In 2002, Jason Obrzut graduated from the HVAC Technical Institute in Chicago, kick-starting an accomplished career in the HVAC Industry. Jason began working as a service technician and, within a short time, became an installation supervisor, and ultimately a business owner. While working during the day, he returned to the HVAC Technical Institute as a part-time, evening instructor. Teaching quickly became his passion, and he scaled back on working in the field to focus on teaching full time. While teaching, Jason developed, wrote, and implemented the curriculum that is currently being taught at the school. His dedication to his students and the institution was evident and he soon became the school s director of education and lead HVAC/R instructor. In 2016, The ACHR News recognized Jason as one of the Top 40 Under 40 in the HVAC industry. He is affiliated with numerous HVAC industry organizations, including Refrigeration Service Engineers Society (RSES), the ESCO Group, and HVAC Excellence. At HVAC Excellence s 2016 National HVAC Educators and Trainers Conference (NHETC), Jason participated in the first annual Teachers-N-Trainers (TnT) competition and took first place in a field of over 60 participants. Jason is one of only 125 instructors nationwide who have held the title of Certified Master HVAC/R Educator (CMHE), and he holds Certified Subject Matter Educator (CSME) certificates from the ESCO Group. Jason has recently accepted a full-time position with the ESCO Institute, an industry partner of Cengage, where he will be taking on a role as part of the content development team to help improve the quality of HVAC/R education and training. Bill Whitman contributed a wealth of academic expertise as well as industry knowledge to this book. Mr. Whitman graduated from Keene State College in Keene, New Hampshire with a bachelor s degree in Industrial Education. He received his master s degree in School Administration from St. Michael s College in Winooski, Vermont. After instructing drafting courses for three years, Mr. Whitman became the Director of Vocational Education for the Burlington Public Schools in Burlington, Vermont, a position he held for eight years. He spent five years as the Associate Director of Trident Technical College in Charleston, South Carolina. Mr. Whitman was the head of the Department of Industry for Central Piedmont Community College in Charlotte, North Carolina, for 18 years. Since entering the HVAC industry in 1980, Eugene has taken on many roles ranging from field technician and system designer to company owner, teacher, administrator, consultant and author. Eugene is currently the Director of Technical Education and Standards at the ESCO Institute. Eugene has twenty-five years of teaching experience and has taught air conditioning and refrigeration at many institutions including high school vocational programs, proprietary post-secondary institutions, and community colleges. In December of 2015, Eugene retired from his tenured teaching position at Suffolk County Community College, in Brentwood, New York, to join the ESCO Group and relocate to Southern California. Eugene earned his dual Bachelors Degree from The City College of New York (New York, NY) and his Masters of Science degree from Stony Brook University, (Stony Brook, NY) where he specialized in Energy and Environmental Systems, studying renewable and sustainable energy sources such as wind, solar, geothermal, biomass, and hydropower. He earned his Certified Master HVAC/R Educator (CMHE) credential from HVAC Excellence and the ESCO Group in 2010. Eugene also carries ASHRAE s BEAP credential, which classifies Eugene as a Building Energy Assessment Professional. He is also an active member of many industry societies. Eugene has served as the subject matter expert on more than fifteen HVAC-related educational projects. His most notable work is Cengage Learning s Refrigeration and Air Conditioning Technology title, which is now entering its 9th Edition (2021). This book is used in more than 1,000 schools both in this country and abroad to help individuals master the skills they need to install, service, troubleshoot, and design HVAC/R equipment. John Tomczyk received his associates degree in refrigeration, heating, and air-conditioning technology from Ferris State University in Big Rapids, Michigan; his bachelor s degree in mechanical engineering from Michigan State University in East Lansing, Michigan; and his master s degree in education from Ferris State University. Mr. Tomczyk has worked in refrigeration, heating, and air conditioning service and technical writing consultation for both the academic and industrial fields for numerous years -- enabling him to bring a wealth of experience to this text. His technical articles have been featured in many HVACR magazines and journals. Mr. Tomczyk is also the author of TROUBLESHOOTING AND SERVICING MODERN AIR CONDITIONING AND REFRIGERATION SYSTEMS. Mr. Tomczyk has 29 years of teaching experience at the Refrigeration, Heating, and Air-Conditioning Technology program at Ferris State University and is a member of many HVAC/R trade organizations. Now retired, Bill Johnson has taught heating, air conditioning, and refrigeration for more than two decades in various technical colleges and factory schools. A graduate of Southern Technical Institute, a branch of Georgia Tech in Atlanta, he has also served as service manager for a major manufacturer for six years. Mr. Johnson owned his own HVAC/R business for 10 years and has been a member of the Refrigeration Service Engineers Society and the American Society of Heating Refrigerating Air Conditioning Engineers. His authoring credits include three major textbooks on the market today as well as their ancillary materials. He has also written monthly articles--BTU Buddy--that are available online.