Description:
Not only do we depend on our cars to get us where we want to go, we also depend on them to get us there without
discomfort. We expect the heater to keep us warm when it's cold outside, and the air conditioning system to keep us
cool when it's hot.
We get heat from the heater core, sort of a secondary radiator, which is part of the car's cooling system. We get
air conditioning from the car's elaborate air conditioning system.
Despite its relatively small size, the cooling system has to deal with an enormous amount of heat to protect the
engine from friction and the heat of combustion. The cooling system has to remove about 6,000 BTU of heat per minute.
This is a lot more heat than we need to heat a large home in cold weather. It's good to know that some of this heat
can be put to the useful purpose of keeping us warm.
Air conditioning makes driving much more comfortable in hot weather. Your car's air conditioner cleans and
dehumidifies (removes excess moisture), the outside air entering your car. It also has the task of keeping
the air at the temperature you select. These are all big jobs. How do our cars keep our "riding environment"
the way we like it?
Most people think the air conditioning system's job is to add "cold" air to the interior of the car. Actually,
there is no such thing as "cold," just an absence of heat, or less heat than our bodies are comfortable with. The
job of the air conditioning system is really to "remove" the heat that makes us uncomfortable, and return the air
to the car's interior in a "un-heated" condition. Air conditioning, or cooling, is really a process of removing heat
from an object (like air).
A compressor circulates a liquid refrigerant called Refrigerant-12 (we tend to call it "Freon," a trade name, the
way we call copy machines "Xerox" machines). The compressor moves the Refrigerant-12 from an evaporator, through a
condenser and expansion valve, right back to the evaporator. The evaporator is right in front of a fan that pulls the
hot, humid air out of the car's interior. The refrigerant makes the hot air's moisture condense into drops of water,
removing the heat from the air. Once the water is removed, the "cool" air is sent back into the car's interior.
Aaaaaah! Much better.
Sometimes we worry when we catch our car making a water puddle on the ground, but are relieved to discover that it's
only water dripping from the air conditioning system's condenser (no color, no smell, and it dries!).
Note: Refrigerant-12 is extremely dangerous. Many special precautions must be taken when it is present.
It can freeze whatever it contacts (including your eyes), it is heavier than air and can suffocate you, and it produces
a poisonous gas when it comes in contact with an open flame.
Dash Controls
Most or all of the control panel of your car is located on the dashboard behind the steering wheel. Sometimes it
extends onto the car's
console, between the two front seats, and onto your steering column. Little duplicate fragments
of the control panel are scattered around the interior of your vehicle, such as automatic door locks, extra light
switches, etc.
The dash controls enable you to operate your headlights, turn signals, horn, windshield wipers, heater, defroster,
air conditioning, radio, etc. All of the vehicle's controls should be within the reach of the driver.
The control panel also contains all of your gauges; gas, temperature, tachometer, etc. These enable you to monitor
the operating conditions of your engine and charging system, fuel level, oil pressure and coolant temperature.
Warning lights come on to alert you to dangerous coolant temperatures, or loss of oil pressure.
In 1924 the Nash Co. introduced the electric clock as an accessory.
Relays
A relay is an electromagnetic device in which contacts are made and
subsequently broken. An example of this would
be your car's horn.
By natural law, the farther electrical current travels, the lower its voltage becomes. Your car horn has to be
connected to the car battery in
order to sound. The shortest distance between two points is a wire
connecting your
horn to your battery. The only problem with this arrangement is that connecting the two would give you a permanent horn
blast when you turned the key in your ignition.
This is an unacceptable arrangement, so a relay is included in the connection. The relay stops the horn from sounding
until you activate the relay by pressing the horn. The relay then allows the horn to connect to the battery, or complete
the circuit, and it sounds. As soon as you stop pressing the horn, the relay breaks the connection, or circuit, and presto--
no more horn!
Relays, with switches, are used for most of the equipment that depends on the battery for an energy source. This includes
headlights, taillights, radio, etc.
In 1922, a Model T was the first car equipped with a radio. In 1927, the first commercially produced car radio came on
the scene. A "relay" is any switching device operated by a low current circuit that controls opening and closing of another
circuit of high current capacity. The purpose of the "cutout relay" is to prevent the battery from discharging through the
generator when the engine is stopped or turning over slowly. A "field relay" connects the alternator field windings and
voltage regulator windings directly to the battery.
The Compressor
The compressor used to air condition your car works in a similar way to
the one in the refrigerator in your kitchen.
The job of the compressor is to move liquid refrigerant around in a pipe. The compressor pumps, or forces, the liquid from
the evaporator into a condenser and expansion valve, and then back to the evaporator.
There are three common types of compressors:
Two cylinder reciprocating piston type
Four cylinder RADIAL type
Six cylinder AXIAL type
The engine drives the compressor with a belt. In action, the compressor takes the low pressure refrigerant
from the
evaporator and compresses it according to speed and air temperature. The inlet side is known as the low (pressure) side and
the outlet side is known as the high (pressure) side.
The compressor compresses the refrigerant, and raises its temperature higher than that of the surrounding air. Then, the
compressor forces the refrigerant into the condenser.
The Condenser
The condenser is a long tube that goes back and forth through a
multitude of cooling fins, quite similar to the evaporator
in structure. The condenser is mounted in front of the radiator to take advantage of the forced air provided by the fan and
the motion of the car.
As the highly pressurized refrigerant (vapor) flows into the condenser, it gives off heat and warms the condenser. This
causes the condenser to be
hotter than the forced air coming through the condenser. The condenser
hands its heat off to the
forced air and turns the refrigerant back into cool liquid in the expansion valve, where it heads back to the evaporator.
The Evaporator
The evaporator is a long tube, or coil, that goes back and forth through a multitude of cooling fins. It is quite similar
to the condenser in structure.
The refrigerant is a liquid when it enters the evaporator. A fan blows warm air over the evaporator. The warm air causes
the liquid refrigerant
to boil. This means that it absorbs the heat from the warm air. Once it has absorbed the heat from the
warm air, the warm air isn't warm anymore. The same blower that blows the warm air (that is now "cool" air) over the evaporator,
keeps on blowing it into the interior of your car, and you
have -- air conditioning!
The evaporator also removes the moisture from the air coming through its fins and turns it into water. The water just drains
off.
The temperature of the evaporator coil can go from 33 degrees F to 0 degrees F. If it goes below 32 degrees F, the moisture
that's supposed to drain off the coils will freeze. This makes for a very (surprise!) inefficient system, so a thermostatic
switch is used to connect and disconnect it to the compressor as necessary.
Expansion Valve
The expansion valve determines the correct amount of refrigerant going into the evaporator, and it lowers the pressure of the
refrigerant.
When the compressor starts, the expansion valve opens and the liquid refrigerant flows through a strainer in the high pressure
liquid inlet. Once in the expansion valve, the refrigerant is correctly pressurized. As the evaporator calls for more refrigerant,
the expansion valve allows the required amount of low pressure liquid refrigerant into the coils.
The expansion valve maintains the delicate balance between the heat
load and the cooling efficiency of the evaporator.
Discharge/Suction Service Valves
Discharge and suction service valves allow the air conditioning system to be emptied and filled. These valves also provide
places where the system can be checked with pressure gauges.
Note: Some systems use a Schrader valve in place of the discharge and suction valves. This is a spring-loaded valve which
looks rather like the valve in a tire.
The Compressor Relay
A capillary tube from a cycling switch lets the switch know what the temperature is in the evaporator. This switch turns the
compressor on and off to keep the evaporator temperature at about 32 to 45 degrees F. The relay switch keeps moisture from
freezing on the evaporator core.
Electric Air Conditioning Fan
Sometimes an extra electric fan is placed in front of the condenser to provide an extra flow of air during warm weather, or
for times when the
car has to idle for a long time. You activate and deactivate the air conditioning fan when you turn it on
and off at the control panel.
Compressor Belt
The compressor is engine driven by a belt on the front of the crankshaft.
Heater/AC Blower Motor
The blower motor is the motor that turns the electric fan in an air conditioning or heating system.
Air Ducts
The air ducts control the passage of hot or cold air into the interior of the car. They are operated by a control on the
dash, either manually or automatically.
Controls
Most air conditioning/heating systems have three possible air settings. One is to recirculate the air that is in the car,
a second is to use only air from the outside of the car, and a third is to mix some of the outside air with the air recirculating
inside the car.
Compressor Clutch
The air conditioning compressor has an electromagnetic clutch that can engage or disengage the compressor pulley. The compressor
pulley always turns when the engine is running, but the compressor only runs when the pulley is engaged to the compressor driving
shaft.
When this system is activated, current runs through the electromagnetic coil. The current attracts it to the armature plate. The
strong magnetic pull draws the armature plate against the side of the turning pulley. This locks the pulley and the armature plate
together; the armature plate drives the compressor.
When the system is deactivated, and current stops running through the electromagnetic coil, flat springs pull the armature plate
away from the pulley.
The magnetic coil does not turn since its magnetism is transmitted through the pulley to the armature. The armature plate and
hub assembly are fastened to the compressor drive shaft. When it's not driving the compressor, the clutch pulley turns on a double
row of ball bearings.
Low Pressure Line
The low pressure line is a hose, or tube containing refrigerant that connects the evaporator to the air conditioning system's
compressor. The compressor draws the low pressure refrigerant from the evaporator in through the low pressure line in order to
compress it.
High Pressure Line
The high pressure line is a hose, or tube containing refrigerant that connects the air conditioning system's compressor to the
condenser. The compressor forces the compressed refrigerant into the condenser through the high pressure line.
AC Compressor Drive Ring
Inside the air conditioner's refrigerant compressor is a drive ring made of a friction material that is mounted to both sides
of the "swash" or "wobble" plate. As the swash plate rotates, the friction material pushes the ball bearings (mounted to the pistons)
back and forth.
The Car and the Environment (Overview)
Most of us know that cars are the number one cause of air pollution, but most of us never do anything about it until someone
makes us. This usually happens because of a law. We buy gas that causes less harmful emissions, because that's what's for sale
now. Scientists tell us that if we don't do something soon, we will be unable to repair the damage that we are causing to our planet.
What are some of the things we can do to help? 1. Buy a fuel-efficient car and keep it that way Good gas mileage isn't just a way to
save money. It's also a way to stop pollution. Since the world just isn't set up for you to start riding a bike everywhere, you're
probably going to be using a car. Choose a car that is friendly to the environment when you purchase one. Use the most recent EPA
gas Mileage Guide to check fuel-efficiency, and don't get any optional equipment that wastes fuel that you don't need. 2. Keep your
car tuned up A car that is badly tuned releases more pollutants into the air. If you keep track of your gas mileage, you'll know when
something is wrong and can have it fixed. A badly tuned car uses almost 10% more gas than a well-tuned car. Other ways to waste gas
are: Idling your car unnecessarily: If you are stopped for longer than a minute, it is more fuel efficient to turn off your engine.
Using dirty fuel filters. Dirty fuel filters waste gas. Carrying unnecessary weight in your car. The heavier your car is, the more
gas it uses.
Air Conditioner Maintenance
In November of 1990, the Clean Air Act was signed into Federal law. This law requires a complete phase out of
chlorofluorocarbons (commonly known as CFCs) and other ozone-depleting chemicals (ODCs) by the year 2000, although it might be
revised to 1997 or sooner. What does this have to do with your air conditioner?
Your air conditioner uses a CFC based refrigerant, known as R-12, or freon. This law means that there won't be much R-12 left
by the year 2000, and what is left will be very expensive, because of a tax that will reach about $5.00 per pound.
Why are they doing this to us? We like our cars to have air conditioning. This is being done because of the terrible damage CFC
based
refrigerant is doing to the ozone layer. In the U.S., the largest single source of ozone damaging emissions is from our
automobile air conditioners. It's been estimated that car air conditioners used over 48,000 metric tons of R-12 in 1989 --
this is 21% of all CFC use in the U.S.
Of course, this causes a big problem for both us and our mechanics. We won't be able to go out and buy a can to "top-off" our
systems. The new laws specify that all refrigerant will have to be recaptured and recycled when we have repairs made. Of course,
this will take expensive and
specialized equipment. Our mechanics will have to make sure that there are
no leaks, and fix them
if there are, before they can add any R-12 to our air conditioning systems. Naturally, this cost will be passed along to us.
Recovered refrigerant will be recycled. Capturing refrigerants and restoring them for reuse is not only environmentally sound,
but mechanically safe. Each molecule of CFC in the atmosphere has a 120 year life that will destroy tens of thousands of ozone
molecules. This means that a CFC molecule released in 1991 will still be damaging the ozone layer in 2100.
Gas Ecology
There are many ways that we can reduce pollution by observing good gas ecology -- that is using our cars in fuel efficient ways.
Don't move the car unless you are going somewhere. Plan ahead. Starting
the car up just to move it a short distance produces
more pollutants than hours of driving on the freeway.
Don't use your heater until the car is warmed up. The engine will warm more quickly, because it won't be losing heat to warm you.
Try to drive within 35-45 miles per hour when possible. Driving at slower speeds reduces engine efficiency and causes more
pollutants.
Don't make fast starts or stops. Fast starts can burn more than 50% more gas than regular acceleration (as well as cause 50%
more emissions). When a big burst of gas enters the engine, much of the catalytic converter's job is bypassed and the unburned gas
comes out the tailpipe or is sent into the converter. Rapid acceleration is only called for in
emergency or passing situations.
Stopping rapidly also leaves the engine with a lot of unburned gas to deal with. This results in damage to the converter and pollution.
Try not to idle. At bank lines and fast food places with over thirty second waits, turn the engine off, and restart it. It is
more fuel
efficient, and causes less pollution. The only time that idling is a good thing is after a long, fast run. Idling the
engine for a minute or so after one of these helps get rid of any hot spots and fuel vapors.
Keep to steady speeds on the highway. Changing speeds produces more
pollution and uses more gas.
Don't use the air conditioner unless you have to. It makes your engine work harder, uses more gas, and causes more pollution.
Most evaporative emissions get into the atmosphere when we put gas in our cars. Make sure your gas cap is the right one, and in
good working order. Gas caps don't cost that much, but are very important in anti-pollution.
Since gasoline expands, never overfill your tank. It will wind up leaking out.
Use known brands of gas. Poor quality gas will not save you money. Instead, it will foul your engine and cause it to function
badly. Try several different brands and octane ratings to find out which makes you car the happiest, and stay with it.
Fuel Conservation
In addition to the ways mentioned to be "gas-ecological," there are
other ways that you can conserve fuel.
Don't drive around the parking lot for hours waiting for a convenient space to "open up." Americans do this all of the time.
Just think of the gas that we could save (not to mention pollution) if we all just parked in the first spot we could find, and
walked! It would probably save time, too (the reason we're so intent on finding a "close" parking spot in the first place).
Use carpools, vanpools and public transportation. Although this means that you'll have to give up some of your "freedom," it
doesn't necessarily mean that in the long run. If you don't do it now, by your own freedom of choice (the pollution situation
won't go away on its own) soon regulations may order you to give up your freedom. If this happens, it won't be on
your schedule.
It will be on the law's schedule. They might order you not to drive on Tuesdays, and it won't be voluntary. You'll be a "lawbreaker"
if they catch you, and punished accordingly. Don't wait for that to happen. If we all take some sort of voluntary action now, it
won't have to happen.
Use a bicycle, and/or respect those who do
Bicycles are a great means of transportation. Remember when you were
too young to drive? You didn't think anything of getting
where you needed to go on your bike. It worked just fine. You got exercise, and didn't pollute anything.
We are seeing more and more cyclists on the road these days, but we
tend to resent them. We think that they are in our way.
They are, but they are also cutting down on pollution. Try to think that if they were in a
car, you might not make it through
the next light because they would be in
front of you. Realize that there aren't many good roads for bicycles and that if there
were, the cyclists would be even happier to be on them than you would. Don't think of them as your adversaries. Just be glad
they're not in cars.
Think about riding a bicycle yourself. If it wasn't for the danger of short-tempered, mean-spirited drivers, cycling could be
a great form of exercise -- with a purpose. It's also great for the environment. There are lots of trips you make that would be
ideally suited for a bicycle. If more
of us rode them, then better bicycle routes would be demanded by the taxpayers. This would
make it better all around for both bicyclists and motorists. More people would bike, and less people would drive. More people would
be healthy and feel better, and so would the environment.
Call Ahead
If you aren't sure they have what you want, call stores to find out before you drive there. Don't drive from store-to-store --
call from store-to-store. You can even do price comparisons that way. Call before you "drop-in" on someone to make sure they're
home (they'll appreciate that, anyhow). Using your phone can save you hours of driving, parking and walking around.
Use Your Legs
Why is it, that even if we only live a mile from work, we drive anyhow? Sometimes we have too much to carry, or it's raining,
or we have to do some errands. This isn't true all of the time. The truth is, we just don't think of walking anymore.
Zillions of people are out walking these days -- it's called "recreational walking," and it's all the rage. To do recreational
walking, the rule is, you have to wear special clothes and shoes, and use your "spare" time for it to "count." Right? Wrong. You
can walk in any kind of
clothes (although you might want to wear your "special" shoes and carry your "work" shoes) and actually
save some of your "spare" time for
something else. Try to work walking into your regular schedule, lose weight, feel better and
help the environment.
Recycling Oil
People who change their own automobile oil remove at least 200 million gallons of oil each year. This oil is still useful, if
it is recovered, but only about 10% of it is recovered and recycled. Usually, the oil gets thrown in the trash in containers, or
poured out someplace where it can find its way into our drinking water. This is not only a problem, but a waste, since the oil can
be cleaned up and used again.
Not only does this oil find its way back to our sources of drinking water, it also pollutes our lakes and streams. Used oil
should be put in leak-proof containers.
Different states have different ways of dealing with the oil to be recycled, but in general there are always places to drop
off your used oil. If you don't know of one, call your local garage, or call your city or county to find out how you can have
your old oil reclaimed and recycled. If you don't have time to let your fingers do the walking, at least ask your mechanic for
ideas. Oil is a valuable resource; wars are fought over it. Don't let it be lost for its proper use, and instead be put to the
use of ruining the environment.
Recycling Coolant
Although coolant isn't as bad for the environment as used motor oil, you should still make sure that you dispose of it in the
proper manner. It is very toxic, so keep it away from children and pets. Place it in leak-proof containers and find out where to
take it for recycling. Most cities have oil recycling, but not coolant recycling. Write to your local officials if they don't.
Recycling Tires
This is a tough one, but one that is serious enough for several companies to have begun looking for answers. Something like
240 million tires are discarded in the U.S. each year. These tires pose a very serious threat to the environment. Aside from
taking up huge amounts of landfill space, they tend to rise to the top. Tires catch on fire very easily, and this can result in a
very dangerous situation.
Only about 20% of used tires are suitable for retreading. Some old tires wind up padding docks and swinging in back yards, but
until recently, most of them have just been piling up. Recently, entrepreneurs have been trying to find uses for old tires.
They are shredding them for fuel, mixing them with highway asphalt and using them to soften airport runways. One company uses the
tires for rubber mats, garbage cans and other products.
Since tire disposal costs are skyrocketing, state and city regulations are going to have a big effect on how it's done. Disposal
costs range from twenty five to fifty cents a tire. One state has begun to have a surcharge on new tire sales in order to finance
disposal.
What can you do right now? Try to make your tires last as long as is safely possible. Buy long-lasting, fuel efficient tires.
Check with your dealer about "rolling resistance" and mileage performance before you buy tires. Keep your tires properly inflated,
balanced and rotated.
Don't dispose of tires yourself. If they can't be recapped, give them to the dealer where you buy your new tires and request
that they be properly disposed of.
Recycling Batteries
Old car batteries contain nasty chemicals that can be hazardous to your health. They should not be thrown away, and there's no
need to. The easiest (why take it home with you) way to recycle a battery is to trade it in when you get a new one. Since carrying
auto batteries around is a pretty heavy duty job, this is the best way.
If this method doesn't work out for you, for some reason (most people don't buy new batteries until the old ones quit), get your
yellow pages. Find "Battery Repairing and Rebuilding" and sell it to someone listed there.
Emissions Testing
Many states require emissions tests on vehicles. This means that you drive to a facility where the test people take a sample of
your emissions and run it through some analysis. The results are printed, and you pass or fail depending on the percentage of toxic
emissions that turn up in your car's sample.
The only way to "study" or prepare for this test is to take good care of your car, including its emission system. If you use
preventative maintenance, and keep your car tuned properly, you will pass. If you tamper with your emissions system, you will not
pass. You can have your car checked independently before your emissions test if you want to resolve problems before going to
the emissions test station.
One other good thing to do is to save your printouts from the test from
year to year. If you compare them, you will be able
to monitor your car (if its score is getting worse) and catch any problems before the emissions people catch you. |
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