From HVACRInfo site on scroll compressors:
Loud, very loud, relief sound coming from the compressor.
Some model scrolls have an internal pressure relief (IPR) valve. This valve opens at a discharge to suction differential of 375 to 450 psi (R-22) or 550 to 625 psi (R-410A). Check for restrictions in the discharge line, overcharge of refrigerant or a faulty component.
I think what you need is someone who knows what they are doing. Not "Bevis and Butthead".