So cooling coils is not an accurate word to use in small air cond units. Evaporator coils should be used instead. Evaporator tubes must contain refrigerant liquid that can evaporate to become gas.

In an air conditioning system, when liquid refrigerant absorbs heat, it turns to gas. The heat is thus transfered to refrigerant. That's how heat is moved from one location to another location.

The evaporator coils are located in low-pressure system of a refrigeration circuit.

The refrigerant has property of changing its state from liquid to vapor at normal room temperatures.

Have you ever felt your skin becoming cool whenever you put alcohol on it? Or even when a bit of petrol spilled onto your hands? It's because, alcohol or petrol has evaporated when it comes in contact with your skin.

The result - heat is removed from your skin, and it feels cool!

In a closed-loop refrigeration circuit, change of state from liquid to vapor is achieved mechanically by pressurizing liquid at one end and forcing it through a small opening at another end.