Hello, if the compressor was welded or "connected", you have to desolder it, take out the filter and replace it. Separate low line and altar line to clean with R141b and remove residues from the components of R410a and the synthetic oil used by the old compressor. Even more ... I insist on cleaning, if the previous compressor burned. Then, it can be swept with nitrogen and weld the compressor, then deep vacuum and load. The 5 ton compressor = 5hp is expensive to skip the cleaning and filter change steps. And the vacuum also, to eliminate the little residue that has been left of the cleaning and also, to ensure the tightness. It is at least 5 kilos of R22 that carries that equipment, and does not give to throw them into the atmosphere for a leak and also worth money.The pressure depends on the ambient temperature, a serious relationship: 30 C ° 60 psi ... greetings ... comment