Diagnosis
The UV-C bulb has a safety interlock. It will only activate when the unit is powered on, the front grill is correctly latched shut, and the bulb itself is properly seated in its socket. A new unit often has the bulb loose in shipping.
How to Fix It
Unplug the purifier. Open the front grill. Locate the clear plastic UV-C bulb housing near the top inside. Firmly press the bulb into its socket until it is fully seated. Close and securely latch the front grill. Plug the unit back in and turn it on. The UV-C light should glow blue.
If That Didn't Work
The bulb may be defective. The AC5350B uses a specific 10-watt UV-C bulb (part number AP50T10H). You can order a replacement. Ensure you are checking in a dimly lit room, as the blue glow can be subtle.
Heads Up
Never look directly at the UV-C light when it is on. The bulb has a limited lifespan (typically 6-12 months of continuous use) and will eventually need replacement even if the purifier fan still works.