What should be the first action taken when the indoor blower motor runs too long and the airflow is cooler?

When the indoor blower motor runs too long and the airflow feels cooler than expected, the first step to take is to check and readjust the fan on/off differential. The fan on/off differential refers to the difference in temperature that triggers the blower motor to switch on and off. If this setting is not properly adjusted, the blower may continue to run without ample heating, leading to longer operation with cooler airflow.

Adjusting this differential ensures that the blower motor runs only when adequate heat is being produced and delivered to the space, which in turn helps to optimize the heating system's efficiency and comfort level. If the blower runs longer than necessary, it can indicate that the system is not performing correctly, and tweaking this setting can help restore normal operation.

While inspecting the heat exchanger for blockages is certainly a necessary maintenance action, it is not the immediate step to take in this specific scenario, as addressing the fan differential directly pertains to the blower’s operation timing. Similarly, testing limit control settings can be important, but it would come after ensuring the fan differential is correctly set. Increasing the thermostat setting may not address the underlying issue of the blower running too long with cooler air, making it a less effective first action. Thus, adjusting the fan on/off differential directly