Simple basic about Automotive A/C - Part 4

Well here comes part 4 of the basic a/c understanding. Here i gonna talk about Expansion valve, Evaporator, and Ventilating Blower (which can also called as Blower in short).


Currently there is 2 kind of Expansion valve that can be found in car a/c, both work in same principle.

Before refrigerant go into the evaporator, it will travel through filter drier, then arrive at expansion valve. In this stage, the refrigerant is in its liquid state, and it will feel warm to touch and is very high in pressure. Here is where the magic happen. The expansion valve will convert this high pressure liquid refrigerant into low pressure refrigerant. The lost in pressure of refrigerant will convert the refrigerant from warm to cold immediately.


Evaporator comes in different pipe arrangement and shape. The left is Serpentine type, while right is Parallel type.

This cold low pressure refrigerant will then enter into Evaporator and it rapidly cool down the evaporator which make the evaporator colder than the surrounding air. The Blower will then blow the hot and humid surrounding air through the evaporator where the hot air will be convert into cold dry air and leave the evaporator. This cold air is what we feel at the ventilating in our car.


Picture at left is how the Evaporator work, and right is what Blower looks like.

The low pressure cold liquid refrigerant will be convert into its gases state while travel inside the evaporator. This low pressure gases refrigerant will be suck back into compressor and the whole process begin again in continuous loop.

So this is all the basic we need to know about automotive air condition. I may have rush to explain this in simple, because many parts cannot be explain in this 4 parts of posts. I will post each of the parts related in their dedicated post. In there i will further explain in detail.

Stay tune for more understanding of our car a/c system.