The answer to 'when to service air handler' is that you should service your air handler unit at least once a year, or more frequently if recommended by the manufacturer. Regular maintenance helps ensure your HVAC system is running efficiently and can extend the lifespan of your equipment.
During a service visit, an HVAC technician will typically inspect the air handler, clean the components, check for any issues, and make necessary adjustments or repairs. This includes checking the air filter, cleaning the blower, and testing the electrical connections and controls.