Which AC brand lasts the longest?

Which AC brand lasts the longest? AC brand that lasts longest is debated but brands known for longevity include Trane, American Standard which is sister brand to Trane sharing same components, Carrier, Lennox, and Daikin. Trane often cited as longest lasting due to heavy duty construction, Climatuff compressors, and extensive testing, many Trane units from 1990s still operating after 20-25 years. American Standard same as Trane with different badge also long lasting. Carrier and Lennox also have long life when properly maintained, with expected life 15 to 20 years for AC, 20 to 30 years for furnace. Geothermal heat pump brands like WaterFurnace and ClimateMaster last longest overall, ground loop 50 plus years, indoor heat pump 20 to 25 years. Longevity depends more on installation quality per Manual J and D, proper sizing, correct refrigerant charge, airflow, and regular maintenance than brand alone. Premium variable speed units with proper airflow last longer than builder grade. Coastal environments reduce life due to corrosion. So brand that lasts longest typically Trane or American Standard or Carrier when installed by qualified dealer with regular service, achieving 20 plus years, but geothermal systems last longest by type.