Active in the HVACR industry since the 1950s, Bill Johnson graduated in gas fuel technology and refrigeration from Southern Technical Institute, a branch of Georgia Tech (now Southern Polytechnic Institute). He taught at Coosa Valley Vocational & Technical Institute for four years. He moved on to become service manager for Layne Trane. He taught for 15 years at Central Piedmont Community College, part of this time as program director. He had his own business for five years doing installation and service work. Now retired, he is the author of Practical Heating Technology and Practical Cooling Technology, and continues as a co-author of Refrigeration & Air Conditioning Technology, all published by Delmar Cengage Learning. The articles in this eBook are a collection focused on various aspects of HVAC troubleshooting.