Why Would My AC Unit Suddenly Stop Working?

Writen by
Guy's Team
February 12, 2024
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Have you ever been in the middle of a sweltering summer day only to find your AC unit suddenly stop working? Nothing can be more frustrating than a faulty air conditioner when you need it most. A multitude of issues may cause this problem, ranging from simple to complex.

In this post, we'll delve into some common reasons your AC unit might stop working, DIY HVAC troubleshooting tips, and HVAC maintenance suggestions to keep your unit working optimally.

Simple Causes for an AC Unit Suddenly Stopping

Sometimes, the reason your AC unit suddenly stops working may be quite simple and easily rectified. Here are a few common causes:

Circuit Breaker: Your AC unit may stop working if the circuit breaker has tripped. Resetting the circuit breaker might solve the problem.

Thermostat Settings: A wrongly set or faulty thermostat can also cause your AC to stop working. Ensure your thermostat is set to cool and the temperature setting is lower than the current room temperature.

Air Filter: If your AC unit's air filter is dirty, it can lead to insufficient airflow, causing your AC unit to freeze up and stop working. Cleaning or replacing your air filter can often remedy this issue.

Outdoor Unit: Over time, leaves, dirt, and other debris can clog up your outdoor unit, causing your AC to work inefficiently or not at all. Cleaning the outdoor unit regularly can prevent this problem.

Advanced Problems Making Your AC Unit Stop Working

Sometimes, more complex issues could be causing your AC unit to stop working. These are typically harder to fix on your own and may require professional help.

Refrigerant Leaks: If your AC unit is low on refrigerant, it may stop cooling effectively. This issue is usually due to a leak and will need a professional repair.

Compressor Failure: The compressor is the heart of your AC system, and if it fails, your unit will not cool. A compressor failure usually requires a substantial repair or replacement of the unit.

Capacitor Issues: If your capacitor isn't working, your AC's motor may not start. Capacitor issues require professional help to diagnose and fix.

DIY Troubleshooting Tips for a Non-working AC Unit

Before calling a professional, there are a few troubleshooting steps you can try on your own:

Reset your circuit breaker: A simple reset might bring your AC back to life.

Check your thermostat settings: Ensure your thermostat is correctly set to cool and the temperature is set lower than the current room temperature.

Check your air filters: Replace your air filter if it's dirty or clogged.

Inspect the outdoor unit: Clear away any debris that could be blocking airflow.

Professional HVAC Troubleshooting

When DIY solutions aren't enough, it's time to call in the professionals. They can diagnose complex problems like refrigerant leaks, compressor failures, or capacitor issues. Professionals have the necessary expertise and equipment to handle these intricate problems and provide appropriate solutions.

HVAC Maintenance Tips to Prevent Issues

The best way to avoid having your AC unit suddenly stop working is regular maintenance. Here are a few tips:

Schedule Regular HVAC Service: Professionals can identify and fix potential issues before they lead to a complete shutdown.

Change Filters Regularly: Regularly changing your air filter can prevent airflow problems and improve the efficiency of your AC unit.

Keep Your Outdoor Unit Clean: Regularly clean your outdoor unit to prevent debris from impeding airflow.

Inspect Your Thermostat: Regularly check your thermostat's batteries and settings to ensure it's functioning properly.

The Importance of Regular Maintenance

Regular maintenance of your AC unit is crucial for its optimal functioning. It not only helps in avoiding sudden breakdowns but also increases the unit's efficiency and lifespan. It's always beneficial to have a professional take a look at your HVAC system regularly to prevent unexpected failures.


Nobody wants to deal with an AC unit that suddenly stops working, especially in the heat of the summer. Fortunately, with proper understanding, DIY troubleshooting, and regular professional maintenance, these problems can often be prevented.

If you're unsure or facing persistent issues with your AC unit, it's best to call in the experts. At Guy's Plumbing Heating & Air, we have a team of experienced professionals who can help diagnose and fix any problems you may encounter. We also offer maintenance plans to help prevent issues from cropping up and ensure that your AC unit stays in top shape year-round. Don't wait until your AC unit stops working; contact us today to secure your comfort for tomorrow.