TroyStudio Vibration Damping Mat, 10 pcs 15.7 x 9 x 0.08 Inches Self-Adhesive Sound Deadening Sheets, Aluminum Foil Noise Dampening Panels for Vent, Duct Wrap, Pipes, Engine, Water Pump, Audio, Car

UPDATE!!! For those who said there is not way to dampen the noise, I found these deadening sheets on Amazon and wrapped my copper refrigerant ac line with it and there’s virtually no more of that hissing sound! Hope this can help someone else. https://a.co/d/0g9Zi0bM

UPDATE- for those saying you can’t dampen this sound. I found this: https://a.co/d/0fsv137m Wrapped a few strips around the copper line and the hissing sound is virtually gone!!