Weird repeating noise when A/C on
 

I have an 09 accord V6 and whenever my A/C is on and the vehicle is in motion I will hear a "hiss" type noise that lasts about a second. It occurs every minute or so when driving. I've had it checked out by the dealer and there's no leaks and they say everything is working fine but this noise wasn't always there. Also I test drove a different accord but it didn't have this noise so I know its not normal. The tech refused to go on a test drive with me in my car so now I have to wait for the manager to come back. I was wondering if you guys have heard of anything similar so I can get this resolved.

Where is the hiss noise coming from?

Its coming from the dash area.

My first thought is the normal sound of refrigerant spraying into the evaporator core. Since the noise "wasn't always there" I wonder if some soundproofing material has come loose from around the ventilation ducts??

Maybe a vacume hose has popped off it's place?
Check vacume hoses under the dash...