What does the "G" terminal on the thermostat control?

The "G" terminal on a thermostat is responsible for controlling the blower relay coil. When the thermostat is set to either heating or cooling mode and signals for temperature regulation, it sends power to the "G" terminal. This action activates the blower motor, which circulates air through the heating or cooling system, ensuring that adequate airflow is maintained throughout the conditioned space.

Understanding this function is critical for properly servicing and troubleshooting HVAC systems since any issues with the blower's operation can directly impact the effectiveness of heating or cooling. The "G" terminal does not control the heating circuit, cooling circuit, or defrost unit, which are associated with other designated terminals on the thermostat. This distinction highlights the specific role played by the "G" terminal in the overall operation of HVAC systems.