The condensed, pressurized, and still usually somewhat hot liquid refrigerant is next routed through an expansion valve (often nothing more than a pinhole in the system's copper tubing) where it undergoes an abrupt reduction in pressure. That pressure reduction results in flash evaporation of a part of the liquid refrigerant, greatly lowering its temperature. The cold refrigerant is then routed through the evaporator. A fan blows the interior warm air (which is to be cooled) across the evaporator, causing the liquid part of the cold refrigerant mixture to evaporate as well, further lowering the temperature. The warm air is therefore cooled and is pumped by an exhaust fan/ blower into the room. To complete the refrigeration cycle, the refrigerant vapor is routed back into the compressor. In order for the process to have any efficiency, the cooling/evaporative portion of the system must be separated by some kind of physical barrier from the heating/condensing portion, and each portion must have its own fan to circulate its own "kind" of air (either the hot air or the cool air).
Air conditioners improperly installed will develop air duct leaks and low air flow. Your air conditioner looses its cooling power in hot weather. A lack of maintenance will cause your air conditioner to malfunction. Refrigerant charges and compressors are some of the parts needing regular maintenance. Regular maintenance increases the lifespan and production of your air conditioner.
In 1995, Germany made CFC refrigerators illegal. DuPont and other companies blocked the refrigerant in the U.S. with the U.S. EPA, disparaging the approach as "that German technology". Nevertheless, in 2004, Greenpeace worked with multinational corporations like Coca-Cola and Unilever, and later Pepsico and others, to create a corporate coalition called Refrigerants Naturally!. Then, four years later, Ben & Jerry's of Unilever and General Electric began to take steps to support production and use in the U.S. In 2011 the EPA decided in favor of the ozone- and climate-safe refrigerant for U.S. manufacture.
Just like running a marathon, we perform better at full strength. If we’re not feeling great, it’s that much harder to finish the race. Similarly, when you set your thermostat to a certain temperature, the system is tasked with maintaining that temperature throughout the room. Working at full strength, the system can easily maintain that temperature (as long as it’s not below 60 degrees or above 80 degrees). However, when injured, the system may struggle to keep the room at your desired temperature. As such, it’s working harder, which means higher utility bills.
If you have a good HVAC contractor they should offer an annual preventive maintenance agreement where they will perform semi-annual maintenance, once in the Spring and once in the Fall, to service your heating and cooling system. The typical maintenance agreement usually guarantees the HVAC contractor will provide service and parts at a discount rate if the listed equipment fails. Some contractors will even give you after hours service with no extra overtime charge as is the case with most other customers.
If your air conditioner isn’t cooling, or is experiencing another performance issue, shut it off. Don’t continue to operate a malfunctioning air conditioner, as that may worsen the problem at hand. This is one reason we do preventative maintenance checks pre-season – a technician identifies and corrects problems, so you don’t run your system with faulty components, causing more damage.
In 1758, Benjamin Franklin and John Hadley, a chemistry professor at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids (such as alcohol and ether) could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to speed up the evaporation. They lowered the temperature of the thermometer bulb down to −14 °C (7 °F) while the ambient temperature was 18 °C (64 °F). Franklin noted that, soon after they passed the freezing point of water 0 °C (32 °F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about 6 mm (1⁄4 in) thick when they stopped the experiment upon reaching −14 °C (7 °F). Franklin concluded: "From this experiment one may see the possibility of freezing a man to death on a warm summer's day."