“My air conditioning runs and runs. My power bill is going to be sky high!”


We have heard this statement from several customers and want to shed some light on why your AC may be stuck running constantly. Luckily, there are more concrete reasons as to why your AC won’t stop running than Forrest Gump’s answer: “I just felt like running.” First of all, you need to determine whether your unit is running and cooling or running and not cooling.

Is your AC running constantly but house not cooling enough?

If your air conditioner is running but not able to cool your home properly, there are a number of possible causes. Here are a few common reasons that you could check before calling your HVAC tech:

  • Dirty air filter

You should be changing your air filter every month to every 3 months, depending on the filter type. Dirt and hair build up in your filter and block the flow of cool air into your home.

  • Dirty outdoor coils

Part of Stiles’s routine maintenance check is cleaning the outdoor coils on your AC unit–and it’s for a good reason! Dirty build up on the coils makes the unit a lot less efficient and can even cause damage over time. Cleaning coils is not something that you should do on your own but you should schedule regular maintenance and your HVAC tech will take care of this for you.

  • Frozen indoor coils

If your indoor unit has ice on the coils, it’s a sure sign that it is not cooling like it should (even though the coils are frozen…ironic!). The best thing you can do after making sure your air filter is clean and outdoor unit is free of debris is to turn off the unit and let it unthaw, then try starting it again.

  • Thermostat setting/programming issues

Even though it seems too simple to be true…you may just have a thermostat setting issue. We have had several customers think that their AC wasn’t cooling properly when actually they didn’t realize that they or a family member had unknowingly changed the set temperature. This is especially true for a programmable thermostat: double check that when you think the house should be 75° that the program is actually set for 75°. If you have recently had a power outage and your thermostat has no battery back-up, the program will go back to its default setting and you will need to re-program it.

  • Doors open or improper insulation

If your air conditioner is struggling and not cooling your home completely during a heat wave it may be due to poor insulation in your home. Check to be sure all windows are closed and if possible close all curtains to block out heat from the sun. Also check with your family members to make sure no one else is leaving doors or windows open and letting out cool air. You might be surprised how often one of our techs arrives at a home that the homeowner said wasn’t cooling well to find a front door open!


Is your AC not turning off when it does reach the correct temperature?

If your AC does reach the temperature you want it to but still doesn’t stop running, there is probably something going wrong with your thermostat:

  • Your thermostat is set to “On” instead of “Auto”

Setting your thermostat to “On” means that the fan will run all the time even when the unit is not cooling. This isn’t good for a variety of reasons (like putting humidity back in your home) but definitely uses energy to keep the fan running when you don’t have to.

  • Your thermostat isn’t calibrated correctly

Thermostats need to be calibrated from time to time to be sure that they are indeed registering an accurate temperature. Ask your HVAC tech if you think your thermostat needs to be re-calibrated.

As always, give Stiles a call if you find that none of these solutions work for you. You may have a much larger problem on your hands than some of the simpler causes outlined above.