[jas32]

Own a 2007 versa. The ac makes a hissing sound when turned on. It only blows regular air. What could be the problem? What would it cost to repair?

Jimmy, you have to give us more clues here.

As this link shows, the problem can be one of a few things.
5 Ways to Diagnose a Non Working Air Conditioning in a Car

It can be as simple as needing a charge, or bad as a shot compressor, evaporator or condenser. Nothing unique about the Versa AC system as all car AC systems are virtually identical. As far as cost, it depends on what is wrong.