Retired registered Professional Engineer (structural). Graduated from The Pensylvania State University with a Bachelor of Architectural Engineering. Navy Nuclear Reactor Operator (Electronics Technician). Over 40 years of DIY, volunteering, or part time working on almost all kinds of home projects (including jacking up a home). I have done HVAC ducting and electrical work but I have never attempted to service the pressurized coolant side of an A/C system.