My 2002 LS430 started "passing air" a few years ago while it was still under warranty; it hisses rather than gurgles. A tech at the Henessey dealer on PIB said it was normal for the expansion valve to release air. Well, I didn't like their answer since the hissing didn't happen when I got the car used in 2003. I took it to Summit (on Dekalb Industrial Way) off of E Ponce de Leon in Decatur where they specialize in all Japanese makes and models. One of the owners, Mr. Te, drove it with me and he confirmed what the dealer told me. The hiss is annoying but my AC sytem is working fine, knock on wood. Besides Summit, a friend takes his one-of-a-kind IS300 to a service team off of Talley St. just behind the Avondale MARTA station. He's a racing fanatic and his guys do high-performance work. I think it's Spectrum Performance. BTW, I'm a female who tries to understand everything about my car. Anything that doesn't make sense causes me to do research. I don't like it when the dealer's service "advisor" talks down to me because I'm female.