Does the AC compressor have a pressure control valve?

[paramax55]

I have a 2006 X5, 6-speed. It's new to me. The AC compressor won't make a pressure differential - it's not moving refrigerant. The clutch engages.

When the wife's Lexus did this, it was the easiest fix ever - a pressure control valve. One bolt and an electrical plug, that's all. But I don't think these cars have a control valve, do they? I saw a listing for one when I was looking for a compressor, but you see all sorts of crazy stuff on the internet...