^
May not be an issue at all.......since most have heard it (me too) and it doesn't seem to cause any problem, I'm inclined to leave it at.....one of those things.
It would be nice if Chevrolet could give it a definition though......then I could say to myself ' Oh, it's just the 'X' doing its thing.
Kinda along the lines of the ABS self test or the power brake booster playing its little tune in the A.M.

I've wrenched for over 45 years.....over time, you stop fretting over these things.....as long as I can be satisfied there will be no problem down the road.

Rob

 

i wonder if flicking the key on and off to stop the sound is a good or bad thing.

 

I really think it's something running that helps cool the car. My Montana did this and my wife's Toyota has a notice about this very issue in the owners manual.

 

The noise you are all hearing is the security system arming. You can test this by sitting in your car after you have parked and removed the key from the ignition. Once parked, open and close your driver's door while remaining in the car. Using the key fob, lock all doors. At this point if you open a door from the inside prior to the buzzing, the alarm will not sound. Open the door after the buzzing, the alarm will sound. Definitely nothing to do with the turbo as I have an LS and hear this sound all the time.

 

so why has my security system only armed 4 times on hot days with my ac on?

 

I have heard this on my 2012 Cruze as well and like some of you I have cycled the key and it has gone away but not always. A time or two I've had to start it to make it go away. Either way, I would buy the theory of the A/C system to be the most likely. I would say the A/C system is equalizing after being shut off which is completely normal, but some component in these systems on these cars has an inherent noise when pressure is moving "backwards" so to speak as it equalizes, as it would when the system is shut down. The two components that come to mind that might make such a noise would be the expansion valve, as mentioned in other posts, and the compressor or variable displacement control valve on the compressor, as these compressors are of that variable displacement design and could make this noise anomaly as intermittent as everyone and myself have experience since it takes just the right conditions.

 

I too have heard the noise on my 13 ECO MT. I have noticed that I can hear the noise with the engine running if the AC is on low. When the AC system starts you can hear the same buzzing as in the video. When you turn off the AC with the AC control, the noise goes away. On occasion the noise does not go away when the engine is shut off with the AC on.

To my ear as an EE, it sounds like a coil being pulsed at the frequency of the noise. I suspect that something in the AC system is being modulated by the AC controller and on occasion it does not shut down with the engine as you would expect.

It does seem to be comming from the area of the compressor but I have not isolated it to anything specific.

I did notice that if I turn off the AC prior to shutting off the engine it goes away. It may or may not be an issue. I could think of scenerios either way.

I have not tried the various possible combinations very much. It may well be that other interesting things are possible. I'll probably just try to turn off the AC before I stop the engine.

 

Exactly. It's absolutely something in the AC system, and only happens when it has been running.

I'm thinking expansion valve - it's from the right area, but I could be wrong.

 

OK so I asked my Chevy dealer today what that buzzing noise is. They told me that it is the AC compressor. The AC compressor on this car is of the variable displacement type that is electrically controlled.

When the Evaporator gets too cold, the compressor displacement is reduced electronically. This is done instead of cycling the AC clutch. The car still has an AC clutch that is disengaged if the AC is off but it is not used for control.

I find it's most notable with the AC set to cold and the fan speed at minimum. If I increase the fan speed the noise goes away after a few seconds. The noise does fade in and out as you change the fan speed. I believe that the AC control is using PWM control like a FI to adjust the compressor displacement.

As for why the sound continues after turning the car off, they had no comment and I could not get it to do it. My car does do this on occasion but so far I have not figured out any sequence of events to cause it. I would not doubt that just about anything might cause it to stop if it did continue. This might include arming the anti theft system.

Basically they claim it's normal. Bring it back if it gets louder.

I guess I'll monitor the situation

 

Yeah, I was definitely incorrect in my assumption. I never use the AC and the one day I did I heard the noise too.

 

My '13 LT 6spd manual has done this three times. First time I turned the car off with the A/C on. Did what others did and turned key to ON to check idiot lights, saw nothing, then turned the car OFF, and it stopped.

Second time it happened, I was at my hackerspace. Rushed in and grabbed a friend that was there who might be able to pinpoint the location. Couldn't, as the sound slowly faded away.

The third time it happened, I had driven about 45 minutes, but only had the air on about 20 minutes into the trip and turned it off about 10 minutes before arriving. (I only had the air on while driving on the expressway). When I arrived at my destination with the air turned off, the car made the noise. I did the key trick to turn it off. Not sure if that's bad or not.

To the person in post #68 (too lazy to find it and quote it), the reason why it doesn't stay on due to the key turning to position ON then OFF, I'm guessing based on my BS in computer engineering, is that the way they designed the system (if this is normal), is that the ECU looks for a value that is greater (or less than) another, and then turns this solenoid, motor, etc ON for X amount of time (perhaps based on the initial read value). When you turn your key ON then OFF (interrupting the current operation), the ECU reads again, but at this point, the data value it's checking is within the safe threshold, so the solenoid, motor, etc. does not kick back on or stay on. Just my two cents.
The way to prove me wrong is to be able to never get it to come back on after you go back ON to back OFF once you turn your car off, immediately after hearing the sound.

The turbo lube idea was pretty good. But since people with LS Cruzes are saying they hear it to (granted they're hearing the same issue), then it leads me to also believe it is the A/C unit. I have never heard it through the winter, even with defrost on. Only on hot days (I rarely use A/C).

 

If you have the 1.4 the sound is most likely, in English, the car cooling the turbo down. It has an internal system that keeps it from overheating and it makes a high pitched buzz.