Norm Christopherson has been involved in the HVAC and refrigeration industry since 1970 and has taught at San Jose City College in California for 18-years. He has custom designed and delivered training courses for IBM, Coca Cola, Ford Motor Company, Advanced Micro Devices, Lockheed Martin, Loral Aerospace, state government agencies and numerous HVAC contractors. He has been a national and local speaker for the Refrigeration Service Engineer?s Society and continues to lecture and present technical seminars nationally. Norm is published regularly in HVAC technical magazines and is the author of several books for the heating and cooling professional. He has successfully owned and operated his own HVAC installation and service business specializing in solving system problems. Norm is a Senior Training specialist for York UPG International where he develops and presents York training materials.Christopherson, Norm is the author of 'Dewalt HVAC Technician Certification Exam Guide', published 2005 under ISBN 9780977000333 and ISBN 0977000338.