Classic purifier is stuck on the high-speed level / Display light is orange or red.

Only applicable to Classic (200/400/500/600) series
To resolve this, you will need to clean the sensors on the purifier. See the steps below:

1. On the bottom or side of the machine there is a small 3-inch rectangular panel held in place by a screw, which has two circular groups of holes. The sensors are behind these holes.
2. Do Not unscrew or remove this panel.
3. Clean out the sensors by using a can of compressed air to spray 3-4 second bursts into the holes.