The article reviews how home air conditioners work in hot weather (40 °C and above). Researchers looked at different ways to make them better, like using new coolants and improving parts like the condenser and compressor. Upgrades to the condenser improved cooling by up to 30% and efficiency by up to 50%. Fewer studies focused on the evaporator, but those that did found a 7% efficiency boost. Upgrading compressors led to lower temperatures and higher cooling power. New coolants showed promise, with some matching old ones for efficiency and cooling power. However, none beat one popular old coolant. In comparing options to replace this old coolant, the new ones mostly showed lower efficiency except for some that were on par or slightly better.