# High pitched noise under the hood.



## Jlirajr (Jan 11, 2013)

Just got my cruze Penelope a few weeks back, it's my first new car so I'm excited. So long story short I park my car turn off the engine and walk away. I hear a faint high pitched sound, open the hood and there it is. Not sure if its just the fan kicking in but it sounds like someone is letting air out slowly from a ballon. Any ideas?


----------



## obermd (Mar 3, 2012)

Welcome to CruzeTalk and congrats on Penelope. You're hearing the same sound a lot of other people have reported. Other than somewhat annoying it doesn't appear to hurt anything. There are several theories as to what it is but no one seems to be able to isolate the source of this noise.


----------



## Christrit (Jun 23, 2012)

I had the problem also... But haven't heard it since the summer time... (knock on wood)...


----------



## cruze01 (Mar 25, 2011)

I have heard it in warmer weather. I think its the freon in the A/C system bleeding down. You may also hear it in cold weather as the A/C runs when you have the HVAC controls on defrost.


----------



## jblackburn (Apr 14, 2012)

AC Expansion valve. 


Sent from my iPhone using AutoGuide.com App


----------



## Jlirajr (Jan 11, 2013)

Now that you mention it I was running the ac before I heard the noise.


----------



## iCruze2 (Dec 16, 2011)

Mine does it too. I just thought it was my ballast's humming(which is a similar sound). It is annoying when outside of the car, lol


----------



## firehawk618 (Feb 24, 2013)

Mine was doing this exact same thing when I got home today. I pinpointed it to the a/c compressor. I flipped the key on and back off and it instantly quit. I was not running my a/c.


----------



## Mick (Dec 31, 2011)

Another Penelope.

Can you post a video? I'm betting a dollar it's the AC compressor.
Try turning the AC on when you hear to see if it goes away or changes pitch.


----------



## cornbreesha (Apr 29, 2012)

Mine did that in the summer, but hasn't happened during any cold weather.


----------



## Aussie SRi-V (Aug 25, 2012)

My money is on the Transmission Control Module.. You are hearing the sound of a high frequency solenoid.
Try this. 
When the car has been sitting switched of for about 5 mins, open the car door. 
You should hear the sound in the engine bay between 14-16 sec later. It should last about 6 sec
Close the door the same cycle will be repeated.


----------



## Chevy Customer Care (Oct 29, 2011)

*firehawk618,* 



If you continue to be concerned with this noise, we definitely recommend that you have your dealership look into this for you just to be sure. If you have any questions or require further assistance please feel free to private message us.

Ashley (assisting Stacy)
Chevy Customer Service


----------



## AlgUSF123 (Feb 19, 2013)

I hear this noise in my vehicle, and I believe has something to do with recirculating oil through the turbo. I only really hear it when I have been driving it hard.


----------



## rsalinas (Mar 25, 2013)

Mine does it when I click the key to unlock it.


----------

