That's interesting. It's really undoubtfully noisy to be a non PoE/PoE+ 48 Gigabit Ethernet fixed ports Switch.
Never checked if just a display fan CLI command ever exists on those models.
A thing one can note is that the non-PoE+ model HPE OfficeConnect 1920 48G Switch (J927A)'s QuickSpecs reports a just one fixed acoustic pressure level (49,7 dB) instead the PoE+ model HPE OfficeConnect 1920 48G PoE+ Switch (J928A)'s QuickSpecs reports two acoustic pressure levels (Low speed fan: 47 dB, High speed fan: 49,3 dB)...and the general Overiew reports this statement: "...utilizes variable-speed fans..." (read it under Green IT and Power paragraph).
Another interesting thing is that, AFAIK, no HPE OfficeConnect 1920 owns a temperature sensor (and so reported temperature on web UI - even if it is 0°C - is just a cosmetic bug)...so, eventually, if fan speed is really variable (on PoE+ models), it is so automatically and in relationship with something (maybe CPU Load? amount of PoE ports really supplying power to devices? etc.) that isn't directly related to Switch internal or Ambient temperatures.