Should an air handler be running all of the time?

Whether your indoor air handler should run continuously depends entirely on how your thermostat's blower fan setting is configured. If your thermostat fan switch is set to the "On" position rather than "Auto," the air handler blower motor will run continuously twenty-four hours a day, circulating air constantly regardless of whether the heating or cooling system is actively active. While continuous fan operation helps maintain even indoor temperatures and improves air filtration through your filter, it increases electricity consumption and can cause indoor humidity to rise in summer as moisture on the coil evaporates back into the home. If your fan switch is set to "Auto," the air handler will only run during active heating and cooling cycles. You can verify your current configuration by checking the fan switch setting on your thermostat display screen.