Is My AC Running Too Long?

Keeping cool doesn’t have to make your wallet sweat.


Summer is for poolside adventures, family BBQs, and walking that fine line between “getting a little color” and “Where’s the aloe?!” New bathing suits, summer camps, and feeding all the neighborhood kids can get really expensive. And it’s not exactly cheap to keep your home cool when temperatures rise.

Many people just accept significantly higher utility bills in the summer as normal. To a certain degree (pun intended), that’s true. But sometimes, those bills are unnecessarily high. If you notice your AC is running longer than normal—or worse, running constantly—it’s time to investigate.

How long do air conditioners normally run?

It’s hot outside. With rising temperatures, it’s normal for your AC to run longer. It’s actually a good thing! A longer-running air conditioner decreases wear-and-tear and dehumidifies your home. But it obviously  should turn off at some point.

More specifically, your AC should cycle (turn on) about every 15 minutes on a normal summer day. If it’s more of an I’m-going-to-melt-if-I-go-outside day, your AC may run in longer cycles—like 30 minutes. But if it’s more than that, especially if you don’t notice a significant difference been the inside and outside temps, don’t ignore it! You’re likely wasting energy, putting stress on your system, and heading toward steep repair bills.

Don’t let cooling your home become unnecessarily expensive this summer. Use these six simple questions to find out if your AC is running too long (and what you can do about it).

Question 1: How cool am I trying to get?

If you’re trying to cool your home to 65 degrees on a 100-degree day, your AC’s likely going to run constantly. That doesn’t mean there’s something wrong with your unit; it means your expectations are a bit unrealistic. Raise your thermostat to a more reasonable temperature so you can stay out of the heat and save money on utility bills and future HVAC repairs. 

Question 2: Are my bills similar to last year’s?

If your utility bill this year is comparable to last year’s, your AC’s probably OK. But if you’re seeing a spike in your bills, it’s important to find the cause. Higher bills usually means your AC is working much harder to maintain your desired temperature. This could be caused by:

  • A leak
  • Ineffective or old seals around doors and windows
  • An AC unit that needs maintenance or replacement

Question 3: How’s the airflow?

If the airflow is cool and normal but your AC doesn’t get you to the desired temperature, your unit might not be big enough for the job (literally). Have one of our technicians come out and do a heat load calculation to determine the exact size unit you need for your home. 

If the airflow is cool but weak, check for:

  • Dirty air filters
  • Closed or blocked vents
  • Damaged ductwork
  • Frozen evaporator coils (More on this later.)

The first fix is to change out dirty filters. Highly restrictive filters (like those for pollen or pet hair) can be tempting, but the more restrictive the filter, the less airflow you get on those hot summer days. Try a less restrictive filter first and see how your AC performs.

Next, open air vents in every room. Yes, even the storage room that nobody is ever, ever allowed to see. This helps the airflow circulate around your home and leads to better AC performance.

If the airflow is not cool, check for a leak or a frozen evaporator coil. Other signs of a leak or frozen coil include ice build-up or bubbling/hissing noises from your AC. You may also have low refrigerant, which needs to be replaced by an AC contractor or HVAC technician ASAP. 

Question 4: How’re my coils?

If your AC seems to be working overtime, the coils themselves may need attention. There are two kinds of coils. Evaporator coils, found on the part of your AC system inside, absorb heat from the air. Condenser coils, part of the outdoor AC unit, disperse that heat. If either set of coils is blocked by dirt or ice, hot air can’t escape from your home. 

There might be something wrong with your coils if:

  • Your airflow isn’t cool
  • You see dirt or ice on the coils
  • Your AC is bubbling or hissing

You can clean the outside parts of the unit yourself, but the inner coils are more difficult (and too risky) to reach without the help of a trained technician.

Question 5: How old is my AC unit?

If your AC was recently replaced, it may be too small or too big for your home. If it’s too small, your AC will have to run constantly to reach your desired temperature. If it’s too big, the AC won’t run long enough to pull the humidity out of the air. Your home will either be too hot for comfort, damp and sticky, or both. 

If your AC has never been replaced or routine maintenance has slipped further down the to-do list, it may be time to replace the unit. An old unit will have to work harder to keep you cool (which may be why it’s running so long).

Our qualified technicians can help you determine your next steps so your family and your wallet don’t have to sweat.

Question 6: Is it my thermostat?

Maybe the air conditioner itself isn’t the problem! If your thermostat isn’t registering the correct temperature, your AC will continue to run. Try placing a thermometer near the unit for about an hour. If the thermometer matches the temperature reported on the thermostat, you’re in good shape. If the temps don’t match, you probably need to replace the thermostat.

Bonus Question: When is it time to call a technician?

AC is no joke, especially when it’s in the triple digits. Quick fixes like adjusting your thermostat, opening your air vents, and replacing air filters are DIY solutions to your AC problems. After that, give us a call for your Columbia HVAC questions and maintenance. We can help you keep your cool!

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