How Air Conditioners Work The first modern air conditioning system was developed in 1902 by a young electrical engineer named Willis Haviland Carrier. It was designed to solve a humidity problem at the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, N.Y. Paper stock at the plant would sometimes absorb moisture from the warm summer air, making it difficult to apply the layered inking techniques of the time. Carrier treated the air inside the building by blowing it across chilled pipes. The air cooled as it passed across the cold pipes, and since cool air can't carry as much moisture as warm air, the process reduced the humidity in the plant and stabilized the moisture content of the paper. Reducing the humidity also had the side benefit of lowering the air temperature -- and a new technology was born. Carrier realized he'd developed something with far-reaching potential, and it wasn't long before air-conditioning systems started popping up in theaters and stores, making the long, hot summer months much more comfortable [source: Time].

The actual process air conditioners use to reduce the ambient air temperature in a room is based on a very simple scientific principle. how much electricity does an ac unit costThe rest is achieved with the application of a few clever mechanical techniques. how much does it cost to replace a ac unitActually, an air conditioner is very similar to another appliance in your home -- the refrigerator. parts of an central ac unitAir conditioners don't have the exterior housing a refrigerator relies on to insulate its cold box. Instead, the walls in your home keep cold air in and hot air out. Let's move on to the next page where we'll discover what happens to all that hot air when you use your air conditioner.

In this article, we'll show you how to clean and maintain your central air conditioner to keep it running efficiently. We won't demonstrate the maintenance steps for a window-mounted model here. Most central air conditioners have two basic parts: an outdoor unit (compressor/condenser) that sits next to your home and an indoor unit (evaporator) that's located in a central duct near your furnace (Fig. A). If you have a heat pump instead of a furnace, the indoor unit will be in the air handler. Use the same maintenance steps we show here. If your furnace looks different from the one in Fig. A, or you have a heat pump, use the owner's manual to find your way around it. The basic parts will be the same. The most important maintenance steps are fairly simple, but if this is the first time you've cleaned the unit, allow about a half day to carefully work through the steps. If you're not up to the task, call a pro (look under “Air Conditioning Contractors” in your Yellow Pages). Cleaning and servicing a central air conditioner costs $100 to $250.

Fig. A shows a typical central air conditioning/furnace setup. Two copper tubes connect the outdoor compressor and its condenser coil (a “coil” is a combination of fins and tubes) to the indoor evaporator coil that's located in the plenum (Fig. A) above the furnace blower. One tube is covered with foam insulation. If you have a heat pump, both tubes will be insulated. Outside, your main job is to clean the condenser coil (Photos 2 - 4). The fan inside the condenser coil sucks air through the fins, and as a result, pulls dirt and debris with it. Dust, leaves, dead grass and anything else that collects on the fins will block airflow and reduce the unit's efficiency. Grass clippings thrown by the lawn mower and “cotton” from cottonwood trees and dandelions are particularly bad offenders. You might have to clear the fins weekly or even daily during the spring “cotton” season! Always begin by shutting off the electrical power (Photo 1). Then proceed with the cleaning (Photos 2 - 4).

If the fan motor (Photo 3) has lubrication ports, apply five drops of special oil for electric motors (not penetrating or all-purpose oil). You can find oil for electric motors at hardware stores. Many fan motors are maintenance-free—they don't have oil ports (ours doesn't) and can't be lubricated. Check your owner's manual if unsure. The compressor and its motor sit inside the coil (Fig. A). They're usually sealed and won't need maintenance. However, if you have an older compressor that's belt-driven by a separate motor, lubricate the motor through its oil ports. In every case, keep an eye out for dark drip marks on the bottom of the compressor case or pad (Photo 5). This indicates an oil leak; the compressor or tubes might be leaking coolant (refrigerant) as well. If you find a leak, call in a pro to check the problem. Don't tighten joints to try to stop leaks yourself! Over-tightening can make the problem worse. And only a pro with proper equipment can recharge the system to the proper level of coolant.

There are times when I am extremely thankful for air conditioning -- usually after I have had a long workout on a hot summer's day and am still sweating after a cold shower. The cold, dry air is invigorating and refreshing. But usually, after about 30 minutes, I find myself shivering and needing to go back outside. Indeed, I have found that the majority of homes I have visited and more so, public offices and stores, the air conditioning temperature is set so low that I find myself feeling sick so that I have to step outside. I also find that I am more tired and my muscles more sore from shivering all day. So I decided to look into why this is and what we should all know about air conditioning. To begin, I do contest to the positive side of air conditioners, as they are beneficial to those individuals who suffer from asthma and allergies, as pollen and dust are filtered through the system. The air conditioners also dry out the humidity and usually clean out the air, enabling us to breathe cleaner air and not be over-run by heat stroke.

The problem is, however, that these systems need to be extremely well-maintained, checked and cleaned, or all these benefits are trumped by breathing problems and infections. More so, keeping the room temperature so cold has other negative consequences. These are the top five negative health consequences that you want to be aware of:When air conditioners are not cleaned thoroughly and filters changed, a breeding ground for all kinds of bacteria and fungi is created. These systems especially can be home to black mold, as moisture can build up in the coils and ducts from condensation that forms when the cool air passes through. When these microorganisms go air-borne, they can lead to a multitude of breathing problems, including a potentially fatal infectious pneumonia, Legionnaire's disease, caused by the bacterium Legionella pneumophila. Remedy: Make sure your air conditioning systems are cleaned regularly and the filter changed every few months. 2. Fatigue, headaches and generally feeling ill.

Many individuals find that after a day of work, they often feel more tired than usual, headachy and a general sense of malaise. They also find that once they leave the building, the symptoms often resolve. Sometimes termed "sick building syndrome," it may be that air conditioning may be the cause. In a study published in the Aug. 19, 2004 International Journal of Epidemiology, people working in office buildings with central air conditioning had more symptoms of illness than those who did not work in buildings with central air. Remedy: Raise the temperature slightly so that you are not shivering and take regular breaks to step outside for fresh air and for your body temperature to equilibrate.The Environmental Protection Agency (EPA) is warning us that we may be more exposed to pollutants inside than outside, especially because central air conditioning does not bring in fresh air but circulates old air. This means that if there is mold, dust, animal dander or other people in the building have viruses or air-borne infections, individuals are more prone to be exposed and get sick.