Air conditioning hiss

[texadelphia]

I was driving around yesterday with the air conditioning on and noticed a hissing noise coming from behind the dash every 20 seconds or so. A/C is cold and nothing else seems out of the ordinary, just this hiss. Only had the truck since Saturday so I don't know if this is a normal thing for these, just not something I've noticed on other cars I've owned. Any thoughts?

 

[Devbot]

100% normal. Some (older) cars do it, some didn't. Not so common nowadays since cars are built to be extra quiet