Performed biannual system, maintenance and cooling evaluation on 16 year-old American standard furnace. Blew out water removal system with CO2 and chemically treated water removal system and heat transfer media coil pan with pan. Treatment spray tested system and cooling and got a 18.5° split checked pressures and cleaned out outdoor electrical panel and disconnect electrical panel. sprayed insecticide over electrical terminals in electrical panel. Washed off outside unit with water. Reminded customer of systems age and recommended to have our comfort specialist come out and quote him on a new heat pump system. Customer no longer wants a gas furnace. System operating at manufacturer specifications at this time.