Mitsubishi Electric FR-D720-0.2K-G Instruction Manual page 237

Useful functions
(5) Cooling fan life display
The cooling fan speed of 50% or less is detected and "FN" is displayed on the operation panel and parameter unit (FR-
PU07). As an alarm display, Pr. 255 bit 2 is turned ON and also an alarm is output to the Y90 signal.
NOTE
 For replacement of each part, contact the nearest Mitsubishi Electric FA center.
Parameters referred to
Pr. 800 Control method selection
234
Refer to page 77.