Air Conditioner Troubleshooting Guide

HVAC Logo IconBy Tom MoorJuly 31, 2023
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Home inspector, repairman, adjuster examines air conditioner units at a customer home.  He is using his digital tablet to record results.

Air conditioners are essential to keeping your home cool and comfortable, especially in the summer. When your AC breaks down, waiting for a professional to come to your home and fix it can take days or weeks, depending on scheduling and availability. Often, simply popping open a window or running a fan isn’t enough on a particularly hot summer day. The good news is that there a surprising number of instances in which you can diagnose and repair a broken AC on your own. This article reviews troubleshooting tips and highlights a few common issues and solutions so you can get your AC back up and running.

man checks hvac unit for repair

Troubleshooting tips

  • Make sure the thermostat is set properly. Sometimes fixing your air conditioner is as simple as learning to set the thermostat properly. If set incorrectly, your air conditioner may not work the way you want it to. You might have your thermostat set to heat instead of air conditioning. If this happens, you’ll likely have hot air coming out of your air conditioning vents. It’s easy to forget to make the switch when the seasons change. Double-check this before you assume that your AC unit is broken.
  • Change the thermostat batteries. Have you checked the batteries in your thermostat lately? If you haven’t changed the batteries in a long time, you might be dealing with a dead battery. Without functioning batteries, the thermostat cannot communicate with the air conditioning unit.
  • Replace the air filter. If the filter gets too dirty, the air cannot flow properly. As a result, your air conditioner won’t work as well or maybe at all. Modern air conditioners in particular are extremely sensitive to dirty air filters. If you can’t remember the last time you changed the filters, it’s time to change them.
  • Check your circuit breaker. The next thing you can try is checking your circuit breaker. If the circuit breaker connected to the air conditioner has been tripped, you’ll need to reset it.
  • Check the air vents. Make sure that all of your air ducts and vents are clear. If they get clogged by dust or dirt, the air can’t flow properly; simply cleaning your air vents could be the answer to your problems. There may also be issues within the air ducts that you can’t see. Things like mold or vermin infestation can prevent your AC from working properly.

When to contact an HVAC professional

While there are plenty of things you can do on your own to combat common problems with your air conditioner, there are several instances where you need to contact a professional.

  • Strange Noises Coming From Your AC: Is your air conditioner making loud banging, clanging, or other unfamiliar noises? If these sounds are coming from your air conditioner or vents, you likely have a serious problem. This is not something you can fix on your own, but an HVAC professional will understand the issue and find a solution.
  • Issues with the Outdoor Unit: If your outdoor air conditioner unit is the problem, you should not try to fix this yourself. While changing your air filters and replacing batteries are perfectly fine for you to do on your own, fixing more complicated issues may void your warranty. For true maintenance issues, it’s best to contact a professional.
  • Improperly Installed AC: If you’ve noticed that your air conditioner was not installed properly, you should call a professional to reinstall or fix it.

Frequently asked questions

Why is my AC running but not cooling?
If your AC is running but cold air is not coming out, you should check your filters and air vents. Clogged vents and filters will prevent cool air from flowing.
Why is my house AC not working?
Your best option is to contact a local HVAC professional to pinpoint the issue and resolve it, but there are a few things you can check on your own. Run through the list of AC troubleshooting tips above. If none of those help, it’s time to contact a professional to find out why your AC isn’t working.
What could be wrong with my AC?
Common issues include dirty filters, an unplugged power cord, and clogged vents. If your unit is still not running after working through the AC troubleshooting guide above, contact an HVAC professional for further assistance.
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