I have a dehumidifier, about 4 years old, that doesn't dehumidify. it runs, appears to try to engage the condenser, then returns to fan immediately. the setting is appropriate from past experience, with humidity in the 50% range.
Can you hear the compressor come on or just clicking?
The compressor comes on, or seems to, for a second or two, then back to the fan.
If the compressor is coming on and going off, I would replace the humidistat. If the compressor does not come on then I would think you have a bad compressor and it might be under warranty, you would have to check in owners manual.
Experience: Ten Years experience. Certified in most major brands Including Whirlpool Frigidaire maytag Amana.