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Automotive AirCon Know-How & Tips
AutoAirCon prepare technical information and bulletins and send them to all our existing as well as potential
customers to inform them of the latest developments and related issues in our
industry. This page will often be updated with such news as
technical articles, latest technology and basic automotive aircon know-how and
is better? Remanufactured Compressors or Rebuilt Compressors?
Compressors are pricey and may cause you to loose the repair job.
RE-BUILDERS tend to
reuse worn internal parts, seals, O-rings and repacked clutch bearings.
bearings have a short life. Therefore
you do not know how long the compressor is going to last.
compressors cost more because they use new bearings, seals, O-rings and piston
rings. Therefore they will last almost as long as a new compressor.
Automotive Air Conditioning Training
How does your car
Just about every modern car, truck
or SUV sold these days comes with air conditioning. It's so common that
most people take it for granted. You press the button for air conditioning in
your car and cold air starts to flow out of the car's vents. It's
easy, it's simple, and it's a major convenience. Could you imagine driving to a
meeting on a hot day and your car didn't have air conditioning? By the time
you got to your meeting, you'd be a sweaty, stinky mess.
Have you ever wondered how the air conditioning in your vehicle works? If you're
like most people, you probably haven't. But we're here to educate you
painlessly. Air conditioning is the process by which air is cooled and
dehumidified. The air conditioning in your car, your home and your office all
work the same way. Even your refrigerator is, in effect, an air conditioner.
While there are many physical principles that relate to air conditioning, this
article sticks to the basics. It explains the general concepts of automotive air
conditioning, the components used and what you need to know to keep your car's
A/C system working properly.
Did you know that when you turn on the A/C in your car, you are burning extra
fuel to make yourself feel cooler? It's weird to think that by burning
something you become cooler, but it's true.
Do you remember anything from your high school physics class? Basically, air conditioning systems operate on the
principles of evaporation and condensation.
Here's a simple example of evaporation. Imagine that you're swimming around in
your backyard pool on a summer day. As soon as you get out, you
start to feel cooler. Why? The water on your body starts to evaporate and turns
into water vapour. And as it evaporates, it draws heat away from your body, and
you get goose bumps. Now let's say you have a big glass of
ice-cold Coke. You take a sip and set it down on a table. After a minute or
two, you notice that water has collected on the outside of the glass. This is
condensation. The air surrounding the glass becomes cooler when it encounters
the cold glass, and the water vapour the air is carrying condenses into water.
Both of these examples occur at normal atmospheric pressure. But higher
pressures can also change a vapour (or a gas) into a liquid. For example, if you
look at a typical butane cigarette lighter, you can see liquid inside it. But as
soon as you push down on the button, butane gas comes out. Why? The butane is
under high pressure inside the cigarette lighter. This high pressure causes the
butane to take liquid form. As soon as the butane is released and it encounters
normal atmospheric pressure, it turns back into a gas.
Ok, those are the basic ideas. But how do they apply to making your car's vents
blow cool air? The principles of evaporation and condensation are utilized in
your car's A/C system by a series of components that are connected by tubing and
hoses. There are six basic components: the compressor, condenser,
receiver-drier, thermostatic expansion valve, the evaporator and the life-blood
of the A/C system, the refrigerant.
Refrigerant is a liquid capable of vaporizing or turning into a gas at a low temperature. In the past,
R-12 refrigerant was used in cars. But this chlorofluorocarbon (CFC) is harmful
to the earth's ozone layer. Consequently, all vehicles built after 1996 use
R-134a, a more environmentally friendly refrigerant. Even although it
does not affect the ozone layer as did R-12, it still contributes to the
green-house effect. By 2017 this refrigerant will also be phased out and a even
better type of refrigerant will be in use. (Probably R-1234yf which has
similar properties to R-134a, but a very low green-house effect).
Here's how an air conditioning system and its components work.
*See detail diagram below as you follow each step...
Step One: The compressor is the power unit of the A/C system. It
is powered by a drive belt connected to the engine's crankshaft. When the
A/C system is turned on, the compressor pumps out refrigerant vapour under
high pressure and high heat to the condenser.
Step Two: The condenser is a device used to change the
high-pressure refrigerant vapour to a liquid. It is mounted ahead of the
engine's radiator, and it looks very similar to a radiator with its parallel
tubing and tiny cooling fins. If you look through the grille of a car and
see what you think is a radiator, it is most likely the condenser. As the
car moves, air flowing through the condenser removes heat from the
refrigerant, changing it to a liquid state. Most cars have an
auxiliary fan to assist with this process.
Step Three: Refrigerant moves to the receiver-drier. Some vehicles
will have an accumulator instead of a
drier. This is
the storage tank for the liquid refrigerant. It also removes moisture from
the refrigerant. Moisture in the system can freeze and then act similarly to
cholesterol in the human blood stream, causing blockage.
Step Four: As the compressor continues to pressurize the system, liquid
refrigerant under high pressure is circulated from the receiver-drier to the
thermostatic expansion valve. The valve removes pressure from the liquid
refrigerant so that it can expand and become refrigerant vapour in the
Step Five: The evaporator is very similar to the condenser. It
consists of tubes and fins and is usually mounted inside the passenger
compartment. As the cold low-pressure refrigerant is released into the
evaporator, it vaporizes and absorbs heat from the air in the passenger
compartment. As the heat is absorbed, cool air will be available for the
occupants of the vehicle. A blower fan inside the passenger compartment
helps to distribute the cooler air.
Step Six: The heat-laden, low-pressure refrigerant vapour is then drawn
into the compressor to start another refrigeration cycle.
As you can see, the process is pretty simple. Just about every vehicle's
A/C system works this way, though certain vehicles might vary by the exact
type of components they have.
The best thing about air conditioning is that all you have to do is press
a button to make it work. Air conditioning systems are pretty reliable. On a
modern and relatively new vehicle, it is rare to have problems. And if there
are problems, they are pretty much one of two things:
No cool air or
insufficient cool air. As cars age, due to vibration and temperatures in the
engine compartment, you get wear and tear and things can start going wrong. If you own an older car and its A/C system doesn't
seem to be working properly, here are some general troubleshooting tips:
No Cool Air
- Loose or broken drive belt
- Inoperative compressor or slipping or faulty compressor clutch
- Defective expansion valve
- Clogged expansion valve, receiver-drier or liquid refrigerant line
- Blown fuse
- Faulty Pressure sensor
- No Gas in system due to leaking component: any of the parts listed above
or one of the A/C lines, hoses or seals
Insufficient Cool Air
- Low refrigerant
- Loose drive belt
- Slipping compressor clutch
- Clogged condenser
- Clogged evaporator
- Slow leak in system
- Partially clogged pollen filter or expansion valve
Most A/C repairs are best left to a
qualified and approved repair shop or fitment centre. Recharging the
refrigerant, in particular, requires special equipment that most people don't
own. There are a couple things you can do, however. First, make sure to have the
system checked regularly according to your vehicle's owner's manual. Second, if
you live in a place with a cold climate, it might not make much sense to run the
A/C during the winter months, but many shop technicians recommend running your
A/C system regularly, because it contains a light mineral oil in the refrigerant
to keep the compressor properly lubricated. The general rule of thumb is 10
minutes per month. A second advantage is using your aircon to demist or defog
your windows when it is raining or very cold. This works because the air coming
out of your vents is dry air therefore absorbing the moisture from your windows,
thereby clearing them.
So those are the basics behind air conditioning. The next time you're
riding along in a car and you hit the A/C button, you can be thankful for
JOB RIGHT, THE FIRST TIME!!!
Things fitment centre's,
auto electricians, workshops or anyone who does aircon repair needs to know
from our aircon experts.
Flush and Vacuum
compressor failed for a reason. There are two main reasons why compressors fail.
Number 2 is oil starvation, where the system is not properly lubricated and thus
burns out. The number 1 reason is contamination in the system. Cleaning out this
contamination is crucial to ensuring that the new compressor is not also
contaminated. We require every system to be properly flushed and vacuumed.
We recommend flushing the system, then inspecting what comes out
through a filter for discoloration or metal flakes. Always flush and evacuate
before replacing a compressor. Always use A/C system flush solvent appropriate for the
vehicle's system. If it is not
perfectly clean after the flush and vacuum, we recommend re-flushing the system.
If it is still not perfect, then we recommend replacing the evaporator and
possibly other parts such as hoses and pipes.
newer vehicles have serpentine or parallel flow condensers that simply cannot be
cleaned and must always be replaced. The same applies to the drier / accumulator and
orifice tube / expansion valve or block valve.
is crucial to a properly functioning A/C system. It is crucial to use a high
quality oil to ensure that it will not break down over time. Remember the number
2 cause of compressor failure is oil starvation, often from the oil decomposing
over time. That decomposed oil can often be the cause of the debris in a
contaminated system. We recommend a double end capped PAG oil or better. Check
the book for the proper viscosity. Oil comes as 46, 100 or 150
viscosity. You will need the correct type for your vehicle; they are not
interchangeable and higher is not better. Each compressor is designed to work
with certain oil.
Many of our new and remanufactured compressors come pre-filled with oil. We can never guarantee that
the oil is the correct amount. Most manufacturers put just a few millilitres of
oil in for testing and shipping. We can also never guarantee the quality of that
oil, or how long the oil has been in there. Oil exposed to atmosphere can
expedite the breakdown process. Therefore, we recommend dumping all oil and
starting with a sealed bottle of premium oil. Do your own measuring to ensure
the job is done properly. Also check the specifications book; many manufactures
want half oil in the compressor and half in the drier, some want all in the
compressor. Don’t guess, follow the instructions.
R134 for R134 systems and retrofits. Pure R12 for R12 systems. No exceptions.
There are lot of Refrigerant alternatives out there. And many of them
are dangerous blends which are detrimental to your vehicle's aircon system. The
bottom line is that none of those have been tested to work with the seals and
gaskets inside our compressors. We can therefore not warranty our parts when you
use these products. Ensure that you are only using refrigerant from a sealed,
trustworthy source that are able to supply a valid verification certificate of
the contents of their refrigerant. Be careful, there are many of fraudulent
products on the market!
drier is the filter on the A/C system. Some vehicles have an accumulator and
some have a receiver drier, but either way the internals do the same thing. A
new drier is required every time you change the compressor, no exceptions.
Inside a drier is a desiccant element that pulls moisture and debris from the
system. Remember that moisture from water is very bad, it alters the viscosity
and can ruin a system.
Just like you wouldn’t change your engine oil without changing your oil filter,
the same is true on A/C systems. You want that drier cleaning your system to
ensure long lasting performance. You definitely do not want that old drier
dumping debris back into the system.
modern A/C systems use O-Rings at every connection. Half of all A/C leaks turn
out to be wrong, bad or improperly installed O-Rings. We recommend that O-rings
be changed with the compressor. We recommend that as you remove an O-ring, that
you tape it to a piece of paper and note next to it where it came from. This way
if you have a problem in that area later, you can double check that you used the
expansion device is a generic term. It can be an orifice tube, expansion valve
or expansion block. An orifice tube should always be replaced, it should never
be cleaned. An expansion valve or block is a little more difficult. They should
always be removed and inspected or replaced during a repair. A stuck expansion
device can allow too much pressure to build in a system and thus blow out the
head of the compressor.
The rule of thumb is that if you are replacing the compressor because it is
leaking or not blowing cold enough, then cleaning the expansion device may be acceptable. Any other
failure requires a new expansion device. If unsure, rather always change the
the same warranty on compressors and parts as our manufacturer / suppliers which is normally one
year. Remanufactured compressors normally also carry a one year
warranty. (Above Conditions apply). While our warranty gets into
detail, the important thing to understand about it is that it is
crucial to do the job properly. Trying to cut corners will result
in a system failure. Even if you think it is “just the clutch,” there is no
excuse for not doing the job correctly the first time.
The first thing we will ask if you have a problem is to prove all the above
were done correctly. We require this, because we know that if you do the job
properly, you will probably have no problems at all.
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