Performed heater tune-up on a Carrier two stage furnace system. Checked the electrical, mechanical and performance systems of the unit. Cleared, cleaned, flushed and treated the drain line and cleaned the exterior of the furnace. Secured wiring for the inducer motor to prevent any electrical rub outs. I also found the AprilAire 510 filter is starting to get dirty. No other issues were found. The system is operational at this time.