The blue light on top has turned off. Is my unit still working?Updated a month ago

Yes, your unit is working as intended. The Core 750 is designed to have intentional downtime. The UV light turns off for 20 minutes every 2 hours to allow the reactor cell's crystalline matrix to regenerate and extend the life of the lamps. This downtime is a normal part of the purifier's operation and does not affect its efficacy, as the space is still being purified by ions during this time.