There should be a chart on the can for pressure vs. ambient temp. The gauge can be in the green, but, still be low.....

 

When we were on our trip two weeks ago we did hear a noise that sounded like a truck dumping air, then the AC seemed to work better for a little while. I was thinking it might be over pressured???
I really think it's possessed.

 

Does water drip steadily from it when the AC is running?

I don't believe there is freeze sensor. Usually freeze sensors are only found on vehicles with automatic temperature control units.

 

Yes it drips water and a lot of it and I can feel air from the drain also so I don't think its a drainage issue.