For sale is a New Air Conditioning and Refrigeration Trouble Shooting Calculator. On the front and back side of the guide is a comprehensive chart with categorized symptoms, possible causes and repairs. This is a very useful tool for troubleshooting almost any type of problem. This item is made of thick cardboard stock with metal corner rivets and measures 3.5 inches tall by 7 inches wide. Check out my other HVAC reference guides including superheat calculators, humidity charts and duct sizing charts available in my ebay store while supplies last!