What do you know about how your home’s air conditioning system operates? If you’ve ever wanted to know, how does an air conditioner work, we have all the info you need.
Why You Need to Know How Your AC Works
Your home’s central AC needs professional maintenance twice a year to keep it operating at peak efficiency. An HVAC service professional can do this job, but here are some reasons it’s important to know how your air conditioner works:
- If your AC has problems or breaks down, you’ll have enough knowledge to know when you need to call a professional.
- When you’re talking about your AC with an HVAC expert, you’ll be better able to explain problems and to understand what they’re saying.
- Having a little background knowledge can help you make the best choice when it’s time to replace your AC.
Components of an Air Conditioner
Central AC systems have mechanical parts that work to cool air:
- Evaporator
- Condenser
- Furnace or air handler
- Thermostat
They also have a fifth non-mechanical component: refrigerant.
Other parts include the thermostat and circuit board that control the whole system and the air blower and duct network that transports cooled indoor air around the home.
Refrigerant: This circulates inside the evaporator and condenser coils. As the refrigerant moves through the AC unit, it is converted from a liquid into a cold mist and then into a warm vapor before being converted back into a liquid.
Evaporator coil: The function of the evaporator coil is to absorb heat. During the cooling cycle, the evaporator fills up with refrigerant. As it does, heat energy is drawn into the coils. The heat turns the cool refrigerant into a hot gas.
Compressor: The compressor draws in the gaseous refrigerant and compresses it. This makes it denser, hotter, and more pressurized.
Condenser coil: The pressurized refrigerant is forced into the condenser coil. This is similar in structure to the evaporator, but it emits heat rather than absorb it. In a central AC system, the condenser is located outdoors. This lets the system release hot air outside without affecting the indoor temperature. A condenser fan is built into this outdoor unit to help the condenser lose heat.
Expansion valve: When the refrigerant exits the condenser coil, it’s in the form of a hot liquid. To keep the cooling cycle going, it must be converted back into a cold mist. This happens in the expansion valve. As the refrigerant passes through the expansion valve, the pressure drops, which allows the liquid to expand into a mist. The pressure drop also lets the refrigerant expel a large amount of heat, making it cold enough to re-enter the evaporator coil.
Thermostat: Setting the thermostat controls the temperature the system maintains. When the indoor air temperature dips below the thermostat setting, the system turns on. Once that temperature is reached, the thermostat turns the system off.
Control board: This is a circuit board that controls every component in the cooling cycle. The control board ensures each stage of the cycle triggers in the right order at the right time.
Air handler: This pulls warm air from indoors while blowing cooled air into the central duct network.
Duct network: Cooled air is forced into the duct network and into the rooms of the home via vents.
Filter: In addition to cooling air, AC systems also clean it by passing cooled air through a fine filter. Depending on the filter type, it can remove particulates such as dust, pet dander, and pollen. HEPA filters can also remove bacteria, mold, odors, and even some viruses.
Condensate drain pan: As well as cooling and filtering air, central air conditioners remove moisture. When the temperature of air is reduced, a small amount of moisture is released from that air. The moisture condenses around the AC components, and drain pans located beneath the unit collects the water.
How Does an Air Conditioner Work? Step by Step
An air conditioner cools air by converting refrigerant from a liquid to a gas and back again. In doing so, it absorbs heat from indoor air and then transfers that heat to the outdoors.
Here’s how it works:
- The thermostat detects that the indoor air temperature is higher than the set temperature.
- The thermostat triggers the system to turn on.
- The blower pulls in warm air, passing it over the evaporator coils.
- The refrigerant absorbs heat from the air.
- Cold air is forced through the duct network and distributed throughout your home.
- Refrigerant is transferred to the outdoor compressor, where it releases the absorbed heat.
- Refrigerant is returned to the evaporator as it cools.
- The cooling cycle repeats until the indoor air temperature reaches the set point.
- Once the air temperature is right, the thermostat triggers the AC to switch off.
- The temperature slowly increases until it goes over the set point, and then the cycle starts again.
How to Turn Your AC Off for Winter
Unless you use a heat pump, which can provide both heating and cooling, it’s best to turn your AC off during the winter. To do this, locate the breaker switch, and turn it off. The breaker switch is usually located outside on or near the condenser unit. Just lift up the safety cover, and you should see the switch on the underside of the cover.
Once you’ve turned the AC off, this is a good time to do outdoor maintenance. Check for rust, cracks in the casing, or pooling water. Clean off debris or dust, and trim back any plants that are growing too close to the unit.
If you notice any issues, such as rust, cracks, or pooling water, it’s better to get them fixed over winter, if not in the fall. Letting those problems sit over winter only allows time for them to get worse. And if you fix any issues in the fall or winter, your AC will be in good shape for the summer to come.
Other Types of Air Conditioning Units
All these AC options work in the same way as central AC but with some important differences. These differences make them suitable for specific purposes or rooms in the home.
Window AC
A window unit has the same components as central air conditioning, including an evaporator, condenser, and compressor, plus refrigerant. But it’s all installed within a metal unit that’s small enough to place in a window. With this air conditioner, hot air is vented out the window, and an interior fan circulates air that is cooled by the condenser.
Zoned AC
In a zoned AC system, a single AC unit cools the entire house, just like a normal central air conditioning system. But the house is split into zones via electronically controlled dampers installed in the duct network. This allows temperature for each zone to be controlled independently of the others. Zoned AC is especially useful for larger homes and multi-level homes, as these are more likely to need independent temperature control.
Mini Split AC
A mini split is a kind of heat pump, meaning it can provide both heating and cooling. But mini splits aren’t connected to a duct network. In a mini split AC system, each individual unit is installed in a separate room or zone and controls temperature for that room independent of the others.
Mini splits are ideal for older homes that don’t have room for central AC ductwork. They’re also a useful addition in converted garages, attics, or outbuildings when it’s expensive or inconvenient to extend the AC network.
Need Help with Your Central AC? Call CW Service Pros Today!
Whether or not you have zoned AC or mini splits, air conditioning systems are complicated. Even when you know how they work, there are maintenance and repair jobs for which you need an expert. CW Service Pros can help keep your AC in good shape, so you can stay cool all summer long.
