Get to Know your Air Conditioner

It’s air conditioning season, and by now you’ve probably had your checkup done, you’ve got your A/C unit cranked up, and it’s keeping you cool and dry during these hot, humid summer days. You’re probably not thinking much about how it works, what the parts do, and how they work together to keep you comfortable. Of course, here at Action Air, we think you should know as much as possible about your HVAC system so that you can keep it operating smoothly and efficiently. So in the next couple of posts I’d like to go over the basics of air conditioning and heat pump cooling.


Most people think that air conditioners lower the temperature in their homes simply by pumping cool air in. What’s really happening is that the warm air from your house is being circulated through the air handler and cycled back in as cooler air. This cycle continues until your thermostat reaches the desired temperature.

Air conditioners work in the same way as refrigerators. Of course, instead of cooling just a small space, an air conditioning system cools a whole house; but the principle is the same. Air conditioners use chemicals, or refrigerants, that convert from a gas to a liquid and back again. This chemical is used to transfer heat from the air inside of a home to the outside air.

The unit has three main parts– a compressor, a condenser and an evaporator. The compressor and condenser are usually on the portion of the air conditioner that is located outside the home. The evaporator is located on the inside the house, often as part of your heating unit.

The evaporative cycle is the action that produces cool air in your home:

1.The compressor compresses cool refrigerant gas, causing it to become hot, high-pressure gas.

2.This hot gas runs through a set of coils so it can dissipate its heat, and it condenses into a liquid.

3.The refrigerant liquid runs through an expansion valve, and in the process it evaporates to become cold, low-pressure gas.

4.This cold gas runs through a set of coils that allow the gas to absorb heat and cool down the air inside the building.

In order to circulate the cool air throughout your home and remove hot air, a fan on the evaporator blows air inside the house across the evaporator fins. The return grille and ductwork take the hot air through the ducts and into the evaporator. The hot air is actually used to expand the gas in the evaporator. As the heat is removed from the air, the air and coil are cooled. It is then blown into the house through supply ducts.

This continues over and over until the room reaches the temperature you set your thermostat to. When that happens, the thermostat senses that the temperature has reached the right setting and turns off the air conditioner. As the room warms up, the thermostat turns the air conditioner back on until the room reaches the desired temperature.

This is the basic process by which air conditioners work.

Next time, we’ll talk about how a heat pump cools your home.

Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems).For more information about Indoor Air Quality and other HVAC topics,click here to visit our website