Environment And Environmental Systems
The Air Conditioning and Heating System
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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