2005 trailblazer a/c?

[67chevy2wd]

I have a 2005 trailblazer and the a/c doesn't work at an idle. I checked the pressures and the low side was 45psi and the high side was 175psi. I thought maybe the compressor was bad so I bought a reman and put it on today. I did a half hour vacuum and then tried to charge it. It wouldn't really suck the freon in very well. I got 2lbs in it (takes 2.8lbs) and the compressor started locking up? The pressures were 45psi and 200psi. The low side still won't come down. I am at a loss now and hoping someone else has some advice. I don't want to pay the dealership to fix this but I might have to.