problem with fan rpm on ccr 1016

Hello,
i have a ccr 1016-12g today i see fan2 speed is around 700rpm-1500rpm i have attach graph for my fan speed and system health,
is the fan healthy ?
and is it normal that working in this rpm ?
graph is for past 1 year.
thanks
Screenshot_7.png
Screenshot_6.png

it seems everything is fine because i see some times (when hardware wants switch between main and auxiliary fan) no fan working for around 30seconds and in this 30seconds cpu temperature and system temperature is static and have no change.
and i check cpu temperature for last 2 years its always on 55 no change… but i see from yesterday my system temperature decrease from 31 degree to 27 Degree so i think this is the reason that fan stop working, because cooling is fine , right? so i think fans are healthy