Troubleshooting My Philips Dehumidifier does not work while switched on If your Philips Dehumidifier will not work even though it is switched on (it does not collect water), there might be a simple solution. Discover here how to solve it yourself. The humidity is too low Your Philips Dehumidifier is equipped with a sensor. Once the humidity level has reached the desired low level, your dehumidifier will stop collecting water until it detects higher levels again. The water tank is full When the water tank is full, your Philips Dehumidifier will go into purification mode only and will stop dehumidifying. To solve this, please empty the water tank. Defrosting mode is activated When your dehumidifier is in defrosting mode, it will not dehumidify. The defrosting indicator (see image below) will tell you it is in defrosting mode. Your Philips Dehumidifier is designed to enter into defrosting mode when low temperature is detected. It will resume dehumidifying once it has finished defrosting.