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Air Conditioner Basics - How They Work

Updated: Jul 5

Understanding the basics of air conditioning can help you better maintain your system and ensure it operates efficiently. Let's break down how central air conditioning works and what makes it an essential part of home comfort.

Basics of Air Conditioning

Most people believe that an air conditioner functions by pumping cool air into their home. However, an air conditioner removes warm air and recirculates it as cool air. Essentially, an air conditioner operates similarly to a refrigerator, using the evaporation of a refrigerant like Freon to provide cooling. A central air conditioning system includes cooling and heating of air, cleans the air, and controls moisture levels. If you're looking to upgrade your system, check out the latest air conditioner specials available.

How Air Conditioning Systems Work

Removing Warm Air

Every central air conditioning system has the same basic components: a method to remove warm air to create cool air, a distribution system (typically ducts), and a control system (thermostat). Alternatively, a wall air conditioner can be a more compact option, offering similar cooling benefits without the need for extensive ductwork.

Temperature Control

The first component is temperature control. When the air temperature rises above a preset level on your thermostat, the thermostat sends a signal to the air conditioner to turn on. If you need a new unit, many air conditioners for sale offer advanced temperature control features.

The Compressor: The Heart of the System

The air conditioner compressor, controlled by the thermostat, acts as the pump. It causes the refrigerant to flow through the system. It draws in low-pressure, low-temperature refrigerant gas and compresses it, raising the pressure and temperature of the refrigerant. This high-pressure, high-temperature gas then flows to the condenser coil.

Central AC System of The air conditioner compressor, controlled by the thermostat, acts as the pump. It causes the refrigerant to flow through the system. It draws in low-pressure, low-temperature

The Condenser Coil

The condenser coil, a series of pipes with a fan, draws outside air across the coil. As the refrigerant passes through and the cooler outside air passes across the coil, the air absorbs heat from the refrigerant, causing it to condense from a gas to a liquid state. The high-pressure, high-temperature liquid then reaches the expansion valve. This process, along with other essential air conditioner parts, ensures the system's efficiency and effectiveness.

The Expansion Valve: The Brain of the System

The expansion valve senses the temperature of the evaporator or cooling coil. It allows the liquid refrigerant to pass through a small opening, causing it to expand to a low-pressure, low-temperature gas. This cold refrigerant flows to the evaporator, where an isolator for the air conditioner can help reduce vibration and noise.

The Evaporator Coil

The evaporator coil, connected to a furnace or air handler, blows indoor air across it. This causes the coil to absorb heat from the air. The cooled air is then delivered throughout the house via ducting. The refrigerant then flows back to the compressor, starting the cycle over again.

Components of a Central Air Conditioning System

Split System

Most central air conditioning units operate as a split system. This means they consist of a "hot" side (the condensing unit, including the condenser coil, compressor, and fan) situated outside your home and a "cold" side inside your home. The cold side consists of an expansion valve and a cold coil, usually part of your furnace or an air handler. The furnace blows air through an evaporator coil, cooling the air, which is then routed through your home via air ducts.

Heat Pumps and Geothermal Systems

Heat pumps and geothermal systems also cool your home by removing warm air and replacing it with cool air.

Efficiency Ratings

Understanding how air conditioning systems are rated for efficiency is important. They are rated by the Seasonal Energy Efficiency Rating (SEER). Air conditioners with a higher SEER are more efficient, less costly to operate, and more environmentally friendly. The current government minimum is 13 SEER.


The basics of your cooling system include the thermostat for control, the central air conditioning unit to remove warm air to create cool air, and a duct system to distribute the air through your home. This is how your central air conditioning system keeps you cool and comfortable. When considering upgrading or installing a new system, it's essential to compare air conditioner prices to find the best option for your needs and budget.


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