How Your Air Conditioner Works - Part 6

If you are smarter than the average bear, then you want to understand the “whys” and “hows” of your central AC system. That’s the goal of this series of blog posts here at GAMA Air, which we call Air Conditioning 101. We want to help our friends and neighbors in Beverly Hills, Culver City, Mar Vista, Miracle Mile, Hollywood, West Hollywood, Los Angeles, West Los Angeles, Santa Monica, Marina Del Rey, Pacific Palisades, Brentwood, Bel Air, Westwood, Downtown Los Angeles, Vernon, Huntington Park, Sherman Oaks, Encino and the surrounding communities to be comfortable with their knowledge of the inner workings of a typical cooling system, such as the one in your home.

This is now Part 6 of the series. Here’s a rundown of what we’ve covered so far: Part 1 had basic theory of cooling your home. Part 2 brought up the role of the thermostat. Part 3 mentioned the indoor unit and the outdoor unit. Part 4 dug deeper into how refrigerant ties those two together. And most recently in Part 5 of AC 101 we explained the process of moving heat from inside your home to outside your home. But the next question is “Is heat the only thing that is removed from your home?” Let’s dig into that now.

It is true that the goal of an air conditioning system is to provide cooling. And as you already learned about the process of an AC unit, cool air is not made but instead heat is moved from one place to another. In the case of a residential central AC unit, the heat is obviously moved from inside the home to the outside. But there is something else happening during this heat transfer process. And it is a key to the comfort of you and your family in your home.

You will recall from Part 5 that we used an illustration of what happens on the surface of a cold drink on a hot day to explain what happens inside the ‘outdoor unit’. The refrigerant is in a gas form, but then it condenses into a liquid as heat is pulled out of it and blown into the air outside. However, that process of condensing is happening somewhere else, namely inside your indoor unit.

We already explained that the refrigerant in the indoor coil is boiling off, turning the liquid refrigerant into gas refrigerant. But what about the air that is passing through the coil? The warm air is making the refrigerant go from liquid to gas as heat is pulled out of it. To the touch the indoor coil is cold. And do you remember what happens on cold surfaces when the air is warm? Remember the coaster under your cold drink to catch the water dribbling down the side of the cold glass? That’s what is happening to the air inside your indoor unit. Moisture from the warm air in your home is condensing on the cold coil.

Here’s what that means in practical terms. It is a hot muggy day, and the AC has been off while you were away from home. When you get home, you flip on your AC and can feel cool air blowing out the vents. But after a while the temperature on the thermostat has barely changed. You know your air conditioner is working at its best because you just had it tuned up. What’s going on? Your AC is first pulling excess moisture out of the air. The truth is moisture holds heat much better than air alone does. That’s why humid air can feel warmer than dry air. So, it might take a while after you turn on your AC for you to see the temperature drop on the thermostat. As the humidity level inside your house drops, then you will see the temperature come down also.

Getting that moisture out is an important part of a properly operating AC system. But where does it go? That’s coming up next, so stay tuned!

Need help with a question you have? Visit our Ask an Expert page and get a quick answer from the resident expert here at GAMA Air.

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