[Chester Stone]

I have a few questions and comments re the auxiliary air compressors. My 12v was not working, but I also had only a 10amp fuse. Replaced it with a 15, and it blew also. Seems to be holding with a 20 amp fuse. I have noticed that the 12v compressor adds air faster that the 120v compressor. However, I cannot figure out a way to determine the shut off pressure for each of them. Attached is a photo of the pressure control valve at the location on the 12v compressor. I assume that the yellow control knob controls the air pressure leaving the tank and going to the various units needing air. The valve is set now at about 55 lbs. I can adjust it to lower setting, but when I try to adjust it above 60 lbs. air escapes. Now for my questions. Is my assumption on the control valve correct, and how can i determine the shut down pressure for each of the compressors? I expect I can set the shut down by adjusting the springs in the grey pressure switches. The 120v compressor runs way past 55 lbs. and I am concerned that the shutdown is too high.