Whether you own a heat pump, central air unit or ductless mini split, they all share a common purpose: to cool your indoor space. When you adjust the thermostat on a hot afternoon, you want to make sure that your cooling system responds. But how does it respond? Although you may have long enjoyed the comfort and convenience of your air conditioner, you may be wondering at where that cool air comes from, if not from a block of ice. The process is complicated but having a basic understanding of how air conditioners work is useful. It may help you catch a problem before it becomes a major issue.
The fundamental process behind many of the most popular refrigeration systems, from central air to walk-in coolers is more or less the same. It involves the transfer of thermal energy by means of a refrigerant cycle. Let’s start with a standard central air split system, so-called because it splits the system into an outdoor unit and an indoor unit. Packaged units (wherein all components are housed in the same quarters) are more popular in commercial applications. Let’s begin with the compressor, which is a pump located in the outdoor unit along with the condenser coil. It takes the low temperature, low pressure gas fresh from its interaction with your warm air in the evaporator coil and it pressurizes it. This radically increases the temperature and pressure of the gas so that it can disperse this thermal energy as it goes through the condenser.
As its name suggests, the condenser coil and blower fan work in tandem to cool this gas, thus turning it into a liquid. It has lost a significant amount of thermal energy originally taken out of your indoor air, but not enough to cool your air. In order to drop the temperature further, your liquid refrigerant enters an expansion valve where it is depressurized and cooled dramatically. It is now primed for cooling purposes. It heads indoors where it circulates through the evaporator coil. The interaction between the cold refrigerant in these coils and your warm indoor air extracted from your living space is the key to the cooling. The refrigerant absorbs the thermal energy of your air and cools the air in the process. Your cooled air is then distributed throughout your home.