There are several reasons this may be happening. The 2 primary reasons are the humidity extraction level is set to high. Lower it to 35% . The lower the setting, the more moisture/humidity is extracted from the air. The higher the setting, the less if any moisture. humidity will be extracted from the air.
On most humidifiers the fan runs almost constantly while in operation. The idea is to continually move the air around and when the unit senses a rise in humidity, above what you have it set on, the compressor will turn ON to extract that humidity.

The 2nd thing that causes the problem is a dirty of clogged intake air filter. Which is easily solved by removing and cleaning the filter. Which should be done at least every 2 weeks, while the dehumidifier is in operation.

I said there were 2 reasons. Actually, there is a 3rd. Not enough clear air space all around the dehumidifier. A minimum of 12" should be maintained during operation.

Hope this helped you to troubleshoot and solve the problem. Please let me know. Thanks.