If the selected function in your Philips Air Purifier does not work, read in the following lines what you can do to solve the issue.
I cannot activate the functions of my Philips Air Purifier
The air purifier is in standby mode
If your Philips Air Purifier is connected to the mains but the power button has not been pressed, the appliance will be in standby mode. When this happens, your selected function or time would not work.
To solve this, simply press the power button so your purifier will be switched on again.