I have a 2006 Chevy Trailblazer and the past few months, there is a whistling noise when I accelerate but only when the air conditioner is on. Now I have noticed that the air is not that cold. Would you know what the problem is?
Perhaps a leak. I think you need to see a shop that does automotive AC work to get a definitive diagnosis. It takes specialized equipment and expertise to repair AC systems.
Remove the belt from the compressor pulley.
Now try wiggling the pulley. If the pulley wiggles the pulley bearing is starting to fail.