Diagnosis
The continuous drain hose setup is incorrect or obstructed. The internal pump has either failed, is air-locked, or cannot overcome the height/distance of the hose run.
How to Fix It
Unplug the unit. Ensure the drain hose (3/4" ID) is pushed firmly onto the rear spigot and secured with the provided clamp. The hose must run downhill with no kinks or high loops. For the pump to work, the total lift (vertical height from pump to drain point) must not exceed 16 feet. The hose run should not exceed 100 feet.
If That Didn't Work
Prime the condensate pump. With the unit unplugged and the bucket removed, pour a cup of water directly into the drain pan outlet at the back of the unit to fill the pump housing and eliminate an air lock.
Heads Up
The unit must be perfectly level for the internal float switch in the drain pan to trigger the pump. Use a level on the top of the unit and adjust the wheels/castors.