The external section of a generic single-room air conditioning unit. For ease of installation, units are typically fitted into windows or, as in this photograph, a hole in the wall The internal section of the same unit. The front panel swings down to reveal the controls. An air conditioner is a system or a machine that treats air in a defined, usually enclosed area via a refrigeration cycle in which warm air is removed and replaced with cooler and more humid air. In construction, a complete system of heating, ventilation, and air conditioning is referred to as HVAC. Whether in homes, offices or vehicles, its purpose is to provide comfort by altering the properties of the air, usually by cooling the air inside. The 19th century British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Philippines physician Dr. John Gorrie used compressor technology to create ice, which he used to cool air for his patients.

[1] He hoped eventually to use his ice-making machine to regulate the temperature of buildings and even considered cooling entire cities with  a system of centralized air conditioning units. Air conditioning engineers broadly divide air conditioning applications into comfort and process. Comfort applications aim to provide an indoor environment that remains relatively constant in a range preferred by humans despite changes in external weather conditions or in internal heat loads. Process applications aim to provide a suitable environment for an industrial or a commercial process, regardless of internal heat loads and external weather conditions. Although often in the same comfort range, it is the requirements of  the process that determines conditions, not human preference. In both comfort and process applications, the objective is not only to control temperature (although in some comfort applications this is all that is controlled) but also factors like humidity, air movement and air quality.

A simple stylized diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporator coil, 4) compressor. In the refrigeration cycle, a pump transfers heat from a lower temperature source into a higher temperature heat sink. how to repair an ac unitHeat will naturally flow in the opposite direction. ac unit for single roomThis is the most common type of air conditioning. need new hvac unitA refrigerated air conditioning system works in much the same way pumping heat out of the room in which it stands. This cycle takes advantage of the universal gas law PV = nRT, where P is pressure, V is volume, R is the universal gas constant, T is temperature, and n is the number of molecules of gas (1 mole = 6.022×1023 molecules).

The most common refrigeration cycle uses an electric motor to drive a compressor. In an automobile the compressor is driven by a pulley on the engine's crankshaft, with both using electric motors for air circulation. Since evaporation occurs when heat is absorbed, and condensation occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a coolant around an enclosed system. The cooling liquid, or refrigerant is pumped into the cooled compartment (the evaporator coil). Low pressure then causes the refrigerant to evaporate taking the heat with it. In the other compartment (the condenser), the refrigerant vapour is compressed and forced through another heat exchange coil, condensed into a liquid which then rejects the heat previously absorbed from the cooled space. Air conditioning has as much influence on human health as any generic heating system.Poorly maintained air-conditioning systems (especially large, centralized systems) can occasionally promote the growth and spread of microorganisms such as Legionella pneumophila, the infectious agent responsible for Legionnaire's disease.

[2] Air conditioning can have a positive effect on sufferers of allergies and asthma. In serious heat waves, air conditioning can save the lives of the elderly. Some local authorities have even set up public cooling centers for the benefit of those without air conditioning at home. ↑ History of Air conditioning ↑ Sick building syndrome ↑ Home Control of Asthma & AllergiesMy room is TOO HOT! I need free-standing AC unit! April 8, 2010   Subscribe Please recommend a good portable air conditioner (non window mounted, freestanding most preferred) to cool my ridiculously hot room down. ▲Air Wisconsin Airlines Corporation air your dirty laundry in public Air, Land and Sea air, law of the Air, Noise, & Radiation Health Research Division Air, Noise, and Radiation Programs Air, Pesticides and Toxics Management Division Air, Rail, Water, and Pipeline Air, Resource Conservation and Recovery Act and Toxics Division Air, Space and Cyberspace Constructive Environment

Air, Toxics & Radiation Monitoring Division Air, Trees, Water, Animals Air, Water, and Aquatic Environments Science Program Air-Actuated Hydraulic Swaging UnitThe Summer Crisis Program begins July 1st and ends August 31st. The Summer Crisis Program is for electric utility assistance only and is for households that include a person 60+ years, customers with a household member who has a qualifying medical condition or households served by a non-regulated utility with disconnect notice. The maximum amount for bill payment assistance and/or air conditioner is $300 for regulated utilities and $500 for non-regulated utilities. To qualify for the Summer Crisis Program, households must be at or below a gross annual income of 175% of the federal poverty level and meet one of the following criteria: You do not have to be enrolled in PIPP to be eligible for the Summer Crisis Program. You do not need a disconnect notice to be eligible for the program. The benefits of the Summer Crisis Program include provision of one window air conditioning unit per household (for households that do not have central air and have not received an air conditioning unit in the past three years {2013, 2014, 2015} and/or a one-time payment of up to $300 on the electric bill for regulated utilities and $500 for non-regulated utilities.)

Medical eligibility for an air conditioner is needed for anyone under the age of 60. You must have written documentation: a prescription from your doctor, Nurse Practitioner, or you can see our Lung Health Clinic (Monday or Wednesday). There are a limited number of air conditioners available. **PLEASE BE ADVISED OF THE FOLLOWING ADDITION TO DOCUMENTATION NEEDED**: To make an appointment at our main office Interactive Voice Response System,  24 hours a day,   holidays, weekends or workdays at: 1-866-861-6399 To make an appointment at all of our other locations call: 614-566-0750 The main office accepts the first 25 walk-ins from 8:30 am to 10 am, Monday through Friday. Our hours of operation for appointments are 10 am to 4 pm and Wednesdays until 6 pm. Neighborhood location visits are by appointment only. See site locations for hours. All offices are closed between 12 pm and 1 pm, Monday through Friday and all day on state and federal holidays. An application for assistance must be completed at our main office or at one of our neighborhood locations