Weird a.c. problems

Well, I have a 99 p ete 379, and for a while, I was having a rare time where the a.c. would just randomly stop working. Over time, it got worse, till 2 weeks ago, it just didn't work. Made it home, threw a machine on it and it only had 2lbs, 6oz in the whole system. I put in a new orfice tube, accumulator, high pressure switch, and an expansion valve in the sleeper (never had rear air) Now, I know there has to be a leak beings it was that low, but here's the other situation. We sucked it down, left it under vacuum for 30 min, and it held. So, 5 lbs was added as the sticker shows, and it worked great for a day. Next day, it was hit or miss. No real rhyme or reason when it worked or not, but then, every time I'm parked with the fan on, it worked fine. It didn't work more than it worked, but we toughed it out for a few days, till today (from first recharge to today was 8 days). Went to a little shop in Iowa, looked over everything under a blacklight, and nothing was found. Sucked it down and it only sucked out 4lbs, 6 oz.

Jumped the fan switch, and the low pressure switch and both worked. He was lost as to what to do, so he threw 5 lbs back in with more dye and off we went. It worked great the few blocks over to Petro for a quick shower, then we headed out. About 5 miles out of town, it quit again. So, I got ahold of peterbilt in cedar rapids, and they threw their machine on it. With idle at 1000 rpm, the low side was between 50-53 fluctuating with the fan. High side was 175-270ish. They thought it was a little on the low side, so they added another half a pound. Then, it dropped the low side to 37-41. Even then, the air out of the vents wasn't anywhere near as cold as it should be.

They now sucked it down, it pulled out 5.59oz. So it didn't leak out. What's next. I'm so lost. They are gonna pump it up with nitrogen and try and find leaks.

Any help?????

 

Also, I should note, in the last year, the a.c. lines were flushed because my compressor took a crap. So, the system has a new condenser, compressor, oriface tube, accumulator, high pressure switch, and expansion valve.

Also, the sleeper air stops working exactly when the dash air stops. So it's like something is shutting the compressor off.