What component is likely responsible if the indoor blower motor does not start on a call for heat?

The indoor blower motor's operation is crucial for circulating heated air throughout the space when there is a call for heat. If the indoor blower motor is not starting, it is likely due to issues with the fan relay or the corresponding contacts, which are often referred to as FR (Fan Relay) contacts. These contacts are responsible for completing the circuit that allows power to flow to the blower motor when there is a demand for heating.

When the thermostat signals the need for heat, it activates the control system. If the FR contacts fail to operate correctly, the blower motor will not receive the necessary electrical current to start, leading to a situation where the blower motor remains inactive despite the call for heat. This can result in inadequate heating and airflow in the system, affecting overall comfort.

In contrast, while the gas valve, thermostat, and hot surface igniter are critical components of the heating system, they serve different functions. For instance, the gas valve controls fuel supply for gas units, the thermostat regulates the temperature setting, and the hot surface igniter initiates the combustion process. These components do not directly affect the operation of the blower motor upon a call for heat. Therefore, if the blower motor fails to start, the FR contacts are most likely the culprit