Air Conditioning Basics: A Quick Reference Guide

Air conditioning systems are crucial to comfort in Southwest Florida, and whether you are installing a new system or having one repaired, it is a good idea to know a few air conditioning basics to simplify the process.

How an Air Conditioner Works

Refrigerant enters the evaporator coil indoors as a cool, low-pressure liquid, where it absorbs heat as a fan circulates indoor air over the coil. This boils the refrigerant, turning it into a gas. Exiting the evaporator, the refrigerant enters the compressor, which increases the pressure of the refrigerant, heating it further, and pumps it through the system.

The refrigerant then enters the condenser coil, where it loses heat and cools to a liquid, using a fan that blows outside air over the coils. Finally, the high-pressure, cool liquid flows through an expansion valve, reducing its pressure, and back into the evaporator to repeat the cycle.

Efficiency Rating

One of the most important air conditioning basics to learn about is the SEER or seasonal energy efficiency ratio. This number indicates how much energy is used by the system over a cooling season, with higher numbers indicating more efficient performance and lower cooling costs. Typical models have a SEER of 13 to 16, while the best have a SEER of 20 or above.


The cooling capacity of a central air conditioner is typically rated in tons, or the ability of the system to remove 12,000 British thermal units, or BTUs, of heat per hour. A 5-ton system, for example, would remove 60,000 BTUs of heat. Smaller air conditioners, like window units, may be rated in BTUs alone.


Central air systems feature a condenser unit, a single evaporator and a system of ducts to deliver air. Ductless systems have an evaporator and air handler in each room, connected to a single condenser, eliminating the ducts and simplifying installation. Heat pumps are similar to central air systems, but can be reversed to provide heat, as well.

For more information on air conditioning basics, contact our team at Conditioned Air today. We serve Southwest Florida, from Bradenton to Marco Island.

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