Heater not heating. Heating repair and maintenance tune up. Diagnose and perform annual heater maintenance service plan on Ruud heating system. Replace filters and check furnace on 11 year old HVAC system. Heater maintenance complete which will help lower heating cost for this residential customer. R22 refrigerant was phased out in January 2020. Recommend replacement with new Comfortmaker air conditioning system. Heating system is now ready for winter weather.