Do all portable ac units have exhaust hoses?

No, not all portable air conditioners have exhaust hoses. Some models are designed to be used without an exhaust hose, and instead use a self-evaporating system to remove the hot air. These types of air conditioners are typically more expensive than models with exhaust hoses, but they can be more convenient to use since you don't have to worry about finding a place to vent the hot air.