Performed ac Diagnostic 19 yr system. Found system appearing to be low on r22 refrigerant. System is 61ozs. System will need close to 3 lbs of r22 refrigerant. Refrigerant went somewhere might be a good idea to inject system with if dye to find leak. Charged system today, will return Monday and dye system then. System charged, well went from 0/125 to 62/172.