Hot and humid weather in Texas...

Well it's that time of year again. Hot and humid weather in Texas...
I see so many cars driving around with there windows down and it makes me wonder why.
With today's A/C systems and reliability of the systems, there is no need to sweat.
I will explain some major points of A/c systems and there functions along with some new technology's going on in your car.

There are two main reasons that we have air conditioning in cars.
1. Comfort- a/c systems remove the humidity from your vehicle ,which keeps you cooler and comfortable while you drive.It also removes dust and pollens from inside the car, so you breathe easier.
2. Safety- being cooler while you drive keeps you more alert.

Air conditioning systems have been around for over 60 years and some major changes have been seen in the last 10 years. Sixty years ago it was basically a wet towel across a fan. Now days it is a very precise and complex system of electronic controls to regulate temperatures and switches to keep the systems from over pressurizing and damaging the system. new refrigerants so as not to damage the ozone layer, new test equipment to professionally repair these complex systems. And years of training to keep up with all these and future changes in the automotive industry.
All this leads to systems lasting longer with fewer trips to the auto shop for major repairs.

To add to the complications, we now have tough environmental regulations that govern the very simplest of tasks, such as recharging the system with refrigerant R12 commonly referred to as Freon® (Freon is the trade name for the refrigerant R-12, that was manufactured by DuPont). Although it makes it impossible for the weekend worrior to work on there cars due to all the regulations and licesning needed to repair these systems.

Types of Freon: r-12 (The old freon that is banned in the United States), r-134 ( The new refrigerant that is not harmful to the atmosphere ).
And I have heard it said that r-134 is not as cold as r-12. lets get this straight, If done with the proper procedure and equipment. It is colder...

How an a/c system works: Basically, an automotive air conditioning system is split into two sections, a high-pressure side and a low-pressure side (see illustration), which are separated by the compressor (the big thing bolted to the front of your engine with hoses coming out of it) and the expansion valve or expansion tube. Starting at the beginning of the cycle, the compressor pushes refrigerant in superheated gas form through high-pressure lines into the condenser (the thing that looks like a small radiator behind your grille), where cool, fresh air absorbs and carries away most of the heat trapped in the hot gas. As the refrigerant cools off, it condenses, turning into a sub-cooled, high-pressure liquid. The liquid then flows into what is called the drier, a small canister somewhere in the engine compartment that filters out impurities in the refrigerant and separates pure liquid from the gasses.
Next, the sub-cooled, high-pressure liquid leaves the drier and travels to the expansion valve, where it is metered into small droplets that travel through a small orifice into an evaporator or heat exchanger inside the cabin. This effect is similar to placing your thumb firmly over the end of a garden hose and cranking the valve open. Rather than a stream of water pouring out, you get a big cloud of mist. As we discussed earlier, the evaporation process requires quite a bit of heat/energy, so the refrigerant cools down as it moves through the evaporator, which resembles a small radiator mounted in a box somewhere under the dash. Fans circulate warm cabin air through the box and over the fins of the evaporator, where the heat is sucked out of the air and absorbed by the refrigerant. The air temperature drops significantly, and since cool air has less capacity to retain moisture than warm air (that's why Florida in summer is muggy, and Maine in winter is dry), moisture collects on the fins of the evaporator and eventually runs down a drain tube and out the bottom of the car. Finally, cool, dry air is blown out the vents in the dash into your face, while the heated, low-pressure gas travels from the evaporator back to the compressor, where it will be turned back into a high-pressure vapor in order to start the whole cycle over again.