Air Release Noise With Ac On

[snooft]

I have a 2002 GMC Sierra with 100k and with the AC switch on every once and a while I will get an air release noise from under the truck. It used to be once a trip now it is becoming more and more frequent. My last trip it was happening every 30 seconds or so. The air is still working and blowing cold. With the AC off that noise never happens. Thanks for the help.

[txab]

Will it do it at idle? If needed have someone rev the engine and try and track the sound down. I would think it would be clutch related or belt related.

[bill190]

If it will do this when in park, set the parking brake and chock the wheels, then use an empty paper towel roller. Place one end to your ear and point the other different directions to locate the noise.

 

Or a longer tube would be a gift wrapping paper tube.

 

Of if it only does it while driving, try placing a vacuum cleaner hose in different spots.

 

Then if you don't know what it is that is making the noise, maybe you could post a picture?