Main parts of an automotive AC system

This lesson will show you the more important parts of an automotive air conditioning system.
In future lessons we will detail these parts and also show other auxiliary components and their failures.

By the end of this course you will learn how to diagnose failures using a manometer, vacuum the system
and also charge the refrigerant with or without a scale.

Compressor

The compressor is the heart of an air conditioning system.

Below you can see a compressor which is used in an automotive AC system.


The compressor causes the refrigerant to flow through the tubes and then the refrigerant flows through the condenser, evaporator and other parts of the system.

It works almost like a home refrigerator compressor. The difference is that the automotive AC compressor does not use electricity to work. It has a pulley that is moved by the vehicle engine.

Condenser

Because the refrigerant leaves the compressor in high pressure, it's hot and vapor.

As it flows through the condenser, it loses part of its heat, condenses and becomes a liquid.

For this reason this part is called condenser.


Because the vapor is too hot, the condenser itself is not enough to dissipate the heat on the air.

For this reason a fan is used to vent the heat from the condenser to the air outside.



The fan circles ON and OFF several times.

Some vehicles have two fans; one for the condenser and other for the radiator engine.

Below we can see a double fun sample.



Caution: A vehicle fan can spin suddenly even if the vehicle is OFF. Keep your hands far from fans and belts.

Expansion valve

Inside the expansion valve, the fluid expands and lose pressure.



As the fluid expands, it becomes cold and is ready to go to the evaporator.

Expansion Orifice tube

The orifice tube has the same function of the expansion valve, and vehicles with orifice tube do not use the expansion valve.

Below you can see some orifice tube samples.



Though expansion valve and orifice tube have the same function but there are some differences in the way they work.

Those differences will reflect the way system is assembled.

One of the differences is that in vehicles using expansion valve there is a dryer liquid receiver after the condenser.
The orifice tube systems uses an accumulator drier after the evaporator.

After flowing through the expansion valve or orifice tube, the refrigerant goes to the evaporator.

Evaporator

Because the fluid is cold, when it passes through the evaporator, its surface becomes cold.




The outside air is blew against the evaporator surface which is cold.

So the air becomes cool and is blew into the cabin.

The user turns the blower ON by a button in the car panel.

As a matter of fact, the cold is not generated, but the heat is removed from the cabin instead.

Below we can see some blowers.


As the fluid flows inside the evaporator, it absorbs the heat inside the cabin and its temperature increases.

So, the fluid leaves the evaporator in vapor state.

Dryer filters

The dryer filter has an important role in refrigeration systems because it keeps the system free of moisture and particles.

The dryer filter is in series with the system so that the refrigerant passes through it.

However we must observe that there are two types of filter.
The first one is a liquid receiver and the right one is a accumulator.



The liquid receiver dryer type is placed after the condenser and has the function of storing liquid so that the refrigerant can arrive in the expansion valve as a liquid and not vapor.

The accumulator type is after the evaporator and has the function of accumulate liquid and release only vapor, so that the refrigerant can arrive in the compressor in vapor form and not liquid.

Both filters have dryer and filter function but works just the opposite in their refrigerant storage function.

We will study this filters more about this filters, other parts, and the way they work in the system during this course.

See you next lesson.

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