Car Air condition cycle

Car Air condition cycle
Present to /
Pro. Dr. Saad Abd El hamid
‫‪Car Air condition cycle‬‬
‫‪Present from :‬‬
‫‪ -1‬رنـــــــا السيد العربي غريب‬
‫‪ -2‬سمر حامد أبو الفتوح صيـــــام‬
‫‪ -3‬خـــلود علي علي المرسى‬
‫‪ -4‬نسمة محمد حافظ عبد هللا المقدم‬
‫‪ -5‬مروة متولي عبد المطلب الشيخ‬
Components of cycle
4-thermal expansion valve
Commonly referred to as the heart of the 
system, the compressor is a belt driven
pump that is fastened to the engine. It is
responsible for compressing and
transferring refrigerant gas.
The A/C system is split into two sides, a 
high pressure side and a low pressure side;
defined as discharge and suction. Since the
compressor is basically a pump,
it must have an intake side and a discharge
side. The intake, or suction side, draws in
refrigerant gas from the outlet of the
evaporator. In some cases it does this via the
Once the refrigerant is drawn into the suction
side, it is compressed and sent to the
condenser, where it can then transfer the heat
that is absorbed from the inside of the
This is the area in which heat dissipation 
occurs. The condenser, in many cases, will
have much the same appearance as the
radiator in you car as the two have very
similar functions. The condenser is designed
to radiate heat. Its location is usually in front
of the radiator, but in some cases , due to
aerodynamic improvements to the body of a
its location may differ. Condensers must have 
good air flow anytime the system is in
operation. On rear wheel drive vehicles, this is
usually accomplished by taking advantage
of your existing engine's cooling fan. On front 
wheel drive vehicles, condenser air flow is
supplemented with one or more electric cooling
As hot compressed gasses are introduced into 
the top of the condenser, they are cooled off. As
the gas cools, it condenses and exits the
bottom of the condenser as a high pressure
Located inside the vehicle, the evaporator 
serves as the heat absorption component.
The evaporator provides several functions.
Its primary duty is to remove heat from the
inside of your vehicle. A secondary benefit is
dehumidification. As warmer air travels
the aluminum fins of the cooler evaporator coil, 
the moisture contained in the air condenses on
its surface. Dust and pollen passing through
stick to its wet surfaces and drain off to the
outside. On humid days you may have seen
this as water dripping from the bottom of your
vehicle. Rest assured this is perfectly normal.
Thermal expansion valve
thermal expansion valve
Another common refrigerant regulator is the 
thermal expansion valve, or TXV. Commonly
used on import and aftermarket systems.
This type of valve can sense both
temperature and pressure, and is very
efficient at regulating refrigerant flow to the
The receiver-drier is used on the high side 
of systems that use a thermal expansion
valve. This type of metering valve requires
liquid refrigerant. To ensure that the valve
gets liquid refrigerant, a receiver is used.
The primary function of the receiver-drier is
separate gas and liquid. The secondary 
purpose is to remove moisture and filter out dirt.
The receiver-drier usually has a sight glass in
the top.
A thermostat is a device for regulating the 
temperature of a system so that the
system's temperature is maintained near a
desired set point temperature.
Air conditioning facilitates the removal of heat 
from inside the vehicle. The principle applied is
that heat is removed by conduction and
convection. An evaporator which is cold
absorbs the heat from the air that is passed
through it and 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
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.
The air conditioning and heating unit provides 
thermal comfort to passengers inside no matter
what the temperature is 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
provide cold and heat for the particular system.
Your climate control settings allow all three to
work together to achieve good indoor air quality,
thermal comfort and optimal pressure.
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 owner's
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.