Air keeps purging every 30 seconds/oil question

So the other day I noticed that my 2011 international prostar was purging about every 30 to 45 seconds and right before the clutch fan will kick in for some reason to push the compressor to build air and it will kick at 120-125 psi. Today I changed the air dryer and it’s still doing it tomorrow I’m buying a governor but I honestly think it’s the unloader valve on the compressor, like I said I build air like normal and I can cut my truck off and hold the brake down for minutes without losing air it’s so annoying any advice. Not to mention I replaced the clutch fan literally 3 months ago. Also I noticed sometimes my truck idles at like 15-20 psi and runs from 35-38 psi is that Normal for an isx cummins... ? Thanks guys my first truck I own and I need her to last for a while...

 

So I replaced both Nd no more kicking every 10 seconds but Now my primary and secondary air pressure gauges are bouncing around. I have air pressure the governor kicks in and seems to be working fine, yet the gauges , not at the same time will go up in pressure to alarm state then back to normal or swing the opposite way....I need help my body controller fuse is fine...