Ac compressor squeal?

[71C10Guy]

Okay, so I have completely redone my AC system. My low pressure switch does not work, and really none of the circuitry to the compressor works. I have it wired to a switch on my dash to engage the magnetic clutch. Everything is brand new.

So when I turn my compressor on at idle it will run fine for about 30 seconds before it starts seizing. The belt slips on the compressor pulley and makes a horrible squealing noise. This also practically stops my water pump and fan. Once it starts it will not stop until I disengage the clutch. If I am not idling, even if it is just a hundred rpm over idle, the compressor immediately seizes and squeals.

I cannot figure this out. Everything is new including lines, the compressor came with oil in it and I put more oil in because I had a leak that let out about half of the original freon. I have retightened the belt twice, one person pulling their whole body weight on the compressor and the other tightening bolts. I don't see how I can have dirt in my freon, and the belt definitely isn't loose.

The only plausible thing I can think of is the high side of the gauge I used is leaking so I did not hook it up, therefore I do not know what the high side is when running. Low side is at 30 when running. I am running R134a.