Furnace Fan Relay Wiring Diagram | Free Wiring Diagram Collection of furnace fan relay wiring diagram. A wiring diagram is a streamlined conventional pictorial depiction of an electrical circuit. It reveals the elements of the circuit as simplified shapes, and also the power and signal connections in between the devices. Videos of furnace relay wiring Click to view on YouTube4:07HVAC Relays & Fan limit switch wiring. Part 1 of 2.42K viewsYouTube · 7 years agoClick to view on YouTube6:24HVAC Electrical Troubleshooting -Fan Relay!35K viewsYouTube · 2 years agoClick to view on YouTube10:53Blower / Heat Relay Interlock Wiring19K viewsYouTube · 2 years agoSee more videos of furnace relay wiring Wiring diagram for furnace relay & thermostat common wire May 26, 2016because my furnace's two "T" wire connections are the same as here, but the connections are a little confusing. Is there such a thing as a "typical" wiring diagram for adding a new relay, so I can study it up close?