A/C cooling not working correctly?

The exact reading is 45/190 (pressure for ac) also the air seems to have a mind of its own its ice cold on minute an not so cold the next, I am exspecting the ambient temp sensor today, an tec says that we live in g.A an it is very hot an humid an that may b the reason for the hirer pressure reading. Thanks in advance!

Can u please answer my last question, also I put the ambient temp sensor in an air seems good cadillac is just differant to me cause air goes on an off even if its on 60 im used to the air staying on full blast in older cars but in the caddi its all temp controlled so it will cut off when it reaches a certain temp am I right? Other then that the air is very cold and the back air is cold also.