The answer to 'why is my dehumidifier short cycling' is that your dehumidifier is turning on and off rapidly, not running for long periods. This can be caused by several common issues, including an oversized unit, dirty air filters, low airflow, or a malfunctioning thermostat or humidistat. Short cycling wastes energy and can damage the compressor over time.
To troubleshoot, first check the dehumidifier's size and capacity - it should be properly matched to the square footage of the room or space. Next, clean or replace the air filters. Ensure there is adequate airflow around the unit and that vents or registers are not blocked. If the thermostat or humidistat seems to be malfunctioning, you may need to have a professional HVAC technician inspect and repair it.