Editing Air conditioning 101

 An Air Conditioner is basically just a heat pump. It cools by removing heat and displacing it to another location.
 Heat is removed by evaporation. If you have ever sat in the yard on a hot day and sprayed the yard around you because it cooled you down, you have experienced evapration at the basic level.
 Evaporation is the same thing as water vapor forming a cloud. Heat applied to water in a puddle for instance will evaporate and the puddle will dry up.That same moisture in a cloud will condense when a mass of cool air moves across it, hence making rain. Really  pretty basic actually.  

It is the same in an Ac system , except the evaporation and condensation occurs within a closed system.


In the AC system you generally have a compressor, a condenser, a restriction or orifice , an evaporator and of course hoses to plumb the system. A drier or drier/filter combination is also used in most applications.
 First...and most important is the compressor. Its job is to generate pressure needed to run the system. As you know , your shop compressor runs your air tools, in an AC system the compressor pressurizes the refrigerant . After the compressor is running , and refrigerant is pressurizing, flow is created and the gas/pressure exits the compressor through the discharge port commonly refered to as the "High side" port, usually marked with an "H" on the compressor.
 Next it flows to the condenser.Gas under pressure, which now is in front of a fan which creates air flow, removes the heat from the compressed gas, which causes it to condense to a liquid, hence the term condenser.Liquid refrigerant flows down the liquid line to the orifice or restriction.
 Now, the next step in the system is the restriction or the orifice which allows the pressure in the system to "back up" or gain pressure as it restricts flow of refrigerant.Some  types  of restrictions are: Pilot operated absolute,thermal expansion valve, and the more common orifice tube.
 The orifice is a precisely calibrated device which meters the amount of rerigerant that passes through it, and also allows the refigerant to build pressure as generated by the compressor.
 Now comes the "Low side" or low pressure side. This is the part of the system that operates after the restriction device. The high side is developed by the   restriction device , but after the restriction you have a lower pressure. This low pressure is created back at the compressors suction side or "Low side". After the restriction the liquid moves into the evaporator which is before the compressor. The liquid Refrigerant enters the evaporator and evaporates. Now  when this happens, the heat is absorbed by the liquid as it evaporates.The Refrigerant then turns back into a gas due to the heat it picks up as it leaves the evaporator, then it gets pulled or "sucked" into the compressor , which is where the term "low side" or "suction Side"  is  from.
 A reciever/ dehydrator  is placed into the system low side to absorb any moisture in the system and it has a chemical inside called a dessicant which is there to keep corrosion in the system in check.
In review , it should go as follows, The compressor pumps refrigerant , creates pressure, which flows to the condenser, where a fan cools it, resulting in the compressed gas turning to a liquid. The liquid then flows throught the restriction device, into the evaporator where it does just that...it evaporates. It picks up heat when it does, creating the desired cooling effect.The gaseous refrigerant then flows to the compressor where it is pressurized,  and passed to the condenser, where the fan cools it, it then condenses and the cycle begins all over again.
 Also as a side note, when you see water running from an AC system it is running from the evaporator unit. It is due to the cooling effect of the freon evaporating inside the system.
 This cooling causes the condesation of moisture in the Air as it passes through the finned part of the evaporator for cooling the inside of the car.When warm moist air is cooled it condenses moisture...hence the water. Kind of like a rain cloud mentioned earlier.

I only briefly mention of  all the parts of the AC system to keep this article as fundamental as possible . It is solely intended to help one understand the basic priciples of an air conditioner.