Whistling noise when A/C is on

[fumble]

So I recently started hearing a whistling noise coming from my engine compartment of my Silverado. I noticed it only happens when my A/C is on. When off, it doesn't do it. The whistling gets louder when I step on the gas. At idle you don't hear a thing. I searched and couldn't come up with anything.

Any help would be greatly appreciated!

 

Thanks,

Dan

[Bad Bowtie2]

I would recommend removing your serp. belt & checking out the tensioner & the idler pulley under it for wear.

[fumble]

I would recommend removing your serp. belt & checking out the tensioner & the idler pulley under it for wear.

 

Wouldn't that be more of a loud squeal rather than a whistle. I'll give it a shot, but I guess I figured it sounded more like air leak, but just have not idea where to look. Thanks!

[nickvrebel]

My 2003 had a little whistle to it, it started within the first few hundred miles and still did it 8X,XXX miles later, never had a problem and didn't bother me enough to look

 

you could inspect the a/c belt (the small one under the serpentine) for wear - there is not tensioner on the A/C belt for a 2008, it's a "stretch to fit" belt. The tensioner on the serpentine belt wouldn't have anything to do with this.

Edited July 24, 2013 by NickV

[Bad Bowtie2]

How long have you owned this truck?

 

Stock air box & intake system??

 

"NickV" is correct too in stating the ac compressor has it's own serp belt. But no tensioner like the 1999 1/2-2007 1/2 trucks had. It's worth an inspection too while your there looking...

Edited July 24, 2013 by Bad Bowtie2

[bbond]

So I recently started hearing a whistling noise coming from my engine compartment of my Silverado. I noticed it only happens when my A/C is on. When off, it doesn't do it. The whistling gets louder when I step on the gas. At idle you don't hear a thing. I searched and couldn't come up with anything.

Any help would be greatly appreciated!

 

Thanks,

Dan

interested to know what happened

[Skip Jarvis]

I had the same problem,  Intermittent whistling when on A/C.  I noticed the whistling would sound when the compressor engaged, but then fade out while the compressor continued engaged,  Whistle, no whistle, whistle, no whistle.  I took it to a  repair shop where they said it was down a little on freon, that they changed my fan clutch, and charged the system back up.  They admitted that they had no idea what the whistle was.  Yes, I listened to it on  the way home, very disappointed.  I began to notice that the air from the vents would quickly cool when the compressor engaged and while it was making the whistling sound, but when the whistling stopped, you could feel the temperature at the vent rising quickly.  It began to fail to be able to cool the cab.

I decided to take it to my local dealer, Wes Haney Chevrolet in Live Oak, Florida.  The service manager drove it and admitted he had never heard a whistle like that before.  Here is what they did.  They evacuated the entire system and checked it for leaks.  None found.  They then recharged it by the weight of the freon, not the pressure in the system.  They advised that it took about a half pound more of freon than it had in it.   WHISTLE IS NOW GONE!!!!  A/C blowing cold.  The truck has 176,000 miles on it and they advised that the compressor is getting along in years, but that they could not justify replacing it yet while everything is working fine.  

My truck is a 2004 Chevrolet Silverado Z71 with 176,000 miles.  Maybe this information might solve your problem.

[NARDA1]

I had a similar problem. System was slightly low on freon, I was also getting vapor coming out of the dash vents. System was refilled and noise went away for a while but returned. Further inspection found a pinhole leak in the condensor. Replaced condensor and refilled system. Problem solved, no issues for over a year. 

 

When I put the claim in to the extended warranty company they indicated that the leak in the condensor was a common problem with these trucks.

[Sierra89]

I just has an similar issue. When the ac was on I would hear an intermittent whistle. I had the system checked and it was low. It was purged and refilled with the proper refrigerant and works great now with no issue. 

 

As a side note, mine was also blowing condensation out of the vents. Apparently who ever topped up the system before I owned it used the wrong refrigerant and broke one of the pressure ports, which was causing the condensation.