To become a licensed Journeyman or Master Air Conditioning and Refrigeration Mechanical Unlimited Contractor in the District of Columbia, you are required to pass an open-book exam. We offer the books, tabs, and a fully online and inclusive educational course to prepare you to sit for the D.C. Journeyman or Master Air Conditioning and Refrigeration Mechanical Unlimited Contractor exam. @HomePrep is a National Leader in online education. With over 100,000 satisfied students and a course catalog of over 1,000 classes, we are here to help you – Invest in Yourself. The highlighting guides and quizzes are designed to familiarize students with testing materials. We do not provide students with exact test questions, as the state does not release this information.