DIAGNOSIS The hose isn't fully locked onto the unit's vent port. A poor seal here drastically reduces cooling efficiency by allowing hot exhaust air to recirculate back into the room.
FIX Secure the hose connection properly.
- Detach the hose completely from the unit's port.
- Inspect the plastic locking collar on the hose end and the grooves on the unit's port. Make sure they are clean and not broken.
- Align the tabs on the hose end with the slots on the port. Push the hose on firmly until you hear/feel a distinct CLICK.
- Manually twist the locking collar on the hose clockwise until it stops to lock it in place. It should not wobble.
IF THAT DIDN'T WORK The rubber gasket/seal inside the hose connector or on the unit's port may be missing or damaged. Check for it. A temporary fix is to wrap the unit's port with HVAC foil tape before attaching the hose to create a tighter seal.
HEADS UP Always use BOTH hoses. The thin hose is for intake, the wide hose is for exhaust. Connecting them backwards or using only one forces the unit to pull cool room air and expel it, killing efficiency and heating the hose.