What Is G Wire

G-wire – Fan, usually green. Y-wire – Cooling, usually yellow. W-wire – Heat, usually white.

What is G wire on thermostat?

G: The G terminal controls the fan relay and is responsible for turning the blower fan on and off automatically or manually via the thermostat.

Is G wire necessary for thermostat?

If there is no hidden C-wire, you can use a G-wire instead. However, you will not be able to use your fan independently when the heating or cooling isn’t running. Also, many HVAC systems are incompatible with this solution, including: HVAC systems using electric heat.