How Does an Air Conditioner Work?

June 5, 2012

Most homeowners have had this happen to them: your AC has stopped working mid-summer and you’re facing an air conditioner repair, but you don’t understand the technician’s diagnosis. What is a compressor and an evaporator coil? Why do they need to be replaced? Whether you’ve always wondered how an air conditioner works or it’s never crossed your mind until right now, Rick’s Heating & Cooling has the answers for you!

Air Conditioner Components

Before we can get into how an air conditioner works, it’s good to have an understanding of the three most important parts of your central AC.

Condenser – This is the portion of your central air conditioning that sits outside your home. It houses the compressor and the condenser coils and contains a network of tubes filled with refrigerant. The refrigerant constantly cycles in and out of your home in liquid and gas form in order to cool the air in your ducts. The condenser has a fan to help it dissipate the heat in the unit.

Compressor – The compressor, located outside your home in the condenser, condenses the refrigerant back into a liquid so it can be cycled back into the home to cool the air again.

Evaporator – Inside your home, you’ll find the evaporator, which has a series of refrigerant-filled tubes that remove the heat and moisture from the air in your home.

How Your AC Works

Diagram of a central air conditioning unit and its components

How an air conditioner works is actually fairly simple. The process mainly involves moving refrigerant—a chemical coolant—from the condenser to the evaporator and back again. We’re going to walk through one cycle, starting in the condenser:

  1. The compressor condenses the refrigerant into a very cold liquid. The heat that has been removed from the refrigerant is blown out of your condenser with a fan.
  2. The refrigerant travels through tubing until it reaches your evaporator. When the refrigerant is in your evaporator, it is extremely cold, around 40 degrees.
  3. Air from your return duct—which is drawn in from the rooms in your home—is pushed upward through your filter and air handling unit by your blower so it can pass over the refrigerant-filled evaporator coils.
  4. As the air passes over the evaporator coils, the refrigerant absorbs the heat and changes into a gas. Since the evaporator coils are so much colder than the air, any moisture vapor in the air condenses on the coil (don’t get confused—this isn’t related to the outside condenser!). If you have proper airflow, the moisture on the coils will roll off into a drain—this is how your air conditioner provides dehumidification. It’s also the reason you need to maintain proper airflow at all times—if you don’t, that water will freeze on your evaporator coil!
  5. The air continues into the supply duct and is recirculated back into your home, approximately 20 degrees cooler than it entered. Often, it takes multiple cycles of cooling before your indoor air reaches the temperature set on the thermostat.
  6. The refrigerant now returns back to the condenser to be compressed and start the cycle over again.

How an air conditioner works and cools your home isn’t overly complicated, it’s just a continuous process of heat transfer. If you have any questions about how an air conditioner works, or if you think your air conditioner isn’t operating properly and you need air conditioner repair in Cincinnati, contact Rick’s Heating & Cooling. We can answer all your questions and make sure your AC is working exactly as it’s supposed to be!