ProStarBrakes

I been driving a 2012 Cascadia for about 3 months now, and it leaks air out a thin air line (pressure release valve?) under the motor every 10 to 15 seconds. Wasn't doing it until a few days ago. Company shop says it's normal. They claim to have serviced it with a kit of some sort anyway (doubt it). It got louder, so I called maintenance dept. and they didn't seem to think it was an issue. WTF? I know the damn compressor's got to be overworking itself. It doesn't "woosh" like it's supposed to, it just bleeds out the governor or whatever that line is. Anyway, sounds like the same thing this guy is talking about. I've read some stories online, and haven't really found a real solution. Doesn't seem like the problem ever gets fixed, or maybe it isn't a problem, but rather a condition in with some air dryers decide to work under out of the blue. I know what started it with mine though. I hooked to this trailer the other day, and immediately after, this started going on. So i checked to see if there was a blow out valve (or air release valve) on the air tank under the trailer, and it was, I bleed it for a good couple minutes while it blew water and rust. So that got into the trucks air system for sure, as the tank on it bleeds rust residue now sometimes. I also tried plugging the little air vent line where the thing keeps purging the air out of for a sec and water started draining out the bottom of the air dryer, so i quickly unplugged the line before i fucked it up. Didn't have a clue what I was doing, but there was a thread online that recommended something similar to force the diaphragm to the blow off valve to close or whatever. Just giving my story for the record. Going to have a company shop look at it again when they route me past one again. I don't care what they say, it ain't supposed to be doing that. It's just too loud, and there's got to be a reason why it doesn't "whoosh" like all the other trucks do. The mechanic and the guy at the office both say it's supposed to purge after it gets to 125 psi. Well no fuckin' shit, but why would the compressor constantly be running when the tanks are full, or why would it keep cycling?