AC noisy?

The AC on my wife's 04 Trailblazer was taking about 1-2 minutes to get cold so we took it to a local shop for inspection. They said there was a block in our system, cleared the blcok, installed a new pressure valve and all seemed well. However, now the air conditioner makes a noise when you first start it that sounds like water boiling, this is inside the car. It subsides after a minute or two, but it is annoying. I took the car back to the local shop and they checked the pressure and fill and said everything was normal and I should give it some time. It still is noisy!

Any ideas!!!!

What was blocked and how did this occur, very unusual diagnosis.

Not certain about the blockage, maybe I didn't pay enough attention. Apparently the pressure valve was not functioning properly and the pressure was too high in the system?

Again, no pressure valve, you need to find out what exactly was done and why for any help.

Do you still get the noise if you turn off the A/C and turn on the heater? If so, it's probably the fan, maybe some hair or debris or leaves got in. On the other, there's a high-low pressure switch for the A/C, which is an item that GM replaced many of in your model year range.

Been on the road! The noise does stop when you shut the air off, so it's definitely in the AC, and I would assume in the AC coolant line. The local shop tested the pressure and it was right on. Maybe some air trapped?