Many homeowners assume that running their air conditioning system will replace the stagnant indoor air in their homes with fresh air from outside of their homes. After all, air conditioning systems have an outdoor unit. While conventional wisdom may lead you to believe that this outdoor unit brings in fresh air from outside of your home, this isn’t the case. For a better understanding of air conditioning systems and why they don’t bring in outside air, keep reading.

AC Systems Recycle Indoor Air

Air conditioning systems don’t bring in outside air. Instead, they recycle indoor air.  

When running your air conditioning system, the indoor air will circulate throughout your home. It will enter the return vents where it travels to the evaporator coil. The evaporator coil will absorb the heat of the indoor air. The newly cooled indoor air will then enter the ductwork before being distributed throughout your home’s living spaces. This cycle will continue to repeat until your air conditioning system turns off.

Why AC Systems Don’t Bring in Outside Air

Why don’t air conditioning systems bring in outside air exactly? It’s simply not how they are designed to work. Your air conditioning system would struggle to cool your home if it brought in outside air. During the summer, of course, the air outside of your home will probably be warmer than your home’s indoor air. Your air conditioning system would have to work overtime to cool this outside air.

Another reason air conditioning systems don’t bring in outside air is to minimize airborne pollutants. There are airborne pollutants everywhere, including the outdoors. Air conditioning systems are equipped with a filter to remove these pollutants. As your air conditioning system circulates your home’s indoor air, it will remove pollutants via the air filter.

If your air conditioning system brought it outside air, it wouldn’t be able to effectively remove airborne pollutants. It would actually introduce new airborne pollutants into your home. The air outside of your home contains pollutants. By pumping this outdoor air into your home, your air conditioning system would raise levels of indoor air pollution.

In Conclusion

Central air conditioning systems recycle indoor air rather than bring in outdoor air. This is because they are designed to remove heat from the indoor air. Air conditioning systems work by removing heat from the indoor air. Using refrigerant, they carry this heat from the evaporator coil to the condenser coil. At the same time, recycling indoor air allows air conditioning systems to better control indoor air pollution.