From inside (document excerpt):
58UHV, 58UXV 2-Stage, Variable-Speed Gas Furnaces Service and Maintenance Instructions For Sizes 060-120, Series 100 NOTE: Read the entire instruction manual before performing any service or maintenance. This symbol indicates a change since the last issue. These procedures are for size 60,000 through 120,000 Btuh units. Index Page SAFETY CONSIDERATIONS .1 ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS PROCEDURE .2 CARE AND MAINTENANCE 2-5 Air Filter Arrangement 2-3 Blower Motor and Wheel 3-4 Cleaning Heat Exchanger 4-5 Electrical Controls and Wiring .5 Troubleshooting 5 Application Wiring Diagrams 6 Unit Wiring Diagram 7 Service Label 8 Troubleshooting Guide .9 SAFETY CONSIDERATIONS Installing and servicing heating equipment can be hazardous due to gas and electrical components.
Only trained and qualified personnel should install, repair, or service heating equipment. Untrained personnel can perform basic maintenance functions such as cleaning and replacing air filters. All other operations must be performed by trained service personnel. When working on heating equipment, observe precautions in the literature, tags, and labels attached to or shipped with the unit and other safety precautions that may apply. all safety codes. In the United States, follow all safety codes including the National Fuel Gas Code NFPA No. 541992/ANSI Z223.1-1992. In Canada, refer to the current edition of the National Standard of Canada CAN/CGA-B149.1- and .2-M95 Natural Gas and Propane Gas Installation Codes. Wear safety glasses and work gloves. Have fire extinguisher available during start-up and adjustment procedures and service calls. Recognize safety information. This is the safety-alert symbol. When you see this symbol on the furnace and in instructions or manuals, be alert to the potential for personal injury. Understand the signal words DANGER, WARNING, and CAUTION. These words are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies a hazard which could result in personal injury or death. CAUTION is used to identify unsafe practices which would result in minor personal injury or product and property damage.