Demonstrate understanding of low/high pressure oil systems, split condensing/low ambient controls, refrigerated equipment startup, EMS controls, CO2 refrigeration, new retail store refrigeration startup, air flow characteristics and testing, motor VFD's, all system defrost types, recovery setup, torch setup, compressor operating parameters, conventional refrigeration system layout, and parallel rack system layout, and advanced wiring diagrams. Detect and repair leaks on conventional systems and parallel racks, solder with copper-to-brass and copper to steel, conduct compressor diagnosis and replacements, troubleshoot and repair more complex service calls, check/adjust oil management system and compressor oil level control.