A/C 101: It Keeps You Cool, But Can You Explain How It Works?

Posted On: September 09, 2012

You do not have to be an air conditioning expert to own one, or to enjoy the cool air it provides. However, understanding the inner workings of your A/C can come in handy at times. So, the air conditioning experts at Ernst Heating & Cooling have put together this little A/C 101 for our Metro-East customers.

First, there are several parts to any A/C system.

  • Refrigerant is the super-cooled liquid/gas that is circulated through the system.
  • The compressor pumps the refrigerant through the A/C in a continuous loop.
  • The evaporator coil, which looks a lot like a car radiator, is what cools the indoor air.
  • The condenser coil is quite similar to the evaporator, but is located outdoors. It actually releases heat into the outdoor air.
  • The expansion valve is a choke point located just before the evaporator coil.
  • An indoor fan or blower pushes air through the evaporator coil and throughout the house, while an outdoor fan blows air through the condenser coil.
  • And, of course, you have a thermostat, which measures the indoor air temperature and tells the A/C when to turn on or off.

Here is how those parts work together to cool your house:

  • Inside the evaporator coil, the refrigerant, which has a boiling point of around 50 degrees below zero, boils and evaporates into a gas. It must absorb heat to boil, which is how the air blowing through the coil gets cooled.
  • The evaporated refrigerant travels to the compressor.
  • The expansion valve only lets a small stream of refrigerant through. So, as the compressor keeps pumping, all of the refrigerant between the compressor and the expansion valve becomes highly pressurized.
  • The condenser coil lies between the compressor and the expansion valve. Since the refrigerant is under so much pressure, it condenses into a liquid. To condense, it must cool, and the condenser coil releases the excess heat to the outdoor air.
  • The small amount of refrigerant that passes through the expansion valve is now under low pressure, which allows it to evaporate and start the cycle again.

If you have any questions, please feel free to contact us at your convenience.

Our goal is to help educate our customers in Hamel, Illinois and surrounding areas about energy and home comfort issues (specific to HVAC systems).  For more information about a/c and other HVAC topics, download our free Home Comfort Resource guide. 

Image courtesy of Shutterstock

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  Fair &...
Recommended in 2015 by neighbors for A/C repair, quick response time in busy season, fair price & friendly...
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Easy to work with!!
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  Well satisfied...
Glad to continue business with Ernst.
by steve l on 06/15/2017
  Just fine. Ok
I prefer to have the same technician from one time to the next so that the person is more familiar with my home. This...
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We had Ernst install a replacement furnace and air conditioner. The install went very smoothly and quickly and the...
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