A cryoablation system has a gas source which provides a working nitrogen gas at room temperature and at a constant set pressure, a liquid generator which is coupled to the gas source to receive the working gas, and which then generates a working cryogen fluid, and a catheter coupled to the liquid generator for receiving the working cryogen, the catheter having a distal section having a freezing element which delivers the working cryogen to a treatment location, the catheter also having a balloon positioned adjacent the distal section.