by Joe Brooks

Created on: August 01, 2010

Many of us do not care how an air conditioner works, just as long as it does work. If it fails, we either call the repair technician or get out our tools and start tinkering with it, according to our tendencies and abilities. But if we do care how the thing works, a little understanding of the parts and processes involved in air conditioning will ease our AC anxiety.

An air conditioner of the most common type is much like a refrigerator. The refrigerator is a box with the inside kept cool by refrigeration. Your room, house, or building is a big box with the inside cooled by  refrigeration. The components are about the same, though of course the scale is quite different.

You may wish to know a few air conditioning terms and be aware of the components that are involved. The basic bits are: compressor, condenser, expansion valve, and evaporator coil, along with assorted tubing and fans, with a thermostat to control the conditions inside your own personal refrigerated box. These work together to remove heat from the space and bring cool comfort to the inhabitants.

The first component in the lineup is the compressor. You would expect the compressor to compress something; but what does it compress? It compresses the refrigerant. This used to be Freon, now trending toward more environmentally friendly choices. The compression raises both the pressure and the temperature of the refrigerant. It may seem a little crazy to start the AC cycle by heating something up, but that is how it works.

Next comes the condenser. The refrigerant, coming from the compressor heated up, now passes through the condenser's cools, releases its heat, and becomes much cooler. It seems a little indecisive, heat up, cool down, and so forth, but we will get to the payoff in the end.

From the condenser the refrigerant, now cooled considerably, passes through an expansion valve. The pressure drops dramatically after the refrigerant passes through the tiny orifice of the expansion valve, and as the pressure drops so does the temperature.

The next step is the evaporator coil, where heat is removed from the air, which was the goal in the first place. There is also a reduction of humidity, which causes a feeling of being cooler, as well as the drop in temperature we were all looking for.

This is a simplification of the processes, without discussion of the real technicalities. But you can see what the parts are and what they do. You will also hear about the high pressure side and the low pressure side of an AC system, and you can see the difference as the cycle between the compression and the expansion valve is higher pressure, and the cycle between the expanded refrigerant and the entrance to the compression phase is the low pressure side. That is the AC cycle. Repeat as needed.

Of course there are variations on the theme, and other types of coolers entirely. For instance there are evaporative or swamp coolers that do not use refrigerant. There are also heat pumps, which are a sort of reversible AC, removing heat from your space or warming it up, according to your settings.

Whatever type system you have, it is a good thing to understand at least its basic operating principles. It is also a good thing to understand what you can do as far as maintenance to keep the system operating properly. It is important to have a good air conditioning technician available, just in case things do go wrong. Wherever you are, it would be wise to have the number of your local heating and air conditioning service quickly available. Modern systems, though highly reliable and very efficient, do sometimes need the services of a trained and qualified air conditioning professional.

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