Getting to know your A/C System

Updated: Jun 25, 2020

Welcome to the Green Energy & Air Tech blog! This is the first in a series of posts about getting to know your air conditioner.

The Basics

If you are anything like me, you take something like your air conditioner for granted....until it's a 90 degree day and it doesn't want to turn on!

Why didn't I get my A/C serviced?

Panic sets in. You're going to have to hire someone to fix it.

Is melting to death an option?

Fear not dear reader!

Knowledge is power! Today I am going to teach you about the wonders of your homes cooling system!

Modern air conditioners are made up of indoor and outdoor components. The indoor part pulls in hot air and cools it and the out door part sucks hot air out of the house.

Now was that so complicated?


Cause there's MORE!


An air conditioner has 5 main parts:

  • Refrigerant

  • Condenser coils

  • Evaporator coils

  • Compressor pump

  • Expansion valve

X= Expansion Valve E=Evaporator Coils F=Fan P= Pump G= Grill


Refrigerant is a chemical that produces a cooling effect while expanding into a liquid or or vaporizing into a gas. It travels in a loop, through the indoor and outdoor portions of an A/C system. As it travels around your air conditioner, it changes from a gas to a liquid, and draws heat out of the air inside your home. The now heated refrigerant flows out of your home and takes the heat with it.

After it carries the heat outside, it cools down and becomes a gas again. It is pushed back inside the house and further cooled and recirculated.

For an air conditioning system to operate with economy, the refrigerant must be used repeatedly. For this reason, all air conditioners use the same cycle of compression, condensation, expansion, and evaporation in a closed circuit. The same refrigerant is used to move the heat from one area, to cool this area, and to expel this heat in another area.

So you may be wondering, how does the refrigerant actually move around the A/C?

The Condenser And Evaporator Coils

That's how!

The Evaporator Coils

After the refrigerant is returned to the inside portion of the unit, after being made into a cold liquid state again, a fan (F1) blows over the copper tubes of the evaporator coils. This is what draws the heat in from your home, because heat naturally flows from hot to cold. As the refrigerant absorbs the heat from inside, it becomes a gas and flows to the outside tubes called

The Condenser Coils

The condenser coils perform the opposite job of the evaporator coils. When the refrigerant is pushed into the condenser coils outside the house, it has been super heated by the compressor pump. The condenser coils carry the heated refrigerant outside the home where the heat it carries can be distributed, before pushing it back into the home through the expansion valve.

So what do the compressor pump and expansion valves do anyway?

The Compressor Pump

In order for the refrigerant to draw heat to the outside of your home, it needs to be hotter then the air outside. Remember when we said that hot air tends to flow towards cooler air? That's called heat transfer.

To get the refrigerant to a hot enough temperature, it is passed through the compressor pump. There, the refrigerant is pressurized, which raises the temperature of the refrigerant to around 160 degrees


The Expansion Valve

After the refrigerant distributes the heat outside in the condenser coils, it has been cooled down a bit, to around 130 degrees Fahrenheit, by having air blown over it from the condenser fan(F2). But it is still too hot to be returned back to the evaporator coils. After the condenser coils, the refrigerant goes through the expansion valve, where it experiences a pressure drop. This drop in pressure cools it down enough to be returned to the evaporator coils. Then, the refrigerant draws heat from the evaporator coils which causes the refrigerant to vaporize. The evaporator draws heat from the room that is to be cooled. The vaporized refrigerant goes back to the compressor pump, and the cycle starts again.


Here's what we learned today!

  1. Air conditioners contain refrigerant, which are chemicals that draws heat out of the air as they change from a gas to a liquid state.

  2. The refrigerant flows in a loop around the entire unit, which has indoor and outdoor parts.

  3. The refrigerant flows through small pipes or "coils", the condenser coils on the outside of the house and the evaporator coils inside the house.

  4. The refrigerant works on the principal that heat is drawn to cooler areas.

  5. The refrigerant is cooled before it is returned to the evaporator coils in the expansion valve, where it is depressurized enough to go back into the evaporator coils.

  6. When it is in the evaporator coils, the refrigerant is cooled further by having air blown over it from the evaporator fan and becomes cooler then the air in the room. It draws heat from that air on its way to the compressor pump. So you get cooling from the fan blowing and from the heat and humidity being drawn from the room.

  7. The compressor pump pressurizes the refrigerant until it becomes much hotter then the outside air, which draws more heat outside the home, as it is pushed into the condenser coils.

  8. In the condenser coils, the pressurized refrigerant disperses the heat to the outside, and it is blown by the condenser fan to cool it down before it is returned to the expansion valve

It's the ciiiircle of cool! And it keeps us un-sweaaaty!

Well readers, I hope you enjoyed this blog post and stay tuned for the next post on how to keep your A/C unit running in peak condition!

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