ACs, furnaces, and heat pumps have different functions and thermostat wiring configurations. Furnaces are the simplest system, providing simple heat that's usually just turned on and off.. Below is a guide to the most common configurations with a wiring diagram for each, but I recommend following the manufacturer's instructions to get the.. Step 5: Wire the Furnace. Connect the wires from the thermostat to the furnace according to the wiring diagram: Connect the white wire from the W terminal on the thermostat to its W terminal. Connect the red wire from the Rc terminal on the thermostat to its R terminal. Connect the yellow wire from the Y terminal on the thermostat to its Y/Y2.
Starting on the upper right side of the diagram above: RC - Red: This wire provides 24 volt power from the furnace to the thermostat so that the thermostat can control air conditioning. R - Red: This wire serves the same purpose as the RC wire but for heating. Y - Yellow: Cooling Mode. This wire runs to the furnace control board which in turn controls the activation of the compressor and.. Gas furnace wiring diagrams typically include components such as the thermostat, gas valve, transformer, fan motor, and control board. Each component plays a crucial role in the proper functioning of the furnace, and understanding their interconnections is key to troubleshooting and repair.