Cars & trucks air conditioning repair and installations mobile service in miami-dade county
ac evaporator coil.
What does an AC evaporator do?
The evaporator’s job is to remove heat and humidity from
inside the vehicle. Heat and humidity is transferred to the outside of the
vehicle by the ac system refrigerant; as warm moist air passes over the
aluminum fins of the cool evaporator, heat is transferred from the air to the
evaporator. The moisture contained in the air, condenses on the evaporator
surface. Dust and pollen passing through the evaporator stick to the wet
surface and then drain to the outside of the vehicle. The water can often be
seen dripping from the bottom of the vehicle on humid days when the a/c system
After the expansion valve or orifice tube ,inside
the evaporator, the pressure of the refrigerant is allowed to decrease from the
high pressure of the liquid refrigerant to
a very low pressure. This pressure change inside the evaporator causes
the refrigerant to boil, or evaporate. The latent heat of absorption
from this state change makes the evaporator cold and allows it to pick
up excess heat from the outside air or re-circulated air before it reaches
the passenger compartment.
How much does it cost to replace an evaporator coil?
The evaporator core can’t be repaired, it must
be replaced. Usually the evaporator core is not an expensive part, but because
is deeply buried underneath the dash is a very hard to reach component and time
consuming repair. In most cases the whole dashboard and center console must be
taken apart to get to the hvac box.
The cost for replacing the evaporator core will
depend on the make, model and year of the car. The price range is from about $700.00
to $2000.00 dollars.
What are the symptoms of a bad evaporator core?
Refrigerant Leakage often happens because leaves or other
organic material enter the evaporator case through the exterior air intake
vents and come in contact with the evaporator’s surface, this moisture surface
and decomposition of organic materials, can form corrosive substances which
could eventually damage the evaporator core. Moisture inside the system
interacts with the oil and refrigerant and creates corrosion inside the
evaporator core damaging it from the inside out. The
evaporator fins are also susceptible to clogging from leaves or hair from pets
and other outside road debris.
the evaporator core is leaking, the ac system performance is greatly
driver and passengers start to smell some particular odor that is often
described as the odor coming from a room that is been locked for a long
cars with dual ac units another sign is that the front unit stops blowing
cold air first while the back unit still blows some cool air.
cars with front ac unit only, the vents from one side of the car blows
colder than the other one.
cycling on and off too often.
What is evaporator core in car ?
evaporator is one of the heat exchanger in your car. It resembles the
condenser, but is much smaller and usually more difficult to access it inside
the hvac case for repairs. They are generally of the tube and fin design. The
evaporator can be thought of as a “heat sponge”. It creates, together with
other ac components in the vehicle a comfortable in cabin air temperature.Tipically,
when the body is at rest (sitting) and in surroundings of 75 F and 50% humidity
with a slight air movement, the body is close to being comfortable.
What is the function of evaporator in air conditioner ?
The evaporator works with other components in the A/C system
to maintain the pressure and temperature of the evaporator to desired levels.
These components can vary, but their main function is the same-they keep the
pressure in the evaporator low and keep the evaporator cold without allowing freezing.
Some A/C systems use a temperature sensor to prevent evaporator freeze-up by
shutting off the compressor.
What is the difference between an evaporator and a condenser ?
The evaporator core and the condenser coil both are heat
exchangers devices. The main difference between the evaporator core and the
condenser is that the evaporator core absorbs heat into the system, cooling
down the surrounding air; the condenser on the other side rejects heat created
by the compression action of the ac compressor and the heat in the area been
What state is refrigerant in the evaporator ?
Inside the evaporator core the refrigerant enters as a
mixture of about 75% liquid and 25 % vapor.The ideal temperature of the
evaporator is approximately 34 F.To maintain this temperature, low pressure
liquid refrigerant is metered into the evaporator. As this happens the
refrigerant changes state from a liquid to a vapor and cools the evaporator.
Warm air is directed over the evaporator from the hvac blower fan, and then the
heat in the air is transferred to the refrigerant in the evaporator. This heat
is then carried off with the refrigerant to the outside of the vehicle.
What is the function of the evaporator ?
The ac evaporator core is located inside the hvac box
underneath the dashboard of your car. The temperature of the coil is lower than
the in cabin air temperature being pushed thought it by the action of the
blower motor, because of this the evaporator is able to absorb the heat from
the passing air and lower its temperature and humidity.
The evaporator absorb heat from the medium being cooled.
Allow the heat to boil off the liquid refrigerant to a vapor in
its tubing bundle.
Allow the heat to superheat the refrigerant vapor in its tubing
Filters the air and get rid of road debris and other forms of
contamination from inside the car.
Dehumidify the air and adjust the humidity to level more
comfortable to the human body.
What happens to refrigerant in the evaporator ?
The refrigerant coming from the metering device enters the
evaporator coil from the bottom as a mixture of about 75% liquid and 25 %
vapor. Evaporators are usually fed from the bottom to help ensure that no
liquid leaves the top without first boiling off to a vapor. If they were fed
from the top, liquid could quickly drop by its own weight to the bottom before
it is completely boiled off to a vapor. This protects the compressor from any
About halfway up the coil, the mixture becomes more vapor
than liquid. The purpose of the evaporator is to boil all of the liquid into a
vapor just before the end of the coil. This occurs approximately 90% of the way
through the coil, leaving pure vapor.
At the point where the last droplet of liquid vaporizes, we
have what is called a saturated vapor. This is the point where the vapor would
start to condense if heat were removed from it or become superheated if any
heat were added to it.
What are the types of evaporator ?
Numerous types of evaporators are available, and each has
its purpose. The first evaporators for cooling air were of the natural
convection type. They were actually bare-pipe evaporator with refrigerant
circulating through them. The stamped evaporator was one of the first designs
to create a large pipe surface.
The evaporator’s job is to remove heat and humidity from inside the vehicle. Heat and humidity is transferred to the outside of the vehicle by the ac system refrigerant; as warm moist air passes over the aluminum fins of the cool evaporator, heat is transferred from the air to the evaporator. The moisture contained in the air, condenses on the evaporator surface. Dust and pollen passing through the evaporator stick to the wet surface and then drain to the outside of the vehicle. The water can often be seen dripping from the bottom of the vehicle on humid days when the a/c system is operating.