The bottle in the bottom has a pump that pressurizes the bottle. If the universal adapter is not screwed on tightly enough, air escapes from the seal. The bottle never reaches the optimum pressurization point. So the pump runs continuously. The pump sounds very much like a compressor, so most likely it is caused by the lack of the good seal. The solution is to make sure that the seal is tightened down well enough. After the bottle pressurizes in a minute or two it should stop running.