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Automotive Air
Conditioning
It seems only a few years ago air
conditioning was a real luxury. Very few cars came with air conditioning installed from
the factory. The garage where I first worked, installed 'add on air' Now it's rare
for a new car not to have air conditioning.
Basic maintenance is about the same as the cooling system; clean leaves and bugs from the
front of the car. good air flow is very important.
It seems to be a good idea to use the air conditioner in the winter to
help defrost the windshield. (Not all cars do this automatically) Use
the air conditioner at least once per week if possible to help keep the
seals pliable.
Some loss of freon after a few years may be 'normal'
Seals wear and loose pliability after being subjected to heat and vibration. Under
hood temperatures "cook" hoses and coupling seals.
We suggest an air conditioning "check up" at the
first sign of diminished cooling.
Anatomy of an automotive air conditioner
Compressor
The 'heart' of the
system, pumps refrigerant
through the air conditioning system.
Refrigerant (freon)
is a hot gas when it leaves the
compressor
and must be cooled and allowed to
'condense'
to a liquid state.
Condenser
The hot gaseous freon goes from the
compressor to the condenser.
The condenser looks similar to,
and is mounted in front of the radiator. Air flowing through the
condenser cools the freon. The freon
gives up heat to the air and changes to the liquid state. From there
it flows to the
receiver-drier.
Receiver / drier
The liquid freon is "stored" in the
receiver-drier
for a time
until it flows to the
expansion valve.
While being stored, the
freon comes in contact with a desiccant material that removes
moisture that may be in the system.
Freon must be dry. Water
and freon molecules can combine to form acids that do
damage to the system.
Expansion valve
The
expansion valve
controls the amount of freon flowing into
the evaporator. Like a water valve, it
controls the flow of liquid.
The amount of freon allowed to enter controls the temperature
in the evaporator.
Evaporator
The
evaporator
looks somewhat like a small radiator. Liquid
freon, under high pressure, is metered into the evaporator
(which is at a much lower pressure) and allowed to change
from a liquid back to the gaseous state. The blower motor
directs the air inside the cab across the evaporator. Heat is
removed from this air when this change of state occurs, cooling
the inside of the vehicle.
Compressor
The compressor starts the 'process' over by compressing the
freon gas and sending it to the
condenser. The freon gas has removed heat from inside the vehicle. The
condenser will give up this
heat to the air.
Diagram courtesy Marshall Brian
howstuffworks.com |
