- You get into your car on a hot day
and ooh, hot, ooh, hot it's too hot.
It's too spicy.
You need to cool off.
You better crank up that A/C.
(upbeat music)
That's right, ladies and gentlemen.
Today, we're talking about one
of the top five inventions of all time,
right up there with computers, vaccinations, pinatas,
and pinatas filled with computers,
vaccinations, and smaller pinatas.
A/C.
And no, I'm not talking about AC adapters
or Lakers legend AC Green
or Bayside High School heartthrob AC Slater.
No, I am talking, of course, about air conditioners.
And more specifically, your car's air conditioning system.
Bazinga.
When most people hear me say air conditioner
they think I'm talking about hair conditioner
because I talk so quietly and my hair looks so good.
(angelic choral music)
But, actually, I'm referring to
the thing in my car that keeps me cool.
No, not my sweet sunglasses.
My A/C.
Alright, a lot of people assume that
the air conditioners in cars are relatively new.
And, well, we know what they say about assuming.
Usually it turns out you're right.
But in this case, you're wrong.
Refrigerants have been around for a while.
Refrigerators from the late 1800s till 1929
used the toxic gases ammonia, methyl chloride,
and sulphur dioxide as refrigerants.
But if they leak, you'd die.
Charles Franklin Kettering,
the guy who invented the first
electric automobile emissions system
was also the Vice President of the
General Motors Research Corporation from 1920 to 1948.
He chose Thomas Midgley to head research
into new refrigerants that wouldn't kill you.
Well, at least not faster than deteriorating in ozone layer.
So in 1928, Midgley and Kettering
invented a miracle compound called freon.
Frigidaire received the first patent for the formula
for chlorofluorocarbons, or CFCs, on December 31st 1928.
1930, General Motors in Dupont formed
the Kinetic Chemical Company that produced freon
and by 1935, Frigidaire and its competitors
sold eight million new refrigerators
in the United States using freon.
By 1939, the same year that World War II was invented
we got automotive A/C.
Air conditioning caught on pretty quick.
It was like somebody invented a way
to stay cool in an uncomfortably hot vehicle.
- Air (stutters) conditioner.
- And now everybody wanted it.
Over half of the new cars sold
came with built in A/C by 1969.
Nice.
Today, we use HCFCs, or hydro chlorofluorocarbons
because they don't screw with the environment as much.
CFCs and HCFCs are used 'cause they go
from liquid to gas and back very easily.
The basic functions of your vehicle's air conditioner
is to cool, remove humidity,
and to allow you appreciate life.
The three main parts of the air conditioning system
are the compressor, the condenser, and the evaporator.
The A/C system is a nearly closed loop system
with a high pressure side and a low pressure side.
Man, all this talk about pressure
reminds me of my favorite Queen song
that I like to listen to when I'm under pressure.
Bohemian Rhapsody.
This is just a normal can of compressed air and right now,
(scanner beeps)
it's at about 73-ish degrees Fahrenheit.
I'm gonna let it discharge.
(can hisses)
(scanner beeps)
Holy mackerel, it's down to 48, 41.
38.
If you Europeans don't know,
32 is the temperature at which water freezes in America.
It's still cooling off.
Ha-ah.
It's pretty cold.
This is beeping so much
'cause the temperature's still changing.
It's fluctuating.
We're into the low teens.
It's freezing.
Before we depressed this canister,
everything inside was a liquid.
When we let it shoot out
it quickly expanded and turned into a gas.
That got rid of all of that energy
and we can measure it by a temperature.
It's kinda what your car's A/C does.
High pressure is high energy.
Allowing the gas to expand
allows it to get rid of that energy.
So we're not really blowing cold air into a car,
we're taking the heat out of it.
Basically, your car's air conditioning is a heat exchanger
moving the heat from the inside of your car to the outside.
But you'll see this as we go through the system.
The high pressure side's closest to the engine.
Why, you ask?
I don't know.
What do I look like, a part doctor?
In the high pressure system we've got a compressor.
This piece runs off a belt attached to the engine.
That belt turns the pistons
inside the compressor's casing.
Refrigerant is drawn into the compressor
in a low pressure gaseous form,
put under pressure, and then is pumped out
as a pressurized gas to the condenser.
Man, I hate it when I have pressurized gas.
It's why I had to stop eating all those spicy foods.
The condenser's basically a radiator
and it serves the same purpose as the one in your car:
To radiate heat out of the system.
Also, it sits right behind the radiator.
But don't call it a radiator, it hates that.
Now, let's get to know it better.
The process of pressurizing the gas
and moving it to the condenser creates heat.
But air flowing around the twisting tubes of the condenser
cools the refrigerant down until it's a liquid again.
Like steam cooling down condensing back into water.
But, before your hairless body can be cool and sweat free
the refrigerant needs to head to the receiver drier
and be prepped for the evaporator.
As the liquid moves out of the condenser
it goes through a little reservoir installed in the line.
And this receiver drier contains desiccants,
small granules that attract water.
There's little packets of desiccants
in the shoe boxes or bags of beef jerky
and they do the same thing,
attract water from the air to keep things fresh.
And the receiver drier desiccants
remove any water that's entered the system
so that ice crystals don't form and damage.
(sighs) Here is where we make
the switch to the low pressure side.
That's exciting.
I haven't been this excited since that time I was
talking about the high pressure side of air conditioners.
I remember like it was three sentences ago.
High pressure is high energy.
Make sure that you subscribe.
If you touch this part of the system
you can feel that it's turned from hot to cold.
The high pressure liquid refrigerant
flows from the receiver drier
through the thermal expansion valve
where it's allowed to expand.
The expansion reduces the pressure on the refrigerant
so it can move into the evaporator.
The valve sense pressure
and regulates the flow of refrigerant
allowing the system to operate steadily.
Moving parts of this valve can wear out
and sometimes they need to be replaced.
Some vehicles got a thing called
an orifice tube instead of an expansion valve.
But it serves the same purpose.
They both allow the refrigerant to expand
and the pressure to be lowered
before the liquid enters the evaporator.
The orifice tube allows the refrigerant
to flow at a constant rate and has no moving parts
but it can become clogged
which is the opposite of my orifice tube
when I eat that spicy food.
Next, we travel to the magical land of the evaporator.
The evaporator's kind of like that spray can that gets cold.
And the expansion valve or orifice tube
is basically the small hole in the air can.
This is the one part of the system
that's usually in the passenger cabin
riding with ya instead of by the engine.
It also looks like a radiator but it's not.
Do not let it hear you say that.
It absorbs the heat from the cabin.
Refrigerant enters the evaporator coil
as a cold, low pressure liquid
and the heat from the cabin turns it back to a gas.
The gas moves out of the evaporator
and out of the passenger compartment of the car,
taking the heat with it.
The fan pulls air from the passenger compartment
and the coils take the heat out of it.
That air then gets pushed through
and blows in your face and cools you off.
(angelic music)
The refrigerant in gas form then enters the compressor
where it's pressurized and the whole process
starts all over again.
The system uses one of those sexy orifice tubes
there's an accumulator between
the evaporator and the compressor
that traps any excess liquid
before it can get into the compressor.
Remember, so it doesn't turn into ice cyrstals?
Guys, stay with me.
The evaporator also takes the humidity
out of the air in the car
and that helps you feel cool
and keeps you from getting moist.
Water in the air condenses on the evaporator coil
along with dirt and pollen
and anything else floating around in the cabin.
So, when you stop the car
and see water dripping underneath, it's not peeing,
it's probably just water from the A/C evaporator
and you don't have to worry about it.
But, if you're concerned that it's oil
or blood or something, just give it a taste.
Don't do that.
But I've done that.
It's like, oh, it's just water.
'Cause sometimes you're like,
uh, er, it's brake fluid, er.
What gave it away?
The fact that it was red and thick, you idiot?
Why'd you taste that?
(clears throat) Okay, so let's review what just happened.
We took the refrigerant and pressurized it,
which heated it up.
Then we passed it across so that it cooled off
so that the air could take some of the heat out of it.
Then, we let it expand.
When it expands, it's now cooler than when it started.
That cool air passes through the cabin
where it absorbs the heat from it
and gets passed to the outside
where it's pressurized, heated up, so it can be cooled.
Make sense?
It's really cool.
(laughs) It's really cool.
That's funny.
'Cause it's about cool air.
But just like a parent's love for a child,
refrigerant doesn't last forever.
If you want you car's A/C to always be
like every car someone's trying to sell on Craigslist
and that is, blows cold,
well, you're probably gonna have to add some refrigerant.
A/C blows cold, gimme a break.
That's how you're selling me this car?
The A/C blows cold?
I need to get to work.
Okay, I'd like to add some refrigerant
to my air conditioning system.
So while we're talking about it,
why don't we just demonstrate how to recharge your A/C?
Come on.
Hey.
- Hey man, what are you doing this week?
- Actually, we're doing air conditioning.
I was hoping I could grab one of those recharge kits.
- Absolutely.
Alright, there you go. - Thanks dude.
- Hey, you need any help we got a ton
of technicians that know what they're doing.
- (laughs) Yeah, I'm a science guy, I think I got this.
- Okay.
(downcast music)
- Is it here? (downcast buzzing)
Here? (happily dinging)
Ah, okay.
(silly whirring)
So if you notice the A/C's blowing a little hot
you can try topping it off with a little refrigerant.
And if that doesn't work take it to a mechanic
'cause it could be clogged and there might be debris.
And they can drain it and they add new fluid.
Sounds like my initiation to Skull and Bones at Yale.
Air Conditioning.
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Don't tell my wife that I sometimes use the car as a sauna.
(rhythmic drumming)