How Air Conditioners Produce Cold Air – The Steps

July 31, 2020

Close up of a metal grid with a black backdrop. Frozen water droplets hand on the edge of each metal rung.

The Process That Creates Cold Air


Close up of a metal grid with a black backdrop. Frozen water droplets hand on the edge of each metal rung.
Air Conditioners Use Fluid-Filled Compressors To Create Cold Air

Central Air – What is it? 

A/C, Coolant, and distribution

Central air, or ‘air conditioning’, is the process of cooling down warm air with the help of refrigerant chemicals in a compressor. Put simply, a chemical reaction occurs when a liquid turns into gas, and vice versa. In an air conditioners system, a special liquid called ‘coolant’ is forcibly converted from gas-liquid continuously. The resulting chemical reaction absorbs heat, and thus creates cold air. The resulting cool air is then distributed throughout the home structure via ducts depending on the system installed. Overall, the most important aspect of this process is the components in the compressor, which is filled with the refrigerant chemical like freon. 


A neon-green canister filled with freon gas is hooked up to pressure gauges
Freon Is a Refrigerant Gas That Evaporates and Condenses Repeatedly

What is Freon? 

Freon is the most common type of coolant compound found in air conditioning systems. It is a liquid found in evaporator coils, which houses the main chemical reaction responsible for creating cold air. When hot outside air is pulled into the compressor, it passes through these coils. The freon absorbs this heat by becoming a gas, leaving only cool air behind. After, a compressor is used to return the gaseous freon back into a liquid. 

This is achieved by directing all of the heat produced by the first reaction into condenser coils, which convert freon back into a liquid as the hot air is expelled to the outside. 

Can you Run out of Freon?

It is certainly possible that freon can run low- though this usually means that there is a problem with your system. The only way Freon can ever run low is if there is a leak in the system, which is marked by hissing sounds, as well as a notable lack in performance. If you notice that lukewarm air is coming out of your vents despite setting your system to cool air, this may be an indication of a leak. 

Types of Air Conditioning Systems

Simple 2d depiction of a small air conditioner with a remote. Both are against a light blue background, casting a darker blue shadow.
Split Air Conditioners Look Different from the Common Black-Box Design

Central air has two different ways of distributing cold air, each used for a specific purpose.

Split Air Conditioner System-

A split A/C works the same way that a normal integrated central A/C system would work. The difference comes with the separated structure, which is divided into an indoor and outdoor structure. The outdoor structure contains the compressor, condenser coil, and expansion coils, while the interior structure features a fan and air filter to blow the cool air into the unit. In summary, the split A/C still uses the same chemical displacement reaction, but it distributes the cool air differently. 

Packaged Air Conditioner-

The packaged A/C system is the more recognizable of the two. This features duct-distribution (central air), while housing all of the A/C components within one box-like structure located outside of the house. This is the typical black-boxed fan device you see sitting on a concrete slab. 

Like the previous system, the box fan pulls in hot exterior air, which passes over coolant-filled evaporator coils, producing cold air. The cold air is then funneled into a duct system, which distributes cool air all over the house. Indeed, air distribution is related to cooling capacity, which is measured to determine what size of A/C unit is suitable for your home. This varies depending on house size. 

Which is Better?

Both systems have their benefits and disadvantages, however, this is highly dependent on circumstance. 

Package System: Pros vs Cons


  1. A packaged system contains all necessary technologies within one cabinet, often outside. This means it takes up less space and is less noisy. 
  2. Ease of access. Since everything is in one place, any repairs can be done easily. 
  3. Can be put on a roof if conditions are right, saving even more space. 


  1. The distribution of cool air through ducts means it is less energy efficient. Large winding pathways mean there is more opportunity for cool air to escape, or not circulate properly. 
  2. Outdoor A/C cabinets can be damaged by external forces. For example, hailstorms can bend and warp metal structures with their impact. 

Split-A/C Systems


  1. Split systems have a majority of their components located indoors. This means that there is more precision with this system. 
  2. Due to being mostly indoor, there is less chance of the system being damaged by external factors. 


  1. Split A/C systems are complicated to install, requiring professional help. 

Central air is an interesting, and complicated technology that we may take for granted, given how common it is in modern homes. Regardless, it is important to understand these processes in preparation for future disasters. 

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