Diagnosis
A corrupted or blank display with the fan still operational indicates a failure of the LCD control panel or its connection to the main logic board. A power surge or internal moisture can cause this.
How to Fix It
Perform a full power cycle reset. Unplug the unit from the wall outlet. Wait 5 minutes. While unplugged, press and hold the power button on the unit for 30 seconds to discharge any residual current. Plug the unit directly into a wall outlet. Press power. Check if the display normalizes.
If That Didn't Work
The display module is defective. The AC5350B uses a specific integrated display and control panel. You can operate the unit blindly if you remember the button sequence (power, then fan to cycle speeds), but you will lose filter reset and mode functions. Replacement of the display assembly is required.
Heads Up
Operating with a failed display means you cannot see the filter timer, set Auto mode, or use the UV-C light toggle. The UV-C light will default to ON if it was on before the failure, which will shorten its bulb life.