What should I do if the unit doesn't cool well?

Check several things: ensure the air filter is not blocked with dust or animal hair and clean it if needed; verify the exhaust hose is connected properly and not blocked; check that the set temperature is not too high and windows and doors are closed; make sure the room is not too large for the unit's capacity; and remove any heat sources inside the room if possible. If the unit is low on refrigerant, call a service technician to inspect and top off the refrigerant.