I have a 2010 journey sxt. And I just replaced a radiator. I had to charge the ac system back up and I don't know if I over charge or under charged the system. I hearing a hissing noise when the ac is on. It comes and goes and last for about five seconds.When I turn on the rear and front on max I don't hear the noise. My ac really blows cold when the recirculation button is pushed. Can someone with this hissing

 

Put a set of gauges on it and read the pressures.

 

I used the gauge adapter from Walmart and it bounce back and forth between 40psi on low side and in the dander zone on hi side. Should read it with all the vents open and on max front and rear? I only put in two 12oz cans of freon. Is that enough?