How does the ECO mode work, and when can I use it?

ECO mode is only available in COOL (cooling) mode. When activated and the set temperature is below 24°C (75°F), the remote controller will automatically adjust the temperature to 24°C (75°F) and set the fan speed to Auto to save energy. If the set temperature is already above 24°C (75°F), pressing ECO will only change the fan speed to Auto while leaving the temperature unchanged. (Page 12/Page 29)