The focus of this furnace repair guide, is to be a simple and straightforward Furnace Failure Diagnostic manual and basic repair guide. The goal is to direct you quickly and efficiently to diagnose common furnace failures. Each diagnostic will easily provide the likely mechanical failure in your furnace. The diagnostic questions follow a YES or NO answer style, to easily understand and direct you to the potential furnace failure. This manual has been developed for troubleshooting modern 80% efficient furnaces with Hot Surface Ignition. This manual does not cover Spark Ignition or Standing Pilot Furnaces, however most components are similar in all 80% AFUE furnaces. The Manual does not cover 90% Plus AFUE furnaces, due to the complexity of such furnaces, all diagnostics could not be included. If you have a 90% Plus AFUE furnace, this manual may still be helpful if diagnosing common mechanical problems, but may not be sufficient in fully troubleshooting your furnace. It is also important to note, this manual seeks to help troubleshoot basic problems and will not be able to help diagnose very challenging issues, these types of issues are always best left to professionally licensed HVAC Technicians. If you are looking for a manual that provides in depth technical and mechanical details regarding your furnace, this is not the right manual. This manual has been designed to be an easy to understand troubleshooting and repair manual for standard 80% AFUE furnaces. SAFETY NOTE – ALWAYS TURN THE MAIN POWER AND GAS VALVE OFF BEFORE SERVICING ANY HVAC EQUIPMENT. SERIOUS INJURY CAN OCCUR. CARBON MONOXIDE CAN BE A DANGEROUS BYPRODUCT OF AN UNSAFE FURNACE, IT IS CRITCALLY IMPORTANT TO HAVE PROPERLY INSTALLED AND OPERATING CARBON MONOXIDE DETECTORS IN YOUR HOME. This guide’s intention is to provide an understanding of the operation and likely failures of your furnace. It is not intended as a hands-on teaching tool, or aide. All HVAC equipment should be serviced by a licensed HVAC technician. Consult your local, town, city, and state laws, ordinances, and regulations prior to accessing, engaging, troubleshooting, repairing, or servicing any HVAC equipment. Go To http://helpitbroke.com/hire-a-pro/ to find a qualified HVAC Professional to help you fix your problem. We are constantly adding new Pros in locations throughout the United States.