I concur with primetimex, sounds like the Tx valve which is expensive and should be fixed under warranty.Honda will claim it's a normal operating noise which is rubbish and not befitting of a car which is supposed to be best in class. I have owned old mazda 626's and a Mitsubishi Mirage which had a/c systems that were reliable and QUIET.....go figure.

I eliminated my noise by selling the car and getting a Lexus !

Good luck everyone !!