My new Honda CRV 2013 has an intermittent hissing sound that comes from the AC. It has had this problem since day 1, but Honda refuses to do anything about it because they say that the car is functioning normally. The hiss is intermittent, occurring about once every 15 to 30 seconds, possibly whenever the compressor comes on. It can be quiet some times and louder at others, but I can clearly hear it even if I have the radio is on. I tried other new CRVs at the dealership and I didn't hear this noise. Any thoughts?

Totally normal. It's the sound of the compressed freon (liquid) going through the Thermostatic Expansion Valve (TXV), which is being converted to a gas. This is what cools down the evaporator coil.