I am reviewing a commercial refrigerator which I cannot control low because I cannot open the valve because it is deformed. And I have to measure x high and it is at 80psi, but when the compressor starts it does not rise, it stays stuck at 80psi. This refrigerator works with an expansion valve and the forcer must change it because it does not work. Any idea how I can measure the low? And why doesn't the pipe even perspire? In the evaporator it is heard how gas circulates, but very little