Air Conditioning hissing noise! GGGRRRR...

I have a 1999 Acura 2.3CL and when ever the temperture gauge or air conditioning is on, there is a hissing noise coming from the passenger side hood area. WHen I turn it off, the noise is gone. It sounds like the air conditioning is decompressing itself and back on again. There is cool air that comes through so I know my air conditioner works. I brought it into the Acura delaership and they said they can not isolate the problem and would have to dig into my air conditioning system to locate it or I just have to live with the problem. Has anyone experienced what I have or have a solution? Not a car knowledge person but was wondering if this is fixable! THANKS!

that's what happen to my accord too

If you are leaking refrigerant it want hiss long, plus it will leak with the air on or not. Could be the expansion valve, at the evaporator, as the refrigerant is metered thru? Maybe the compressor clutch is causing the noise?