If you learned about heat transfer you learned there is no such thing as cold transfer, so how does air conditioning work?  There is no such thing as cold transfer but during heat transfer one object has to give up heat energy to the object with less heat.  What some people may consider cold transfer is heat extraction.  To understand air conditioning we need a solid understanding of the states of matter.  What are the states of matter?  You've probably heard of them, solids, liquids, and gasses or vapors.  There are two more states that we know of but for air conditioning solid, liquid, gas is what we need to know.  We also need to know how pressure or the lack of pressure can effect changes in state.

Air Conditioning