5 Reasons Why Your Air Conditioner Stopped Working


The Unit Is Too Small or Has an Old Thermostat

thermostat dial
Old-fashioned dial thermostats are particularly prone to malfunction. Nick M Do/Stockbyte/Getty Images

One big reason for malfunctions is that a lot of home air conditioning systems aren't installed correctly in the first place, says Todd Washam, director of industry and external relations for the Air Conditioning Contractors of America, a trade group that represents about 4,000 contractors across the U.S. and writes standards and manuals for the industry.

Washam says that it's crucial for installers to make careful calculations beforehand on how much cooling a home will need, and to make sure that the air conditioning unit is matched with properly-sized ducts. If the ducts are too small, he says, the unit will have to work harder to cool down the house. That, in turn, increases wear and tear on the components and shortens their lifespan. And if the unit itself is too small for the space, the house will never get cool enough.

Another problem can arise if your thermostat isn't correctly calibrated, particularly common if you have the old-school dial control version. If something is wrong with your thermostat, your air conditioner won't get the necessary instructions on how much to cool your house. Remedy the problem by either having the thermostat recalibrated by a technician, or replacing it with a newer programmable digital unit, which will be more precise and help you to save energy as well. Some of the new devices can even be programmed remotely using your smartphone or tablet, which is a nice convenience.

Author's Note: 5 Reasons Your Air Conditioning Stopped Working

I've never lived in a home with central air conditioning, amazing as that may seem, so working on this article was educational for me.

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More Great Links


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  • U.S. Department of Energy. "Air Conditioning." Energy.gov. (June 10, 2018) http://bit.ly/2JJmEeM
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  • U.S. Energy Information Administration. "Air conditioning and other appliances increase residential electricity use in the summer." Eia.gov. May 22, 2017. (June 10, 2018) http://bit.ly/2sJIIfM
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