~Air Conditioning~

Just about every modern car, truck or SUV sold these days can be had 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 — presto! — 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 job interview in Phoenix, Ariz., if your car didn't have air conditioning? By the time you got to your interview, 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 gasoline to make yourself feel cooler? It's weird to think that by burning something you become cooler, but it's true.

Here's a simple example of evaporation. Imagine that you're swimming around in your neighbor's 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 vapor. And as it evaporates, it draws heat away from your body, and you get goose bumps. Brrr! Now let's say your neighbor hands you a big glass of ice-cold lemonade. 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 vapor the air is carrying condenses into water.

Both of these examples occur at normal atmospheric pressure. But higher pressures can also change a vapor (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 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.

Here's how an air conditioning system and its components work.

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 vapor under high pressure and high heat to the condenser.

Step Two: The condenser is a device used to change the high-pressure refrigerant vapor 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.

Step Three: Refrigerant moves to the receiver-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 vapor in the evaporator.

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 vapor 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. 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 compressor clutch
  
• Defective expansion valve
  
• Clogged expansion valve, receiver-drier or liquid refrigerant line
• Blown fuse
  
• Leaking component: any of the parts listed above or one of the A/C lines, hoses or seals

~Insufficient Cool Air~

• Low refrigerant charge
  
• Loose drive belt
  
• Slipping compressor clutch
  
• Clogged condenser
  
• Clogged evaporator
  
• Slow leak in system
  
• Partially clogged filter or expansion valve
  

Most A/C repairs are best left to a repair shop. 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. Some heating, ventilation and air conditioning systems also engage the A/C compressor for defrost mode (for example, most GM vehicles).


~Pressure Blowers ~



~Unit Heaters ~



FRP-General-Purpose Fume Exhausters

Selecting Air Conditioner Components

Split system air conditioners contain various components that must be matched up accordingly. We have a special Kit Builder to help you select all the right components.

In a split system, the compressor and condenser coil (contained in a standard unit or heat pump), are installed outside the home, and the evaporator coil is installed inside the home in the plenum of a forced-air furnace or air handler. The indoor and outdoor components of a split-system are usually connected by two refrigeration lines and a low-voltage relay cable.

The following components make up a split system:

	Standard Unit (Condenser) or Heat Pump A condensing unit is the main component of central air conditioning, and is the part that sits outside the home. Inside it is a pump called a compressor, coils, fan and electrical system. The condenser comes entirely pre-assembled and pre-charged with Freon. When a standard air conditioning system (with a condensing unit) is operated, the condenser in the yard gets warm and the evaporator coil in the furnace gets cold, thereby cooling the home in summer. With a heat pump, the same happens in summer, but in winter, the reverse occurs: the outside condenser gets cold and the inside evaporator coil inside the air handler gets warm, thereby heating the home. Heat pumps work best in climates where winter temperatures do not regularly fall below 25 degrees Fahrenheit. Most homes in central and northern states use standard systems, and in the south, both standard and heat pumps are popular.
Evaporator Coils An evaporator coil is the part of an air conditioning or heat pump system that becomes cold when the unit operates. It is connected to the ductwork of the home. When the system is on, air flows through the coil and the cold air is distributed throughout the home. Evaporator coils are either cased or uncased and must be matched up with the condensing unit or heat pump to ensure proper operation of your air conditioning system. You will need only one of the following three types:
	Cased Evaporator Coils Cased evaporator coils are used primarily if you are purchasing a new furnace. Cased coils and furnaces sold on our site must be matched up for an exact fit.
	Horizontal Evaporator Coils Horizontal evaporator coils are used when you have a furnace that is mounted horizontally.
	Uncased Evaporator Coils Uncased evaporator coils are used primarily if you already have a furnace and will be inserting the coil in your pre-existing ductwork.
	Condensing Unit Pad Pads are simply a base for the outdoor air conditioner or heat pump to sit on. They are made of 2-inch thick plastic and are very rigid. The plastic is made with ultraviolet inhibitors so it will not break down in sunlight. Pads come in different sizes, fitted for your particular condensing unit or heat pump.
	Electrical Disconnect A disconnect is a safety on/off electrical switch mounted on the home near the condenser or heat pump. It is required by electrical code, and is a good idea for safety and system servicing purposes.
	Refrigerant Line Sets Line sets consist of two semi-flexible copper pipes to connect the outdoor air conditioner or heat pump to the indoor evaporator coil. The smaller pipe is called the liquid line. The larger pipe is referred to as the suction line and includes insulation. The liquid line diameter for all systems is 3/8 inches in diameter. The suction line diameter will be either 3/4, 7/8 or 1 1/8 inches, depending on the size and efficiency of the air conditioner or heat pump. Line sets come in several lengths and are designed to be cut to fit your exact needs.
	Electrical Whips Electrical whips are simply wires in a weatherproof casing for outdoor use. They are used to connect the 220-volt power to your outdoor air conditioner or heat pump. A typical installation requires two electrical whips. Whips come in two wire size thicknesses (gauges), No. 10 Gauge or No. 8 Gauge and are used depending on which system size and efficiency you choose.
	Installation Supplies Packages Alpine Home Air Products Supplies Packages make your air conditioning or heat pump installation easy! They include nearly all the miscellaneous materials needed for the job. If you are using an uncased evaporator coil, choose a supplies package that also contains pre-fabricated sheet metal for a fast and easy coil installation. All supplies packages include our exclusive 1-hour installation instructional video that clearly shows you how to install your own air conditioning system successfully.