Performed Furnace precision tune up; clean and tune up furnace; clean burners, test ignition components, adjust gas level, test safety circuit, check indoor motors, checked all electrical components, tested indoor air flow, checked heating temperatures, and tested overall furnace operation. Replaced furnace filter per sunshine club membership. Also performed Air Exchanger cleaning and tune up. Remove filters and core to vacuum. Also clean cabinet interior. Inspect bearings on blower assembly. Install core and filters. Clean off outside hoods. Test operation of air exchanger. Flame safety in furnace is testing below manufacture specifications. This will cause furnace to not operate if fails. Recommend replacement of part. Repair was declined today. Furnace is operating normal at this time.