automotive AC course
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 used in an automotive AC system
The compressor causes the refrigerant to flow through the tubes
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 it's called condenser
As 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 several times ON and OFF
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, 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
Both are dryers, but have different functions
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
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 put after the condenser and has the function
of storing liquid
so that the refrigerant can arrive as the expansion valve as a liquid and not vapor
The accumulator type is after the evaporator and has the function of accumulate
liquid but,
release only vapor, to 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
When a vehicle has a liquid receiver or accumulator is
linked to the fact of the vehicle have
expansion valve or orifice tube
We will study this filters and the way they work in the system during this course
See you in the next lesson
