M4300 Fan Noise Without Temperature Peaks

Hi!

I bought M4300-52G-PoE+ for my apartment and ran into trouble. I understood switches like this one can be noisy but all my client devices at  the time are not PoE ones and CPU load never exceeds 25%. The temperatures I see are 36-43-44 Celsius. However after a couple of days the switch revvs up its fans to a very high level even if nothing is changed. There's no increase in temperature. No workload changes. Nothing changes. It just decides to go mad. Reboots don't help, even power offs don't. The firmware is the latest one. What's wrong with the switch?