Free Automotive Repair Advice by Certified ASE Technicians
How Does it Work /
Air Conditioner
How a Car Air Conditioner Works
Air conditioning facilitates the removal of heat from inside the vehicle. The
principle applied is that heat is removed by conduction and convention.
An evaporator which is cold, absorbs the heat from the air that is passed through
it, then cold air is forced out through the vents inside the car by the blower motor.
This is done by pressurizing refrigerant (134a) with a compressor and then releasing refrigerant
(134a) inside the air conditioner evaporator.
Car Air Conditioner System
Some automobiles are equipped with an automatic climate control system to regulate
the temperature inside the car automatically. The climate control module is a computer
which monitors and adjusts to a temperature set by the user. The temperature
is controlled by a combination of cold air from the air conditioner, and hot air
from the heater to achieve a desired temperature. The blower motor speed is controlled
by a solid state speed controller. This controller electrically controls the speed
of the blower motor and replaces the conventional blower motor resistor system.
Typical Air Conditioner System (appearance may very)
The air conditioning and heating unit provides thermal comfort to passengers inside
whatever the temperature outside. The air inside can be heated, cooled, disinfected or ventilated.
The climate control feature helps to maintain the desired temperature. The system
that provides cooling, heating and
climate control is known as the HVAC (heating, ventilation, air conditioning)
system. Basic principles of fluid mechanics, thermodynamics and heat transfer
are control the system. Your climate control settings allow all three to
work together to achieve good indoor air quality, thermal comfort and optimal pressure.
Climate Control Center
The climate control system can store trouble codes when a problem is detected
in the system. You can retrieve codes by pressing two or more buttons on the
control panel at the same time. To find out how to retrieve trouble codes for
you vehicle check your owners manual or consult a
repair manual. When the code retrieval system is enabled a trouble code
will appear on the temperature control head. After repairs have been made the
system will need to be re-enabled this is done by disconnecting the battery
for 45 seconds and reconnecting the battery. Testing can be aborted at anytime
by turning the key to the off position.
Compressor
The air conditioning compressor is the refrigerant pump of the
air conditioning system. The compressor compresses refrigerant inside the system
and circulates it to the condenser and then to the evaporator. The evaporator is
where the pressurized refrigerant is released, causing a drop in pressure resulting
in a cold evaporator, the low pressure refrigerant is then returned to the compressor
to be re-pressurized. The air conditioning compressor is driven by a drive belt
that is powered by the engine and can be engaged and disengaged by an electromagnetic
coil on the front of the compressor.
Air Conditioner Compressor
To maintain the efficiency of air conditioning system the compressor drive belt
should be checked regularly. In case it is worn out or degenerated it should be
replaced. The system's hoses should be checked for deterioration, bubbles, cracks
and hardening or oily residue, all could be signs of leakage. The correct refrigerant
charge should always be maintained, low system refrigerant charge is a common cause
of a weak AC system.
Air conditioning odors are developed when a fungus has grown on the evaporator core,
warm damp surroundings provided the perfect breeding ground for fungus which grow
with moisture. Aerosol disinfectants can be used to avoid this condition, while
the air conditioner system is running on the full high setting with recirculation
feature activated, spray a disinfectant into the inlet of the ac system (under the
dash on the passengers side) the odor can be prevented from returning by repeating
this procedure periodically throughout the summer months.
Basic Maintenance
a. Automotive charging kits are available at any auto parts store
and it is recommended to buy can with red or green refrigerant dye which can help
to point out the location of any refrigerant leaks. The kit will have instructions
to add the refrigerant safely. Protective eye wear should be used when handling
pressurized refrigerant cans.
b. Sometimes bugs, leaves and dust particles can get stuck in
the condenser fins. Foreign objects and dirt can be cleaned with the help of a garden
hose or compressed air forced through the radiator and condenser backwards until
clean.
NOTE:
a. The air conditioning system is always under pressure, until
the system is discharged completely, no repairs or disassembly should be performed.
Eye protection should always be worn when repairing or servicing the air conditioning
system.
How
Does it Work /
Air Conditioner
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Air Conditioner Questions and Answers
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