Electrical Wiring Diagrams for Air Conditioning Systems Electrical Wiring Diagrams for Air Conditioning Systems – Part One 3- Types of Electrical Wiring Diagrams For Air Conditioning Systems. There are three basic types of wiring diagrams used in the HVAC/R industry today, which are: The Ladder Diagram, The Line Diagram, BASIC ELECTRICITY FOR HVACR TECHNICIANS | Contracting Business Types of Wiring Diagrams. There are three basic types of wiring diagrams used in the HVACR industry today. The first, and most common, is the ladder diagram. From this point forward, ladder diagrams will be referred to as “schematic” diagrams, or “schematics.” A typical schematic of a packaged air conditioner is shown in Figure 1.