Air Conditioning

Is It Possible to Have a Too Cold AC?

David Rampey ·

too cold ac

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A too cold AC might seem like a blessing on one of our hot Oklahoma summer days. However, things aren't always what they seem. Setting the home’s thermostat excessively low isn’t good for your air conditioner or your monthly energy budget.

The 78-Degree Sweet Spot

According to research by the Environmental Protection Agency, 78 degrees is the optimum thermostat setting at which a typical AC cools most effectively and economically. A residential air conditioner’s capacity to cool the indoor environment is generally limited to 20 degrees below the outdoor temperature. For example, if it’s 95 degrees outside, you shouldn’t expect the AC to maintain inside temperatures below 75 degrees no matter how low you set the thermostat. Attempting to maintain a too cold AC thermostat setting can impose excess stress on HVAC components and may eventually cause expensive damage too.

Here are some examples of what may happen when homeowners expect too much cool on too-hot days via a too cold AC:

  • Cooling costs rise sharply. For every degree you lower the thermostat setting below the 78-degree standard, energy consumption climbs, causing the air conditioner’s contribution to the monthly electricity bill to increase by 1% to 3%.

  • Longer cycles cause more wear and tear. An excessively low thermostat setting will cause the air conditioner to run longer and longer cooling cycles, perhaps eventually running nonstop. This overheats the AC compressor, which may lead to an automatic system shutdown — not a welcome event on a hot summer day. Permanent damage to the compressor, which is typically the most costly component in the system, may also occur.

  • Evaporator icing. A too-cold thermostat setting may cause layers of ice formation on the air conditioner’s indoor evaporator coil, eventually totally blocking airflow through the coil. This can be another potential cause of a system shutdown, as well as permanent damage to the compressor.

Talk to the experts at Air Assurance for more information about the drawbacks of a too cold AC in hot summer weather.