system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible for a portable air conditioner to cool down a room when it has no hose to vent hot air outside the room?

I am a finance guy, my physics knowledge is limited to highschool physics classes. Here is the story, my house has a bonus room above our garage. This room is not linked to the central duct system in the rest of the house. It has baseboard heating for the winter and in the summer obviously gets quite warm without A/C. My girlfriend comes home from the store yesterday with a portable air conditioner to remedy the problem. I have seen these types of units before, but the ones I've seen have a hose you lead out the window that vents the hot air outside, this unit has no such hose. When on, it blows substantially cooler air than the ambient air out of the front of the unit. When I put my hand near the back of it I feel heat radiating from the unit.  

My thoughts are although the unit blows cool air, without a way to vent warm air outdoors the net temperature of the room should not change. If anything it should slightly raise the temperature of the air with the heat given off my motors and pumps (most likely a negligible amount)?

Although the cool air blowing directly on you provides some relief, would conservation of energy state that this unit is essentially useless?
gpt
Depends. Your girlfriend may have gotten you a swamp cooler rather than an air conditioner. 

A normal AC would take the heat from a room and transfer it to the outside, keeping the conservation of energy. That is why those AC's are typically at windows.

A swamp cooler would instead take the heat of that room and use it to evaporate water so that the heat is transferred into the Heat of Vaporatization of the water. It does not need a vent, but it will increase the humidity of the air.