> Also, old air conditioners regularly lasted 30+ years, so this is a solved problem, and the patents have probably expired. Survivorship bias argument. Also,

> Also, old air conditioners regularly lasted 30+ years, so this is a solved problem, and the patents have probably expired. Survivorship bias argument. Also, EPA has much stringent standard, my 50 years old AC using probably has a shitty 6 SEER (compared to 22 SEER for the best units these days), refrigerant has changed too, manufacturing tolerances are much tighter now, higher demand and lower prices has probably caused material quality to plummet as well...