How Long Does It Take an AC System to Lower Temperatures?

South End Plumbing, Heating, & Air Expert Tips

How Long Does It Take an AC System to Lower Temperatures

Your house is way too hot. It could be you had the AC off for a long stretch. It could be a failing system. A hot house can be very uncomfortable, and cause even more problematic issues. If you’re turning the AC on again and trying to cool a whole house, how long should it take the AC to lower temperatures?

The average air conditioning unit in a house, in an average-sized property, takes about three hours of running to cool a house 10 degrees. This average may vary on factors such as the outdoor temperature, humidity, levels of the house, the AC and HVAC’s efficiency and more. So take an example of going from 82 degrees to 72 for a whole house, it should take about three hours.

Why Does It Take This Long?

It can be very uncomfortable, annoying, stressful, even unhealthy, if your home air conditioning has been out. Perhaps there’s been a power outage during a Carolinas summer. Maybe you were out of town, the AC was off for days, and now your home is 10-15 degrees warmer than normal.

First, a little good news, just because you have this situation, it doesn’t mean your AC or HVAC is broken. You don’t need to skip straight to total replacement and major expenses. Your house will probably take a few hours to get back to a cool, normal temperature and that’s how your system has to work. It’s likely this is happening in a hot time of year. This means the AC is working to cool a warmer indoor climate and working against the typical summer heat and humidity in our Charlotte area.

Most of the time, in this circumstance your air conditioning system is operating perfectly fine. Still, when it’s hot outside and hot in your house, you’ll try anything to make it better.

What Factors are Important?

There are a number of variables that impact how long it takes for your air conditioning to cool off your home. Right here are some of the definite factors.

  • Filters – The air filters need to be changed regularly. They become dirty and clogged as they do what they’re supposed to do. If it’s been months since you checked and changed them, this buildup of dirt will obstruct airflow and make your AC have to work a lot harder to cool your house.
  • The age and maintenance of the AC – If you’ve had your air conditioner system for over 20 years, it’s time for a replacement. Not only will a newer device cool your house down quicker, it will cool it and use energy more effectively as a result of current environmental guidelines.
  • Insulation – If your house does not have appropriate insulation, your air conditioner will not function at the right efficiency. Insulation’s purpose is to decrease heat transfer when it’s warm outdoors and decrease heat loss in the winter.
  • Time of year – In general, the hotter it is outdoors, the longer it’ll take your home to cool down. While proper insulation and other more temporary steps such as closing drapes around the house help, AC will generally need to run more and harder when it’s hot and humid.
  • The size of the house – The larger the house, the slower it’ll cool everywhere in the house. For an average, for a 3 or 4 bedroom home, it should take about three hours to make a 10 degree difference with air conditioning.

What Else Can I Do?

How can you help cool your home faster? Many of these ideas also help the AC run less, so you save some on the energy bill. If your AC is in good working order, you can help keep your home feel cooler.

  1. Close drapes and curtains – Close all curtains and shutters to decrease the sunlight and ambient heat entering the house.
  2. Stay up to date with filters – If you know you’re behind on checking and changing the air filters around your house, this lets your AC be more efficient and prevents major wear or damage in the long run.
  3. Use ceiling fans – If you have ceiling fans in your home, use them to help circulate air.
  4. Check the thermostat – Make sure the fan on your unit is set to “on.”
  5. Use more fans – Get a few electric or battery-powered fans and turn them on full speed. Good airflow doesn’t actually change the temperature, but you feel cooler.
  6. Hold off with appliances – Avoid using devices that can produce more heat, like ranges and washing machines, while you are awaiting your home to cool.
  7. Keep lights off – You can keep lights off or dimmed. If you have LED lights, these don’t produce or give off heat.

What if the Weather Outside isn’t to Blame?

Sometimes, the temperature or weather outside isn’t a factor for your AC struggles. If your home is too hot, but it’s not in the 80s or 90s outside, you have another issue.

It could be the cooling agent or refrigerant in your AC system is low, leaking or failing. There could be another problem with a component. Refrigerant is supposed to effectively capture and remove heat from the air flowing through the HVAC. If there’s a refrigerant or mechanical problem, you need to contact an expert technician to service your system.

Another potential factor is the size of the HVAC or AC compared to the size of the home or building. You could have a system which isn’t compatible for your home. An expert pro can check this and guide you through the next steps. Trying to figure this equation takes a lot of factors into consideration. Windows, insulation, square footage, floors, the age of the home are some of what goes into an efficient match.


At South End Heating and Air we are Charlotte’s affordable AC experts. Call us anytime for a free consult and free estimate. We’ll evaluate your system and help make recommendations for optimum value. After all, we want to keep you cool all summer long and warm in the winter. Just schedule a visit with one of our technicians to talk about how we can help. Would you like to learn more options our techs can help you with? Give us a call 704-684-5339.

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