What is the FP function and how do I activate it?

The FP function can only be activated during heating operation (when the setting mode is HEAT), and causes the unit to operate at a setting temperature of 8°C. To activate it, press and hold the SILENCE/FP button for more than 2 seconds; press and hold it again for more than 2 seconds to disable it. The display window of the indoor unit will show 'FP', and pressing ON/OFF, SLEEP, FP, MODE, FAN SPEED, UP, or DOWN will cancel the function. (Page 3)