Advanced Air

How Long Should it Take a Central AC to Cool My House?

July 13, 2016

Florida summers are no joke.

So if your AC takes longer than it should to cool your house off, you’re probably desperate for some quick answers.

But without knowing more about your home, your AC unit and the outdoor temperature, it’s tough for us to give you an accurate answer to this question.

While there is no one-size-fits-all answer, we can tell you that if your air conditioner runs all day without reaching your set temperature, you might have a problem.

Let’s take a closer look at 5 things that slow down the time it takes your central AC to cool your home.

1. The outdoor temperature

If your AC struggles to reach the set temperature on very hot days, it doesn’t necessarily mean there’s something “wrong” with your air conditioner.

Your air conditioner is designed to keep up with what’s called “design temperatures”. Design temperatures are the range of outdoor temperatures that a city stays between for 99% of the year.

For example, Florida’s design temperatures are between 47 and 93 degrees. So over 99% of the year, we never see temperatures over 93 degrees Fahrenheit.

But when we do, your AC will struggle to keep your home cool.

What to do: There’s not much you can do but the good news is that this won’t happen often (1% of the time, remember?). Try closing all the curtains to keep the heat out.

2. A dirty air filter

Clean filter (left) vs. a dirty filter (right).

If your air filter is clogged, it restricts the amount of air it pulls into the AC system.

Imagine how hard it would be to breathe with a heavy blanket over your mouth. Not easy, right? Over time, it’s not good for your body.

It’s not good for your AC system either. Less airflow puts strain on your unit and slows down your AC’s ability to cool your home. Check out our article “Forgot to Change Your AC’s Filter? 3 Reasons You’ll Regret It” to learn more about how dirty air filters can do damage.

What to do: Check your air filter regularly. When it looks like the filter on the right in the picture above, replace it immediately.

3. Leaks in your air ducts

If there are holes in your air ducts or if they were improperly connected, a good amount of cool, conditioned air escapes into unconditioned areas (basement, spaces behind walls, etc.).

In fact, Energy Star estimates that about 20-30% of your conditioned air is wasted by leaky ducts.

What to do: Have a professional inspect your ductwork. They’ll be able to identify leaky areas and repair them.

4. Low refrigerant levels

Refrigerant is an important part of your AC system. It’s the cooling agent that moves heat from inside your home to the outdoor air.

When your AC is low on refrigerant, it can’t remove heat from your home as quickly.

But if a professional tells you that you are “low on refrigerant” it means you have a refrigerant leak.

What to do: Only a professional that is certified to handle refrigerant should inspect your unit. Make sure that they find and repair the leak BEFORE they recharge your system with more refrigerant.

5. An AC that is too small

Air conditioners are like shoes: They must be sized properly or there will be issues.

For example, if your air conditioner is too small for your home, it will run constantly but cool your home poorly.

Determining the right size AC for your house should be left to a professional, not to “rule of thumbs” like the square footage of your home.

A professional contractor will perform a Manual J Load Calculation; this calculation takes into account a whole list of factors like:

  • The size of your home
  • Geographical area
  • Insulation
  • Windows
  • And much more

If your contractor didn’t perform this calculation and your AC runs constantly but doesn’t cool off your home, you may have an undersized AC unit.

What to do: Have a professional perform a Manual J Load Calculation to determine the right size AC for your home. Then replace your current system with a properly sized AC unit.
” for a good start on finding the right AC size.

Need a Florida HVAC professional?

If you’re not sure what is causing your AC to struggle, schedule an appointment with Advanced Air today.

Our professionals will inspect your house and unit to find and fix your issue.


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